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# Burns: estimating the burned area (rule of nines, Lund–Browder) and the fluid formula, with worked examples

- Calculation

The burned area is a percentage of body surface; with the weight it feeds the fluid formula, which is then adjusted to the urine output.

Updated Nov 13, 2026

## Key points

- Educational example, not a clinical order.
- Count only partial- and full-thickness burns; leave out areas of redness only.
- Adults: rule of nines. Children: Lund–Browder chart, because the head is a larger share of the body.
- The 24 hours of the formula start at the time of the burn, not at arrival.
- The formula only sets the starting rate: the infusion is adjusted to the hourly urine output.

## What it is

In a major burn the size of the injury, written as a percentage of the total body surface area (%TBSA), drives the first fluid plan. Adults are estimated with the rule of nines, children with the Lund–Browder chart, and small or scattered burns with the patient's hand. Only partial- and full-thickness burns are counted: areas of simple redness are left out. The fluid formula (for example Parkland) gives a starting volume for the first 24 hours counted from the time of the burn; after that the infusion is adjusted hour by hour to the urine output and other end points. The worked examples cover the burned area and then the starting volume of the formula, on made-up adults.

## Formulas

- Rule of nines (adult): head 9 %, each arm 9 %, front of the trunk 18 %, back of the trunk 18 %, each leg 18 %, genital area 1 %.
- Hand method: the patient's palm with the fingers is about 1 % (it varies with sex and body build); useful for small or scattered burns.
- Lund–Browder chart: gives a different percentage for each body region according to age; it is the most accurate chart, above all in children.
- Parkland formula: volume for the first 24 h = 4 mL × weight (kg) × %TBSA; half in the first 8 h from the time of the burn, the other half over the next 16 h.
- Modified Brooke formula: 3 mL × weight (kg) × %TBSA, split the same way. Current guidance gives a range of 2–4 mL × kg × %TBSA as the starting estimate.
- End point: urine output of about 0.5–1 mL/kg/h in adults; the team sets the exact goal.

## How to calculate it

- Find the time of the burn and the patient's weight — the formula counts from the burn and uses the weight.
- Separate the depths: leave out areas of redness only — they heal in about a week and do not need resuscitation fluid.
- Choose the method: rule of nines in adults, Lund–Browder in children, the hand for small or scattered areas.
- Add the regions burned and write the %TBSA — this number goes into the formula.
- Write the formula with the weight and %TBSA, and let a second person check it — this is a high-risk calculation.
- Subtract the time already passed since the burn and the fluid already given before arrival, as the protocol says — the first 8 h began at the burn.
- Measure urine every hour through an indwelling catheter and record it — the urine output guides every change in the rate.
- Report urine below the goal, rising pulse or falling pressure, and also urine well above the goal or growing oedema — too little and too much fluid both harm.
- Worked example (Parkland, arrives 2 h after the burn, no fluid yet): 80 kg, 27 %: 4 × 80 × 27 = 8640 mL; 4320 ÷ 6 h left = 720 mL/h, then 4320 ÷ 16 = 270 mL/h.
- Worked example (modified Brooke, 3 mL): 64 kg, 25 %: 3 × 64 × 25 = 4800 mL; 2400 mL in the first 8 h = 300 mL/h, then 2400 mL in 16 h = 150 mL/h.

## Worked examples with made-up figures (area, then fluid)

| Case | Data | Calculation | Result |
| --- | --- | --- | --- |
| 1. Adult, scald | Whole front of the trunk and whole right arm, blistered | 18 + 9 | 27 % |
| 2. Adult, flame | Whole head, whole left arm and genital area, deep | 9 + 9 + 1 | 19 % |
| 3. Adult, redness excluded | Whole back of the trunk blistered; front of the trunk red only | 18 + 0 (redness is not counted) | 18 % |
| 4. Adult, scattered burns | Several blistered patches that together cover about 4 of the patient's hands | 4 × about 1 | about 4 % |
| 5. Infant under one year | Whole head burned | Head counts about 18 % at this age (not 9 % as in the adult) | about 18 % |
| 6. Adult, Parkland fluid | 70 kg, 30 %TBSA; counted from the time of the burn | 4 × 70 × 30 = 8400 mL; half = 4200 mL in the first 8 h (4200 ÷ 8 = 525 mL/h); the other 4200 mL over the next 16 h (4200 ÷ 16 = 262.5 mL/h). Check: 525 × 8 + 262.5 × 16 = 4200 + 4200 = 8400 | 8400 mL in 24 h: 525 mL/h for 8 h, then about 263 mL/h for 16 h |

## Common mistakes

- Counting areas of redness as burned: this overestimates the area and the fluid.
- Using the adult rule of nines in a small child.
- Starting the 24 hours at arrival instead of at the time of the burn.
- Keeping the formula rate fixed instead of adjusting it to the urine output.
- Using an estimated weight without saying so in the record.

## Double-checking

- Educational content only, not an order for a real patient. Volumes are set by the treating team per local guidance.
- Ask a second nurse or the physician to repeat the area estimate and the formula independently.
- Check that the time of the burn and the weight in the record are the ones used.
- Compare the hourly urine output with the goal at each hour and record the rate change ordered.
- Say at handover the %TBSA, the hours since the burn, the current rate and the last urine outputs.

## Test yourself

Think of the answer, then tap the question to see it.

## Which burns are counted when estimating the %TBSA?

Only partial- and full-thickness burns. Areas of simple redness are left out because they are superficial and heal in about a week.

## Why is the Lund–Browder chart preferred in children?

Because it changes each region's percentage with age; in young children the head is a larger share of the body and the rule of nines is inaccurate.

## From what moment are the first 8 hours of the Parkland formula counted?

From the time of the burn, not from arrival at the hospital.

## What does the nurse use to adjust the infusion after the formula sets the starting rate?

The hourly urine output through an indwelling catheter, together with heart rate and blood pressure, against the goal set by the team.

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## Connections

## Related 3

- [Nursing the patient with major burns: inhalation injury, circulation to the limbs, wounds, infection, temperature, pain and nutrition](https://durgical.com/en/nursing/nursing-the-patient-with-major-burns-inhalation-injury-circulation-to-the-limbs/)
- [Fluid balance: recording intake and output](https://durgical.com/en/nursing/fluid-balance-recording-intake-and-output/)
- [Indwelling catheter care and removal](https://durgical.com/en/nursing/indwelling-catheter-care-and-removal/)

## Related conditions 1

- [Burns (thermal, chemical, electrical; inhalation injury)](https://durgical.com/en/conditions/burns/)

[← All of nursing](https://durgical.com/en/nursing/)

Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order.

Sources: [Paediatric burn and scald management in a low resource setting: a reference guide and review](https://pmc.ncbi.nlm.nih.gov/articles/PMC6246875/) (African Journal of Emergency Medicine, 2017); [Technical and medical aspects of burn size assessment and documentation](https://pmc.ncbi.nlm.nih.gov/articles/PMC7999209/) (Medicina (Kaunas), 2021); [Effectiveness of Parkland formula in the estimation of resuscitation fluid volume in adult thermal burns](https://pmc.ncbi.nlm.nih.gov/articles/PMC6488519/) (Chinese Journal of Traumatology, 2019); [Burn injury (Primer)](https://pmc.ncbi.nlm.nih.gov/articles/PMC7224101/) (Nature Reviews Disease Primers (Jeschke et al.), 2020).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/nursing/burns-estimating-the-burned-area-and-the-fluid-formula-with-worked-examples/