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Browse all calculatorsEnter height and weight in metric or US units to see BSA in m² from nine formulas at once, and how far apart they are. For learning only, not for medication dosing.
Not for medication dosing. This page gives general estimates for learning. Medicine doses, including chemotherapy, are set by a prescriber or pharmacist from the prescribing information, not from a web calculator.
This is a general estimate for educational use. It is not medical advice, a diagnosis or a treatment plan. Talk to a doctor, pharmacist or other qualified professional before you make any decision about medicines or health care.
| Formula | m² | ft² | in² | vs Mosteller |
|---|
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Body surface area (BSA) is an estimate of the total area of the skin, given in square metres (m²). It is worked out from height and weight with a formula such as Mosteller, Du Bois or Haycock. This calculator shows nine formulas side by side, so you can see how far they differ for the same person.
The result updates as you type, in metric or US units, and the working shows every step for the formula you pick. The page also explains what BSA is used for in plain words. It is a general estimate for learning and is not for medication dosing. For other everyday sums, see the free online calculators.
| Height and weight | Mosteller | Du Bois | Haycock | Boyd |
|---|---|---|---|---|
| 165 cm and 65 kg | 1.73 | 1.72 | 1.73 | 1.75 |
| 180 cm and 80 kg | 2.00 | 2.00 | 2.01 | 2.01 |
| 5 ft 9 in and 155 lb | 1.85 | 1.85 | 1.85 | 1.86 |
| 120 cm and 22 kg | 0.86 | 0.86 | 0.85 | 0.87 |
The first answer is already on screen. Change any number and every formula updates at once, with no Calculate button.
Metric uses centimetres and kilograms. US uses feet, inches and pounds. Switching converts your numbers, so the same person stays on screen.
Heights from 30 to 250 cm and weights from 2 to 400 kg are accepted. Outside those limits you get a message instead of a number.
Only the Schlich formula uses sex. Pick the formula you want as the big number, Mosteller by default, and 2 or 3 decimals.
Read the table of all nine formulas and the gap between them, open the working, then copy the result or share a link with the same inputs.
W is weight in kilograms, H is height in centimetres and every result is in square metres. The coefficients are as printed in a 2016 peer-reviewed comparison of the formulas, listed under Sources.
| Formula | Equation | What the sources say |
|---|---|---|
| Mosteller (1987) | √(H × W ÷ 3600) |
New England Journal of Medicine, Simplified calculation of body-surface area. No population is stated in the sources used here. |
| Du Bois and Du Bois (1916) | 0.007184 × W^0.425 × H^0.725 |
Archives of Internal Medicine. The 2016 comparison calls it the standard formula in most medical cases. |
| Haycock (1978) | 0.024265 × W^0.5378 × H^0.3964 |
Journal of Pediatrics. The paper title reports a height-weight formula validated in infants, children and adults. |
| Gehan and George (1970) | 0.0235 × W^0.51456 × H^0.42246 |
Cancer Chemotherapy Reports. No population is stated in the sources used here. |
| Boyd (1935) | 0.0003207 × H^0.3 × G^(0.7285 − 0.0188 × log10 G), where G is weight in grams (W × 1000) |
University of Minnesota monograph, The Growth of the Surface Area of the Human Body. No population is stated in the sources used here. |
| Fujimoto (1968) | 0.008883 × W^0.444 × H^0.663 |
Nippon Eiseigaku Zasshi. The reference title indicates Japanese subjects of all ages. |
| Takahira (1925) | 0.007246 × W^0.425 × H^0.725 |
Described as a variant of Du Bois. The leading coefficient is printed as 0.007241 in another reference, a difference of under 0.1 percent. |
| Shuter and Aslani (2000) | 0.00949 × W^0.441 × H^0.655 |
European Journal of Applied Physiology, Du Bois and Du Bois revisited. |
| Schlich (2010) | Men 0.000579479 × W^0.38 × H^1.24; women 0.000975482 × W^0.46 × H^1.08 |
Ernährungs Umschau. Sex-specific, based on 3D body scans. This is the only formula that uses sex. |
At 165 cm and 65 kg the lowest and highest of the eight formulas that do not need a sex are 4.2 percent apart, measured against their average. At 75 cm and 10 kg the gap grows to 10.7 percent, and at 175 cm and 120 kg it is 8.1 percent.
Each formula is a curve fitted to a different group of people. The 2016 comparison notes that most were established on a standard adult physique, so results move apart as size moves away from the middle. The Schlich formula is left out of this table because it needs a sex, but at child sizes the calculator shows it far below the others. Tell the formula and its units whenever you quote a result.
Sizes are examples chosen to show the spread, not growth-chart values or targets. Gap is the highest value minus the lowest, divided by the average of the eight, in percent.
| Height and weight | Mosteller | Lowest | Highest | Gap |
|---|---|---|---|---|
| 50 cm, 3.5 kg | 0.22 | 0.21 (Fujimoto) | 0.23 (Gehan and George) | 12.1% |
| 75 cm, 10 kg | 0.46 | 0.43 (Fujimoto) | 0.48 (Boyd) | 10.7% |
| 115 cm, 20 kg | 0.80 | 0.78 (Fujimoto) | 0.81 (Gehan and George) | 4.3% |
| 140 cm, 35 kg | 1.17 | 1.14 (Fujimoto) | 1.18 (Takahira) | 3.5% |
| 165 cm, 65 kg | 1.73 | 1.67 (Fujimoto) | 1.75 (Boyd) | 4.2% |
| 180 cm, 80 kg | 2.00 | 1.94 (Fujimoto) | 2.01 (Takahira) | 3.5% |
| 175 cm, 120 kg | 2.42 | 2.28 (Fujimoto) | 2.48 (Boyd) | 8.1% |
Many pages ask for height and weight, let you choose one formula and show one number. These are the differences that matter when you want to understand the number.
| Feature | Basic BSA calculator | This calculator |
|---|---|---|
| Formulas | One chosen from a list | All nine at once, with the lowest, highest and the gap between them |
| Results | Often needs a Calculate button | Updates as you type, with an answer on first load |
| Units | Often one system | Metric or US input; m², ft², in² and cm² output |
| Working | Answer only | The substitution for the chosen formula, step by step |
| Child sizes | Rarely mentioned | A note on which formula states a child population, and a spread table by size |
| Safety | Often no warning beside the result | Not-for-dosing note next to the result, and limits on height and weight |
| Sharing | Rare | Copy the result, or share a link that opens with the same inputs |
A study or letter may quote BSA in m². Type the height and weight to see what each formula gives and which one comes closest to the quoted figure.
Open the working to follow each substitution and see how the exponents change the answer from one formula to the next.
Copy a result with all nine values, or share a link that opens with the same height, weight and sex, so a colleague sees the same table.
See one area in m², ft², in² and cm² together, with height and weight entered in metric or in feet, inches and pounds.
Enter the same height and weight as your own sheet and compare each formula. A mismatch often points to a mistyped coefficient.
Enter a small height and weight to watch the formulas drift apart. For an actual child, a clinician or pharmacist decides which method applies. Age is not used by any formula; the age calculator works out an age from a birth date.
In plain words, BSA describes body size with one number, and it is used where size matters more than weight alone. These are the uses named in the references on this page.
Not for medication dosing. This calculator gives general estimates for learning. Medicine doses, including chemotherapy, are set by a prescriber or pharmacist from the prescribing information and a measured height and weight, not from a web calculator.
Some body measurements are divided by BSA so people of different sizes can be compared. Reference works list cardiac output divided by BSA, which is the cardiac index, and kidney clearance reported per 1.73 m².
Burn size is given as a percentage of total body surface area, which is used in planning burn treatment.
BSA is used by clinicians to scale some doses, chemotherapy being the best-known case, and the 2016 comparison describes it as the main use. That is the reason this page carries a not-for-dosing note.
The literature also names liver volume indexing in transplant work and dose scaling in veterinary and regulatory settings.
BSA says how large a body is, not how healthy or fit it is. For body composition estimates, see the body fat calculator and the lean body mass calculator.
The nine formulas can differ by several percent, so quote a result with its formula name, for example 1.73 m² (Mosteller). To find the percentage difference between two of your own figures, use the percentage calculator.
It does not calculate or check any medicine dose. Doses of chemotherapy and other medicines are decided by a prescriber or pharmacist from the prescribing information.
Every formula estimates skin area from height and weight. The 2016 comparison in Scientific Reports found that published formulas give noticeably different results for the same person, and reference articles say values are less accurate at extremes of height and weight.
Coefficients are as printed in that comparison; Takahira appears as 0.007241 in another reference, under 0.1 percent apart. Heights outside 30 to 250 cm and weights outside 2 to 400 kg get a message, not a number.
The equations, the list of uses and the notes on accuracy come from the pages opened for this page. The original papers are cited in them: Du Bois and Du Bois, Archives of Internal Medicine 1916;17:863-871; Mosteller, New England Journal of Medicine 1987;317:1098; Haycock, Schwartz and Wisotsky, Journal of Pediatrics 1978;93:62-66; Gehan and George, Cancer Chemotherapy Reports 1970;54:225-235; Shuter and Aslani, European Journal of Applied Physiology 2000;82:250-254; Schlich, Schumm and Schlich, Ernährungs Umschau 2010;57:178-183. The original papers were not opened for this page, so coefficients come from the first source below and were compared with the second wherever it prints them.
Short answers about BSA, the formulas and the limits of this calculator.
Body surface area (BSA) is an estimate of the total area of the skin, given in square metres. It is not measured directly in everyday life; it is worked out from height and weight with a formula such as Mosteller or Du Bois.
With the Mosteller formula, multiply height in centimetres by weight in kilograms, divide by 3,600 and take the square root. For 165 cm and 65 kg that is 165 × 65 = 10,725, divided by 3,600 is 2.9792, and the square root is 1.7260, so BSA is 1.73 m².
No single formula is the most accurate for everyone. A 2016 comparison of the published formulas in Scientific Reports found that they give noticeably different results for the same person, and it names Du Bois as the one most often chosen in medical work. Mosteller is the simplest to do by hand, and Haycock is the one whose paper reports validation in infants, children and adults.
Each formula is a curve fitted to a different group of people, so it leans towards the body shapes in its own data. For the eight formulas that do not need the sex, the gap between the lowest and highest is about 4.2 percent of their average at 165 cm and 65 kg, but about 10.7 percent at 75 cm and 10 kg.
No. This page is for learning and gives general estimates only. Some medicines are prescribed per square metre of BSA, but those doses are set by a prescriber or pharmacist from the prescribing information and a measured height and weight, not from a web calculator.
Of the sources used for this page, only Haycock reports validation in infants, children and adults, and Fujimoto is described as covering Japanese subjects of all ages. The sources do not state a child population for the others, so their child-size results are extrapolation. A clinician or pharmacist decides which method applies to a child.
None of the nine formulas uses age. Only the Schlich formula uses sex, with separate coefficients for men and women, which is why the sex buttons affect only that row. Choose Not stated to leave Schlich out of the table and the range.
There is no target value. BSA is a measure of size, not of health, and it grows with height and weight. Reference articles list group averages by age and sex, but a number above or below an average says nothing about an individual.
Divide square metres by 0.09290304 for square feet, or by 0.00064516 for square inches. Multiply by 10,000 for square centimetres. The calculator shows all of these units for the headline result.
Tap US under Units, then type feet and inches in the two height boxes, for example 5 and 9. The calculator multiplies the total inches by 2.54 and the pounds by 0.45359237 before using the formulas, and the working shows those steps.
Heights from 30 to 250 cm (about 11.8 to 98.4 inches) and weights from 2 to 400 kg (about 4.4 to 881.8 lb). Outside those limits it shows a message instead of a number, because the formulas were fitted to people, not to values far beyond the sizes in their data.
No. The calculation runs in your browser and nothing is sent to a server. The numbers appear in the page address only after you change a value or tap Share link, and only your choice of metric or US units is remembered on your own device.