Body surface area Du Bois calculator
Get body surface area from the Du Bois formula of 1916: 0.007184 times height in cm to the power 0.725 times weight in kg to the power 0.425. A zero or negative value is refused, never guessed. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Height
- 170
- Weight
- 70
- Bsa
- 1.8097078018 m²
- Bsa m2
- 1.8097078018
- Height (cm)
- 170
- Weight (kg)
- 70
Body surface area is a standard estimate of the external area of the human body, used for decades in clinical education, chemotherapy dosing discussions, burn assessment teaching, and physiology labs. The Du Bois formula, published by Du Bois and Du Bois in nineteen sixteen, remains one of the most widely cited power-law models: body surface area in square metres equals zero point zero zero seven one eight four times height in centimetres to the power zero point seven two five times weight in kilograms to the power zero point four two five. This calculator applies that closed-form equation exactly, returns BSA in square metres, and rejects non-positive height or weight so invalid anthropometrics never produce a false area.
How the Du Bois body surface area formula works
The Du Bois equation is an empirical power law fitted to measured surface areas of human subjects early in the twentieth century. It maps two positive anthropometric inputs—standing height in centimetres and body weight in kilograms—onto an estimated external body surface in square metres. Algebraically the formula is body surface area equals zero point zero zero seven one eight four multiplied by height to the exponent zero point seven two five multiplied by weight to the exponent zero point four two five.
Because the exponents are less than one, surface area grows slower than a pure product of height and weight, which matches the geometric intuition that larger people have relatively less surface per unit mass. The constant and exponents are fixed historical coefficients; this capability does not re-fit them or blend alternative tables at runtime. Inputs must be finite and strictly greater than zero: a zero or negative height or weight cannot represent a living adult body in this model and fails with invalid input rather than inventing an absolute-value workaround.
Educators often compare Du Bois against Mosteller or Haycock on the same subject; keep those formulas on separate landings when the search intent names a different equation. Always frame outputs as educational estimates derived from the published Du Bois model, not as a substitute for clinical measurement or professional judgment.
Where Du Bois BSA calculators show up in real work
Medical and nursing schools still teach the Du Bois formula when introducing body surface area for physiology labs, so a single trusted oracle that returns the classic power-law number speeds grading and demo setup. Product teams building educational health calculators need a documented Du Bois step that clients can audit by hand rather than a black-box estimate that mixes multiple formulas without disclosure. Research assistants preparing synthetic datasets for anthropometric simulations need deterministic BSA labels from height and weight without network calls or model drift.
If you later need Mosteller BSA, Haycock pediatric estimates, ideal body weight, body mass index, or basal metabolic rate equations, treat those as separate search intents and landings rather than overloading this Du Bois body surface area calculator page. Always present results as educational estimates from the nineteen sixteen Du Bois model; clinical decisions require qualified professionals, local protocols, and context this tool does not collect.
What you can do with it
Classroom BSA answer keys
Generate Du Bois square-metre values from metric height and weight so instructors and auto-graders share one transparent ground truth.
Physiology and dosing education demos
Show the classic 1916 power-law BSA step in lectures without mixing Mosteller or Haycock on the same landing.
FAQ
What units should I use for height and weight?
Height in centimetres and weight in kilograms. Convert imperial measurements before calling; the published coefficients assume metric inputs.
What happens if height or weight is zero or negative?
Non-positive anthropometrics are rejected rather than producing a meaningless surface area.
Does this implement Mosteller or other BSA formulas?
No. This capability is Du Bois only. Other formulas are separate search intents and should use their own landings.
What does it cost?
The browser tool is free and runs locally.
Why doesn't body surface area grow as fast as height and weight?
Because both exponents in the Du Bois formula are below one. Surface area rises more slowly than a plain product of height and weight, which fits the idea that larger people have relatively less surface per kilogram of mass.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/health/bsa-dubois \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"height":170,"weight":70}'const res = await fetch("https://api.kit.forhosting.com/health/bsa-dubois", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"height": 170,
"weight": 70
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/health/bsa-dubois",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"height": 170,
"weight": 70
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/health/bsa-dubois", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"height":170,"weight":70}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"height":170,"weight":70}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/health/bsa-dubois", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"height": 170,
"weight": 70
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "health.bsa_dubois",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
How the Du Bois body surface area formula works
The computation is pure floating-point arithmetic with no network calls, no random seeds, no wall-clock timestamps, and no machine-learning drift, so identical height and weight always yield identical JSON.
What you send and what you get back
Send two fields. Both fields are required. Classic smoke checks include one hundred seventy centimetres with seventy kilograms, which yields roughly one point eight one square metres, and one hundred eighty centimetres with eighty kilograms, which yields roughly two point zero zero square metres; both produce stable positive BSA values suitable for answer keys. Convert inches and pounds to centimetres and kilograms before calling if your forms collect imperial units, because the published Du Bois coefficients assume metric inputs only. Height is standing height in centimetres and must be a finite number strictly greater than zero; aliases height_cm, cm, and h are accepted. Weight is body mass in kilograms and must also be finite and positive; aliases weight_kg, kg, mass, and w are accepted. Missing fields, non-numeric strings, NaN, Infinity, zero, and negative values fail with invalid_input and are not charged. On success the response returns bsa and bsa_m2 as the same cleaned square-metre value, unit m², the cleaned height_cm and weight_kg, equation du_bois, equation_year nineteen sixteen, the formula string BSA equals zero point zero zero seven one eight four times height_cm to the zero point seven two five times weight_kg to the zero point four two five, and method du_bois. Pricing for successful API calls is the published base of $0.002 per item; validation failures do not consume prepaid balance. If a caller supplies aliases such as height_cm or weight_kg instead of the short names, the same validation and arithmetic path applies without changing the output shape.
Where Du Bois BSA calculators show up in real work
Pharmacy and oncology education modules often walk students through historical BSA-based dosing discussions; matching hand arithmetic to API output matters more than asymptotic cost even when modern practice uses additional safety checks. Because this capability is a pure parse engine, API pricing is the published base of $0.002 per successful item and failed validation does not consume balance.
Integration use cases
Deterministic anthropometric fixtures
Bulk-produce stable BSA labels for synthetic datasets and regression tests with hard invalid_input on non-positive measures.
Technical questions
What is the Du Bois body surface area formula?
BSA (m²) = 0.007184 × height_cm^0.725 × weight_kg^0.425, published by Du Bois and Du Bois in 1916. This calculator applies that equation exactly.