Body Surface Area Calculator

Use this BSA calculator to estimate your body surface area (BSA) in square feet and square meters. Useful for a number of health/fitness calculations.

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    Quick navigation:
  1. What is BSA?
  2. Estimating Body Surface Area (BSA)
  3. BSA applications

    What is BSA?

Body Surface Area (BSA) is simply a measurement of the surface area of your body. Since the body is a complex figure, making an accurate measurement of its surface is a considerable challenge. To address it, scientists in the early 1900s took measurements via melted paraffin and paper strips applied to their body. After removing the pieces, they were cut into regular shapes allowing accurate BSA calculation.

From these studies we have understanding of the relationship between height (stature) and body weight (mass) and a formula through which we can calculate a persons body surface area based in their weight and height. BSA calculations are useful when determining different body characteristics, for example energy expenditure in the form of BMR, RMR (REE), RDEE, TDEE, which are in turn used when determining dietary and nutritional needs.

    Estimating Body Surface Area (BSA)

To estimate your body surface area our BSA calculator uses the following formula[1]:

0.20247 x height (m)0.725 x mass (kg)0.425

where height is in meters and mass is in kg. The result is in squared meters, which easily be converted to square feet, inches or yards as needed. Below are some average values for different age groups in graph and table form.

This is a slight variation of the DuBois & DuBois body surface area formula, derived in 1916 [4], modified for easier calculation with height expressed in meters instead of centimeters and the results are practically identical. The DuBois & DuBois original formula is:

0.007184 x height (cm)0.725 x mass (kg)0.425

There are other competing formulae derived over the years (e.g. Breitmann in 1932, Stevenson in 1937, Haycock in 1978, Schlich in 2010) and a discussion about their accuracy is ongoing in the medical community, but the formula used in our BSA calculator is one of the most-commonly used by medical practitioners [3].

Both the chart and the tables with average body surface area estimates are based on weight and height data from the U.S. NCHS National Health and Nutrition Examination Survey (2011-2014) [2].

bsa age gender

The graph clearly shows that values for boys and girls are almost identical up to 14 years of age, when they significantly departure with males having a mean BSA 10-15% higher than females due to differences in stature and weight (there is no gender component in the formula).

Mean male BSA by age table:

Mean (average) BSA for males by age
Age or age groupBSA (m2)BSA (ft2)
Neonate (newborn) 0.243 m2 2.612 ft2
1 years 0.467 m2 5.027 ft2
2 years 0.563 m2 6.060 ft2
3 years 0.634 m2 6.824 ft2
4 years 0.712 m2 7.664 ft2
5 years 0.787 m2 8.471 ft2
6 years 0.867 m2 0.332 ft2
7 years 0.965 m2 10.387 ft2
8 years 1.050 m2 11.302 ft2
9 years 1.116 m2 12.013 ft2
10 years 1.236 m2 13.304 ft2
11 years 1.371 m2 14.757 ft2
12 years 1.435 m2 15.446 ft2
13 years 1.603 m2 17.255 ft2
14 years 1.720 m2 18.514 ft2
15 years 1.825 m2 19.644 ft2
16 years 1.886 m2 20.301 ft2
17 years 1.907 m2 20.527 ft2
18 years 1.980 m2 21.313 ft2
19 years 1.958 m2 21.076 ft2
20-29 years 2.016 m2 21.700 ft2
30-39 years 2.072 m2 22.303 ft2
40-49 years 2.081 m2 22.340 ft2
50-59 years 2.070 m2 22.281 ft2
60-69 years 2.065 m2 22.227 ft2
70-79 years 1.998 m2 21.506 ft2
80+ years 1.920 m2 20.667 ft2

Mean female BSA by age table:

Mean (average) BSA for females by age
Age or age groupBSA m2BSA ft2
Neonate (newborn) 0.234 m2 2.519 ft2
1 years 0.456 m2 4.908 ft2
2 years 0.540 m2 5.813 ft2
3 years 0.625 m2 6.727 ft2
4 years 0.702 m2 7.556 ft2
5 years 0.771 m2 8.299 ft2
6 years 0.862 m2 9.278 ft2
7 years 0.942 m2 10.140 ft2
8 years 1.051 m2 11.313 ft2
9 years 1.163 m2 12.518 ft2
10 years 1.245 m2 13.401 ft2
11 years 1.361 m2 14.650 ft2
12 years 1.512 m2 16.275 ft2
13 years 1.550 m2 16.684 ft2
14 years 1.621 m2 17.448 ft2
15 years 1.685 m2 18.137 ft2
16 years 1.698 m2 18.277 ft2
17 years 1.727 m2 18.589 ft2
18 years 1.726 m2 18.579 ft2
19 years 1.741 m2 18.740 ft2
20-29 years 1.790 m2 19.267 ft2
30-39 years 1.845 m2 19.859 ft2
40-49 years 1.842 m2 19.827 ft2
50-59 years 1.840 m2 19.806 ft2
60-69 years 1.804 m2 19.418 ft2
70-79 years 1.780 m2 19.160 ft2
80+ years 1.638 m2 17.631 ft2

Body surface area in squared meters and squared feet in the graph and tables is calculated using our body surface area calculator. It should be noted that the mean and the median values, at least for children and adolescents of age 0-20 differ significantly, with the median being significantly lower than the mean, suggesting that the distribution is affected by a relatively small number of overweight and obese individuals. Take this into account when interpreting the data.

    BSA applications

Body surface area is used to calculate the resting energy expenditure, also known as resting metabolic rate when the rate required is per square meter per hour, and not the daily rate. The same applies for total daily energy expenditure calculations.

BSA is also used to determine the dosage of medications, to estimate renal clearance, in chemotherapy dosage, glucocorticoid dosage and in the composition of the cardiac index. Several antivirals, antimicrobials, and antifungals require a dosing regimen based on the BSA [3]. Estimations related to organ transplantation often use the body surface area as an important metric.


[1] Katch V.L., McArdle W.D., Katch F.I (2011) "Essentials of Exercise Physiology", fourth edition

[2] US NCHS (2016) "National Health and Nutrition Examination Survey (2011-2014)" DHHS Publication No. 1604, s.3, N 39

[3] Redlarski G., Palkowski A., Krawczuk M. (2016) "Body surface area formulae: an alarming ambiguity" Scientific Reports 6, article 27966

[4] Du Bois D. & Du Bois E.F. (1916) "A formula to estimate the approximate surface area if height and weight be known." Archives of Internal Medicine 17:863–871

Cite this calculator & page

If you'd like to cite this online calculator resource and information as provided on the page, you can use the following citation:
Georgiev G.Z., "Body Surface Area Calculator", [online] Available at: URL [Accessed Date: 01 Apr, 2023].