Burns TBSA and Parkland Formula Calculator — Lund and Browder

Burn depth is conventionally described in four bands: superficial (epidermal), red and dry and painful and blanching, healing in days without scarring; superficial partial thickness, blistered, moist, pink, very painful, brisk capillary refill; deep partial thickness, blotchy red or pale, less painful, sluggish or absent refill; and full thickness, dry, leathery, white or charred, insensate, no refill.

Only the partial and full thickness burn goes into TBSA. Simple erythema does not — which is why the tool carries that warning across the top of the drawing area, and why it is the first thing to check when a percentage looks surprising.

Blanching is the most useful bedside sign

Press, release, and watch. Brisk refill means the dermal circulation is intact. Absent refill in a non‑blanching wound means it is deep, and the UK referral guidance uses exactly that language: “All burns that are not blanching should be referred to a specialised burn service” NNBC.

Depth declares itself late

Burns evolve. A wound that looks superficial partial thickness at two hours may be deep partial thickness at 48 hours, through progression of the zone of stasis. Two practical consequences: an early assessment is provisional and should be recorded as such, and a burn that has not healed within two weeks needs referral regardless of how it looked on day one NNBC.

Three methods are in common use, and they are not interchangeable.

Lund & Browder chart

The reference standard, published in 1944, and what this tool implements. Its value is that it grades the head, thighs and lower legs by age. In a newborn the head is around 19% of surface area and each thigh around 5.5%; by adulthood the head is about 7% and each thigh about 9.5%. No other bedside method captures that.

Wallace rule of nines

Fast, memorable, and built for adults: 9% per arm, 18% per leg, 18% anterior trunk, 18% posterior trunk, 9% head, 1% perineum. It is a reasonable field approximation in an adult of average build. It is wrong in children, because it gives the head 9% when in infancy it is closer to 19%. When a 3D‑scanning study compared the rule of nines against measured surface area, agreement was poor across most body regions — and, interestingly, the trunk figures fitted better as BMI rose, not worse COHORT [Evidence 6].

The palm

Useful for small or scattered burns. The common teaching “the patient’s palm is 1%” conflates two different things. Measured directly, the whole hand including the fingers is close to 1% (0.92% in adults, 1.06% in children); the palm alone is about half that (0.50% and 0.63%) COHORT [Evidence 5]. If you count palms and call each one 1%, you will roughly double a patchy burn.

Front and back are not interchangeable

On this tool the anterior figure faces you, so screen‑left is the patient’s right. The posterior figure faces away, so screen‑left is the patient’s left. Both figures carry an R and an L marker for that reason. It matters for documentation and for the operative plan, even though it never changes the total.

Cool running water for 20 minutes, ideally immediately but of benefit up to three hours after injury, is the standard recommendation internationally. It is worth knowing how good the evidence actually is, because it is better than most people assume and it is still worth starting in the emergency department if it was not done at the scene.

Those figures are from a Queensland cohort of 2,495 children, where adequate first aid meant 20 minutes of cool running water COHORT [Evidence 1]. A bi‑national adult and paediatric registry study found a dose‑response relationship with duration, and reductions in graft probability, ICU admission and length of stay [Evidence 2]. Both are observational, so residual confounding is real — but the direction, the consistency and the dose‑response are persuasive, and the intervention is a tap.

Cool the burn, warm the patient

The two are not in conflict and both are your job. Hypothermia is a genuine hazard in a large burn or a small child: the wound has lost its barrier, the patient is wet, and the resuscitation room is cold. Cool the burned area with running water; cover everything else; warm the room; warm the fluids. Do not use ice or iced water — it causes vasoconstriction and can deepen the injury.

Then cover it

Cling film is the standard interim dressing: it is clean, non‑adherent, transparent for reassessment and does not need removing before the burn service sees it. Lay it in sheets along the limb rather than wrapping circumferentially, so that it cannot constrict as oedema develops. Do not apply it to the face, and do not use it over chemical burns before irrigation is complete.

The tool applies 4 mL × kg × %TBSA of Hartmann’s over 24 hours in adults, and 3 mL × kg × %TBSA plus separate maintenance in children, with half in the first eight hours from the time of the burn and half over the following 16. Thresholds for starting intravenous resuscitation at all are ≥15% TBSA in adults and ≥10% in children, where “child” means under 16 years — the definition used by the UK referral guidance, and the one the tool applies. A 15‑year‑old gets the paediatric multiplier, the paediatric threshold, maintenance fluid and the paediatric urine‑output target.

Which multiplier?

You will see 2, 3 and 4 mL/kg/%TBSA in different sources and they are not errors. The original Parkland formula was 4 mL/kg/%TBSA of lactated Ringer’s, and — a detail usually forgotten — it also included a plasma infusion of 0.3–0.5 mL/kg/%TBSA that modern versions dropped [Evidence 7]. ATLS 10th edition starts adults with thermal burns lower, at 2 mL/kg/%TBSA, reserving 3 mL/kg for children and 4 mL/kg for electrical injury, precisely because of concern about over‑resuscitation ATLS.

There is no UK national standard for the adult multiplier, and it is worth knowing that rather than assuming one exists. The 2022–23 National Burns Audit covered every adult burns critical care admission of ≥15% TBSA across 14 centres and units in England, Wales and Northern Ireland, and one of the variables it had to collect from each service was which multiplier that service used — 2, 3 or 4. The median volume actually delivered in the first 24 hours was 3.43 mL/kg/%TBSA (IQR 2.50–4.49), with about a third of patients receiving more than 4, and the authors report “significant variability in resuscitation practices across the United Kingdom” [Evidence 9]. At the low end, North Bristol’s burn ICU protocol uses a modified Parkland of 1.5 mL/kg/%TBSA.

So the tool offers 2, 3 or 4 as a selectable adult multiplier, defaulting to 4, because Parkland is what UK emergency departments are taught and starting higher then titrating down is the more forgiving direction in a department that will hand the patient over within hours. But the number that matters is the receiving unit’s, so ask, and change it. Children are unaffected: 3 mL plus maintenance is the figure in ATLS, in the UK burn network guidance and in this tool. What every source agrees on is the next sentence.

Fluid creep

The error runs both ways, and ATLS names both: under‑resuscitation gives hypoperfusion and end‑organ injury; over‑resuscitation gives increased oedema, which drives burn depth progression and abdominal or extremity compartment syndrome ATLS. In children there is a second squeeze — a higher volume requirement per unit body mass because of the larger surface area, against a smaller intravascular volume that makes overload easier to cause.

Through the 1990s and 2000s burn units consistently gave more fluid than the formula predicted, a phenomenon named “fluid creep”. The excess appeared largely as progressive oedema in unburned tissue, accumulating after the first eight hours, and was linked with abdominal compartment syndrome and other complications [Evidence 7]. The lesson for the emergency department is narrow but important: the risk runs in both directions, and the early hours — where we work — are where over‑resuscitation is seeded.

Children need maintenance as well

Resuscitation fluid replaces losses; it is not maintenance. A child also needs ordinary maintenance fluid containing glucose, running throughout, calculated by the Holliday‑Segar rule (100 mL/kg for the first 10 kg, 50 mL/kg for the next 10, 20 mL/kg thereafter). The tool runs this as a separate constant‑rate line and uses an isotonic solution with glucose, consistent with NICE NG29 on intravenous fluids in children. Adults do not get a separate maintenance line.

Since the reason for the glucose is a limited glycogen reserve, the corollary is obvious and still gets missed: measure a blood glucose in any child with a significant burn, and measure it again. Holliday‑Segar also over‑delivers in large adolescents — many units cap maintenance at around 2 litres a day — so treat the tool’s maintenance figure in a 60 kg fifteen‑year‑old as a starting point to be checked rather than a prescription.

Colloid and albumin

Albumin in burn shock resuscitation remains genuinely contested. A meta‑analysis of eight controlled studies and 688 adults found no significant overall mortality effect; a reduction appeared (pooled OR 0.34, 95% CI 0.19–0.58) only after two studies judged to be at high risk of bias were excluded [Evidence 8]. That is a post‑hoc exclusion and should be read as hypothesis‑generating. This is a burn‑service decision, typically from around 12 hours and usually when urine output is not responding — not an emergency department one.

Arriving late

If more than eight hours have passed since the burn, the first‑half window has closed and there is no eight‑hour rate left to quote. The tool stops showing one. Instead it takes everything still outstanding from the 24‑hour total, subtracts what has already been given, and spreads the remainder evenly over the hours left to the 24‑hour mark as a single catch‑up rate. That is deliberately not a bolus. The deficit is made up across the rest of day one and titrated to urine output — pushing it in quickly is how a late presenter ends up over‑resuscitated on top of being under‑resuscitated. Past 24 hours the tool stops offering a rate at all, because the formula no longer describes what this patient needs.

Day two

Requirements fall. The tool estimates 50–75% of the day‑one resuscitation volume plus maintenance, which is a planning figure for the receiving unit rather than something you will prescribe.

Airway compromise in burns is progressive and its timing is unforgiving. Oedema develops over hours, accelerated by the fluid you are giving, and an airway that was manageable at presentation can become extremely difficult later. The decision is therefore anticipatory rather than reactive, and it belongs with your most experienced airway operator.

Features that raise concern include fire in an enclosed space, loss of consciousness at the scene, burns to the face or neck, soot in the mouth or nose, carbonaceous sputum, hoarseness, stridor, or a circumferential neck burn. The UK referral guidance sets out its own minimum definition for inhalation injury: “Visual evidence of suspected upper airway smoke inhalation, laryngoscopic and/or bronchoscopic evidence of tracheal or more distal contamination/injury or unconscious at scene with suspicion of inhalation or raised COHb” NNBC. The same document adds that any concern about inhalation injury with a burn of any size should be discussed with a burn centre.

Carbon monoxide and cyanide

Pulse oximetry cannot distinguish carboxyhaemoglobin from oxyhaemoglobin, so a normal SpO₂ is not reassuring after an enclosed‑space fire. Measure carboxyhaemoglobin on a blood gas and treat with high‑flow oxygen. Remember that a normal COHb some hours after the event, particularly after oxygen has already been given by the crew, does not exclude a significant earlier exposure.

Cyanide toxicity should be considered in an enclosed‑space fire with reduced consciousness, hypotension or a persistently high lactate that does not explain itself. It cannot be excluded at the bedside — there is no test that will come back in time — so the clinical picture is the trigger and empirical treatment is reasonable.

The treatment is hydroxocobalamin (Cyanokit), 5 g intravenously in adults and 70 mg/kg in children, repeated once if the response is inadequate. Two practical consequences worth knowing before you give it: it turns the skin, urine and plasma deep red for up to several days, which is expected and not a reaction; and that colour interferes with co‑oximetry and with a range of laboratory assays, so carboxyhaemoglobin, methaemoglobin, bilirubin, creatinine and several others may read unreliably afterwards. Draw the bloods you want before you give it if the patient’s condition allows. Discuss with TOXBASE or the National Poisons Information Service.

UK referral is governed by the National Burn Care Referral Guidance, published by the National Network for Burn Care in 2012. It stratifies services into burn facilities, burn units and burn centres, and distinguishes “refer” from “discuss”. Throughout this page, and throughout that guidance, “child” means under 16 years — a 15‑year‑old takes the paediatric thresholds, the paediatric fluid formula and the paediatric urine‑output target, whatever they look like.

Its minimum referral thresholds:

The first, second, fourth, eighth and ninth rows are the guidance’s own five‑bullet minimum list, quoted verbatim. The others are requirements stated elsewhere in the same document, collected here so that this table can be used on its own.

And the factors that should prompt a discussion with a consultant in a specialised burn service:

• All burns to hands, feet, face, perineum or genitalia
• Any chemical, electrical or friction burn
• Any cold injury
• Any unwell or febrile child with a burn
• Any concern about co‑morbidities that may affect treatment or healing

Two further instructions from the same page are easy to miss and worth holding on to. If the burn changes in appearance, shows signs of infection, or you are worried about healing, discuss it. And: “If there is any suspicion of Toxic shock syndrome (TSS) then refer early” — relevant because toxic shock in a child with a small burn can present as fever, rash, diarrhoea and shock, and the burn itself may look trivial.

Chemical

Brush dry powder off the skin before you irrigate. Cement, dry lime, elemental sodium and potassium, and phosphorus all react with water — exothermically, and in the case of the alkali metals violently — so reaching for the tap first can add a thermal injury to a chemical one. Remove contaminated clothing, protect yourself and anyone else in the room, brush the powder away dry, and only then irrigate.

Then irrigate copiously and for far longer than feels necessary — the injury continues while the agent is in contact — and irrigate before dressing anything. Alkalis penetrate more deeply than acids and warrant longer irrigation. Never attempt to neutralise a chemical burn: the neutralisation reaction is itself exothermic, so you add heat to a surface that is already injured, and you lose the dilution that irrigation was achieving.

Hydrofluoric acid is the important exception to “just irrigate”: it causes systemic hypocalcaemia and needs calcium gluconate, topically as 2.5% gel and sometimes systemically, with cardiac monitoring and serial calcium. The gel is not stocked everywhere — find out now where yours is, rather than at three in the morning.

For any agent you do not recognise, and for any significant exposure, the UK route is TOXBASE and, if you need to speak to someone, the National Poisons Information Service. All chemical burns warrant discussion with the burn service NNBC. Eye involvement needs its own assessment — evert the lids, irrigate until the pH normalises, and stain with fluorescein; a facial chemical burn with a normal‑looking eye has not had its eye examined.

Electrical

The visible skin wound understates the injury, because current travels through tissue and the damage is deep — ATLS puts it plainly: muscle injury can occur with few outward signs ATLS. Look for an entry and an exit wound, examine for skeletal and muscular damage including spinal fracture from forced muscle contraction, check a creatine kinase, and obtain a 12‑lead ECG.

The TBSA‑based volume is a floor, not a ceiling, in electrical injury. The surface area you can see bears little relation to the mass of muscle that has been cooked, so the formula systematically under‑estimates what this patient needs. ATLS uses the higher 4 mL/kg/%TBSA starting rate here for that reason ATLS, and UK network guidance goes further, allowing up to 9 mL/kg/%TBSA over 24 hours in high‑tension injury NBCN.

The urine target rises with it, and the two sources differ: ATLS says 1–1.5 mL/kg/h until the urine clears, while the Northern Burn Care Network gives 1.5–2 mL/kg/h for high‑tension electrical injury and 2 mL/kg/h where there is frank haemochromogenuria. The tool follows the UK figure and aims 1.5–2, then drops back to the usual 0.5 mL/kg/h once the urine runs clear. Either way the direction is the same and the endpoint is the urine, not the formula.

Myoglobinuria

Do not wait for laboratory confirmation before treating. If the urine is dark red, assume haemochromogens are present and treat on that basis ATLS — the creatine kinase is confirmation, not a decision point. Increase the fluid rate to achieve the higher urine output above. Consult the burn service before starting a bicarbonate infusion or giving mannitol; neither is a first move in the emergency department. And note that electrical injury may need fasciotomy, not merely escharotomy — the damage is beneath the fascia, so releasing the eschar alone will not decompress it.

Monitoring

ATLS reserves prolonged cardiac monitoring for patients with injury from the burn itself, loss of consciousness, exposure to high voltage (>1,000 volts), or cardiac rhythm abnormalities or arrhythmias on early evaluation ATLS. So low voltage is not by itself a discharge criterion — it is the presence of none of those four that permits it, and an ECG has to have been looked at before you can say the fourth is absent.

TEACHING Beyond the ATLS list, many UK departments also monitor after a low‑voltage injury with a likely transthoracic current path (hand‑to‑hand, or hand‑to‑opposite‑foot), wet conditions or immersion, or a tetanic contraction the patient could not let go of. That is convention rather than an ATLS recommendation, and is flagged here as such.

Any electrical burn warrants discussion with the burn service NNBC.

Circumferential burns

A circumferential deep partial‑thickness or full‑thickness burn of a limb can obstruct perfusion as oedema builds beneath inelastic eschar; around the chest it can prevent ventilation. Deep dermal burns do this too — the eschar does not have to be full thickness to be inelastic. Remove rings, watches, bracelets and tight clothing immediately, before the swelling makes it impossible. Reassess perfusion and respiratory mechanics repeatedly rather than once, and document each reassessment so a trend is visible to whoever looks next.

Escharotomy

Escharotomy is usually performed by the burn service, and where transfer is quick that is the right place for it. But it is a time‑critical, limb‑ and life‑saving intervention that cannot always wait for transfer. If a circumferential chest burn is preventing ventilation, or a circumferential limb burn is compromising perfusion, telephone the burn service immediately and be prepared to perform escharotomy locally under their guidance. The decision to defer must be an active one, taken with the burn service and recorded — not a default arrived at by assuming it is somebody else’s job.

So that the conversation is a useful one, know the anatomy before you make the call. Limb incisions run the full length of the burnt segment in the mid‑axial lines, medial and lateral, crossing joints with care. Chest incisions run down the anterior axillary lines bilaterally, joined by a transverse incision across the costal margin, releasing the chest plate. The incision goes through the full depth of the eschar until the underlying fat pouts and the edges separate; it is not a skin‑deep scratch, and it is not a fasciotomy either. Full‑thickness eschar is insensate, but the incision extends into sensate tissue at its margins and beneath, so give analgesia and sedation. Expect bleeding and be ready for it.

All circumferential burns meet the referral threshold outright NNBC.

Safeguarding

Scalds and contact burns are among the commonest presentations of physical abuse in young children. Patterns that should prompt concern include a clear immersion line, a glove‑or‑stocking distribution, sparing of flexures where a child has curled away, symmetrical burns of the buttocks or perineum, and cigarette‑shaped circular burns. So should the non‑anatomical features: a delay in presentation, a history that does not match the burn, a history that changes, or an injury attributed to a sibling. The referral requirement is explicit and time‑bound — within 24 hours to a burn unit or centre for expert assessment NNBC — and it runs alongside, not instead of, your local child protection process.

The same reasoning applies to vulnerable adults and older people, and is easier to miss because the burn is rarely the reason anyone thinks of abuse. ATLS is explicit that intentional burn injury occurs in both children and adults, and that those unable to control their environment — the very young and the very old — are particularly vulnerable to abuse and neglect ATLS. It gives the specific pattern to know: a burn to the posterior aspect of the lower extremities and buttocks in an older patient placed in a bath of hot water. An unexplained immersion‑pattern scald, a contact burn in someone who could not have reached the source, cigarette‑shaped burns, or a delayed presentation in a person dependent on others for care should all trigger your adult safeguarding process. Neglect counts: a burn sustained because supervision or a risk assessment failed in a care setting is a safeguarding matter even when nobody intended harm. Above all, the mechanism and pattern should match the history.

The rest of the ABC

A burn is a distracting injury. In a blast, a fall from a burning building or a road traffic collision, the burn is often not what kills the patient. Analgesia should be intravenous and titrated in anything significant. Check tetanus status. And take the weight properly rather than estimating it, because every fluid number in the tool is multiplied by it — if you genuinely cannot weigh the patient, use a validated estimate and record which method you used, so the receiving unit knows how much confidence the whole calculation deserves.

Before the transfer leaves

Cheap things, easily forgotten, and most of them are harder to do later than now.

• Remove rings, watches, bangles and tight clothing — including from limbs that are not burnt, because oedema is generalised in a large burn. A ring left on through the first twelve hours can cost a finger.
• Check a blood glucose, and recheck it. Small children have limited glycogen reserve and become hypoglycaemic — which is the reason their maintenance fluid contains glucose, and the reason measuring it is not optional.
• Do not give prophylactic antibiotics. They do not prevent burn wound infection, they select resistant organisms in a patient who may need antibiotics that work later, and they are a common reflex. Antibiotics are for a diagnosed infection — or for suspected toxic shock, which is a different matter entirely and is urgent.
• Do not apply silver sulfadiazine (Flamazine) before the burn service has reviewed the wound, in person or by photograph. It obscures depth assessment, which is the assessment the receiving unit most needs to make. Cling film in sheets is the right interim cover.
• Consider an NG tube in a large burn facing a long transfer. Gastric stasis and ileus are usual above roughly 20% TBSA, and a distended stomach in a supine, possibly intubated patient during a two‑hour road journey is an avoidable problem.
• Catheterise anyone being resuscitated, because urine output is the only feedback the fluid plan has.
• Keep the patient warm. Cool the burn, warm the patient — a large burn loses heat fast, and hypothermia worsens coagulopathy and outcome.

1. Case 1 — the number that grew. The blanching skin is superficial burn and does not enter the TBSA. Your mapped figure of about 9% is the one to use: 4 × 70 × 9 = 2,520 mL over 24 hours, not 7,000. At 9% he is below the 15% adult threshold for intravenous resuscitation, so this becomes analgesia, oral fluid, wound care and a referral conversation — 9% is comfortably over the ≥3% adult referral threshold, and his forearms may involve a special area. The right handling of the crew’s 25% is to document your own mapped estimate and the reason for the difference, and to hand over both. It is not a criticism of the crew; pre‑hospital estimates run high in every published cohort.
2. Case 2 — the toddler who was fine. The percentage is the least interesting thing about her. First, referral — and specifically transfer, not a clinic appointment: at 8% and under one year she falls in the paediatric burn‑unit band, which below a year is ≥5–<15% TBSA rather than ≥5–<30% NNBC. She is going to a burn unit today. Second, first aid: “a minute or two” is not 20 minutes, and she is within three hours of the burn, so cooling is still worth starting now — while you actively keep her warm everywhere else. Third, safeguarding — not because anything here is suspicious, but because a scald in an 11‑month‑old requires you to ask whether the mechanism fits the developmental stage and the pattern of the burn, every time. Her 8% is below the 10% threshold for formula‑based resuscitation, which is not the same as a reason to withhold fluid: if she will not drink, is vomiting, or faces a long transfer, cannulate and give fluid on clinical grounds. Check her blood glucose while you are at it. All the things that actually matter here sit outside the calculation.

This is a Lund & Browder burn assessment tool. You shade the burn on age‑appropriate figures, it converts the shaded area into a percentage of total body surface area using the age‑graded Lund & Browder values, and it applies a fluid formula to the weight and percentage you give it.

How the percentage is calculated

Each figure carries a silhouette mask and a set of anatomical regions. For every region the tool counts how many body pixels you have shaded as a fraction of that region’s total, then multiplies by that region’s Lund & Browder percentage. Head, thighs and lower legs are interpolated continuously from the age you type, rather than being taken from a single childhood column. If the age field is empty, a representative age for the selected tab is used.

Left and right

The anterior figure faces you, so screen‑left is the patient’s right. The posterior figure faces away, so screen‑left is the patient’s left. Both figures carry R and L markers.

What the three sections are

The Assessment tool implements Lund & Browder and conventional UK fluid and referral practice. The Teaching and Evidence tabs are different in kind: they are the author’s synthesis, written to explain the tool rather than to extend it. Nothing in them changes what the tool tells you to do. Where they quote UK national guidance the source is named; where they go beyond it, the content is tagged as teaching.

Limitations you should know about

• Shading on a two‑dimensional figure is an approximation of a three‑dimensional surface. It is more reproducible than an eyeball estimate, not more true.
• The fluid figures are a starting point. Titrate to urine output.
• The referral thresholds implement 2012 national guidance. Check your regional burn network for local updates.
• The tool does not assess depth, airway, carbon monoxide, safeguarding or analgesia. Those are clinical judgements it cannot make for you.

Review status

The assessment tool has been clinically reviewed internally. The teaching and evidence content is internally reviewed only and has had no external sign‑off. This is clinical decision support for registered healthcare professionals — always apply independent clinical judgement.