Burn assessment is the first skill a first aider needs before treating a burn, because the right response depends on two things: how much of the body is affected and how deep the damage goes. A small, shallow burn can be managed at home, while a larger or deeper burn can cause life-threatening fluid loss, shock and infection. This guide explains the rule of nines, how to judge burn depth and which burns always need urgent medical care.
Why Burn Assessment Matters
When skin is burned, its protective layer is destroyed and tissue fluid leaks out of the damaged area. The larger the area, the greater the fluid loss, and the higher the risk of shock and later infection. Children and older adults are especially vulnerable. Careful burn assessment helps you decide whether to cool and dress the burn, or to call an ambulance immediately. For treatment steps see our guide to burns first aid for flame burns and scalds.
Burn Assessment of Area: The Rule of Nines
The rule of nines divides an adult body into areas of about nine per cent each, so you can estimate the total burned area quickly.
- Head and neck: 9%
- Each arm: 9%
- Front of chest: 9% and back of chest: 9%
- Abdomen: 9% and lower back: 9%
- Front of each leg: 9% and back of each leg: 9%
- Genitals: about 1%
In children the head is proportionally larger and the legs smaller, so the adult figures overestimate leg burns and underestimate head burns. A quick bedside alternative is the palm method: the flat palm of the injured person, including the fingers, is roughly one per cent of their body surface.
Burn Assessment of Depth
| Depth | What you see | Pain |
|---|---|---|
| Superficial (outer layer) | Red, swollen, may be blistered | Painful |
| Partial thickness | Moist, blistered, red or mottled | Very painful |
| Deep or full thickness | Pale, waxy, leathery or charred, with a red border | Little or no pain in the centre because nerves are destroyed |
Be careful with pale areas. They often indicate a full-thickness burn, and a burn that looks painless is not necessarily minor. All deep burns need medical treatment regardless of size.
Serious Burns That Need Urgent Medical Care
Any of the following should be treated as serious after burn assessment, and the ambulance should be called:
- Any deep burn, particularly in infants and children
- A superficial burn covering about 9% of an adult or 5% of a child (a patch larger than the person’s hand)
- Burns to the hands, feet, face, armpits, genitals, joints or airway
- Any suspected inhalation burn, such as soot around the nose or a hoarse voice. See inhalation burns first aid
- Chemical or electrical burns, which often cause deeper damage than they appear. See chemical burns first aid and electric shock first aid
- Burns in babies, small children, older adults or people with other medical conditions
Common Mistakes in Burn Assessment
- Judging depth only by pain, when deep burns can be painless.
- Forgetting to count burns on the back or other hidden areas.
- Including areas of simple redness, which may not be burned tissue, in the total.
- Delaying cooling while measuring. Start cooling first, then assess.
- Waiting to see how a burn develops. Burns can deepen over the first 48 hours, so re-check them.
Recording Your Burn Assessment
Note the cause (flame, scald, chemical, electrical), the time of injury, the estimated area and depth, the parts of the body involved and any first aid given. Handing this information to paramedics saves time. Combine it with a general check of breathing, pulse and alertness, as described in our vital signs observations guide, and treat any signs of shock.
Frequently Asked Questions
What is the rule of nines?
It is a method of estimating the percentage of body surface burned by dividing an adult body into areas of nine per cent, and it is used to judge the seriousness of a burn.
Is a painless burn less serious?
No. A painless, pale or leathery burn may be full thickness, which is more serious than a painful superficial burn.
Do all burns need a medical review?
Not all. Small superficial burns can be treated at home, but anything deep, large, in a sensitive area or in a child should be assessed.
References and Further Reading
Last updated: November 2026
Prepared by: EHS Guidelines Editorial Team
This article is general educational information and is not a substitute for accredited first aid training or professional medical care. In an emergency, call your local emergency number immediately. Emergency numbers, medicines and protocols differ between countries, so follow local guidance.
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