Rule of nines burn calculator
Enter how much of each body region is burned, from 0 to 100 %, to estimate the total body surface area (TBSA) burned with the rule of nines. The child version gives the head a larger share. It is an estimate for information, not a diagnosis.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose adult or child.
- For each region enter the part that is burned: 100 for the whole region, 50 for half of it, 0 if not burned.
- Read the total body surface area burned.
Region shares
| Region |
Adult |
Child |
| Head and neck |
9 % |
18 % |
| Front of trunk |
18 % |
18 % |
| Back of trunk |
18 % |
18 % |
| Each arm |
9 % |
9 % |
| Each leg |
18 % |
14 % |
| Genitals and perineum |
1 % |
— |
TBSA = Σ region share × burned part of the region.
Worked example
An adult with the whole right arm burned and half of the chest and abdomen: 9 × 100 % + 18 × 50 % = 9 + 9 = 18 %.
A child with the same burns plus the whole head: 9 + 9 + 18 = 36 %.
Tips
- Estimates often differ between observers; reassess once the wounds are cleaned.
- The result feeds fluid formulas such as Parkland; the Parkland formula calculator takes the TBSA from here.
- This is an estimate for information, not a diagnosis or a treatment decision. Serious burns need emergency care.
Frequently asked questions
How does the rule of nines work?
The adult body is split into regions worth 9 % or multiples of 9: head and neck 9, each arm 9, front of the trunk 18, back of the trunk 18, each leg 18, and the genital area 1, for 100 % in total.
Why is a child different?
A child's head is much larger relative to the body. The child version gives the head 18 % and each leg 14 %, with the arms and trunk as in adults. In children the more detailed Lund–Browder chart is often preferred; this calculator does not include it.
Which burns should I count?
Count partial-thickness and full-thickness burns. Superficial burns that are only red, like sunburn, are not included in TBSA for fluid calculations.
What about small scattered burns?
For small or patchy burns the palm method is often used: the patient's palm with fingers is about 1 % of their body surface.