Which body fat method is most accurate?

Of the four here, the 7-site skinfold method, when the calipers are used consistently by someone who knows how. But none of them measures body fat — they all estimate it from proxies. DXA is the practical reference standard, and even that varies between machines.

Why does the US Navy method need my neck measurement?

The equation works from the difference between waist and neck girth. The neck acts as a proxy for frame size, so two people with the same waist but different builds do not get the same answer. It is also why a neck measured larger than the waist produces no result: the equation takes a logarithm of that difference.

How accurate is the tape method?

Hodgdon and Beckett reported a correlation around 0.90 against hydrostatic weighing, with a typical error of three to four percentage points. So a reading of 20% is realistically somewhere between 16% and 24%. Treat it as a band, and track the direction it moves over time rather than the single figure.

What is a healthy body fat percentage?

Published reference ranges vary by source and by age, and there is no single agreed cut-point the way there is for BMI. Essential fat is around 3% for men and 12% for women, below which health suffers. Beyond that, this site does not publish target ranges, because a target number invites chasing it.

Why is there no result under 18?

All four equations were derived from and validated on adults. Body composition during growth depends on developmental stage in ways these equations do not model, so applying them to a 15-year-old produces a number with no meaning behind it.

Do I measure my waist at the navel or the narrowest point?

For the US Navy method: men measure at the navel, women at the narrowest point. That asymmetry is in the original protocol, not a mistake — the two equations were derived against measurements taken that way, so using a different site changes the answer.

Body fat percentage calculator

Four published methods, in descending order of how much they actually measure. The US Navy method needs only a tape measure, which is why it is the default.

Result

These are estimates from population-level equations, not a measurement of you and not medical advice. Individual results vary widely. Talk to a doctor or a registered dietitian before making significant changes to how you eat or train.

How this is calculated

US Navy circumference methoddefault

              men:   %BF = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
women: %BF = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
(measurements in inches)

Source: Hodgdon JA, Beckett MB. Naval Health Research Center Reports 84-11 (men) and 84-29 (women), San Diego, 1984.
Assumes: That the distribution of fat around the waist and neck is representative of total body fat. It was derived on US Navy personnel.
Accuracy: Typical error of three to four percentage points against hydrostatic weighing, with a correlation around 0.90. The best accuracy available to someone holding only a tape measure, which is why it is the default.

Jackson-Pollock, 7 sites

              men:   BD = 1.112 − 0.00043499·S + 0.00000055·S² − 0.00028826·age
women: BD = 1.097 − 0.00046971·S + 0.00000056·S² − 0.00012828·age
%BF = 495 / BD − 450        (S = sum of 7 skinfolds, mm)

Source: Jackson AS, Pollock ML, British Journal of Nutrition 40(3), 1978; Jackson AS, Pollock ML, Ward A, Medicine and Science in Sports and Exercise 12(3), 1980. Density converted by Siri WE, 1961.
Assumes: That fat mass has a density of 0.900 g/cm³ and fat-free mass 1.100 g/cm³ — constants derived from a small, young reference population.
Accuracy: The most accurate of the four when the calipers are used correctly, and the most dependent on technique. Measurement error at seven sites compounds, so an inconsistent pinch matters more here than anywhere else.

Jackson-Pollock, 3 sites

              men:   BD = 1.10938 − 0.0008267·S + 0.0000016·S² − 0.0002574·age
women: BD = 1.0994921 − 0.0009929·S + 0.0000023·S² − 0.0001392·age
%BF = 495 / BD − 450        (S = sum of 3 skinfolds, mm)

Source: Jackson AS, Pollock ML, British Journal of Nutrition 40(3), 1978; Jackson AS, Pollock ML, Ward A, Medicine and Science in Sports and Exercise 12(3), 1980.
Assumes: The same density constants as the 7-site equation.
Accuracy: Slightly less accurate than the 7-site version and considerably more practical. For most people the difference between the two is smaller than the error introduced by inconsistent caliper technique.

Deurenberg (BMI-based)

              %BF = 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4
(sex: male = 1, female = 0)

Source: Deurenberg P, Weststrate JA, Seidell JC, British Journal of Nutrition 65(2), 1991, pp. 105–114.
Assumes: That body fat can be inferred from BMI, age and sex alone, with no direct measurement of the body.
Accuracy: The least accurate of the four, and it inherits every limitation of BMI because BMI is its only body input. It over-reads substantially for muscular people. Included because it is widely cited and needs no tape measure.

Which formula should you use

This page defaults to US Navy circumference method. Typical error of three to four percentage points against hydrostatic weighing, with a correlation around 0.90. The best accuracy available to someone holding only a tape measure, which is why it is the default.

Jackson-Pollock, 7 sites — The most accurate of the four when the calipers are used correctly, and the most dependent on technique. Measurement error at seven sites compounds, so an inconsistent pinch matters more here than anywhere else.
Jackson-Pollock, 3 sites — Slightly less accurate than the 7-site version and considerably more practical. For most people the difference between the two is smaller than the error introduced by inconsistent caliper technique.
Deurenberg (BMI-based) — The least accurate of the four, and it inherits every limitation of BMI because BMI is its only body input. It over-reads substantially for muscular people. Included because it is widely cited and needs no tape measure.

US Navy body fat by waist and neck, men at 178 cm

The method works from the difference between waist and neck, so a larger neck at the same waist reads lower. Typical error against hydrostatic weighing is three to four percentage points.

US Navy body fat by waist and neck, men at 178 cm
Waist	35 cm	38 cm	41 cm
75 cm	10.5%	7.6%	4.4%
80 cm	14.9%	12.3%	9.5%
85 cm	18.8%	16.5%	14%
90 cm	22.4%	20.3%	18%
95 cm	25.6%	23.7%	21.7%
100 cm	28.6%	26.8%	25%
105 cm	31.4%	29.7%	28%

Questions

Which body fat method is most accurate?: Of the four here, the 7-site skinfold method, when the calipers are used consistently by someone who knows how. But none of them measures body fat — they all estimate it from proxies. DXA is the practical reference standard, and even that varies between machines.
Why does the US Navy method need my neck measurement?: The equation works from the difference between waist and neck girth. The neck acts as a proxy for frame size, so two people with the same waist but different builds do not get the same answer. It is also why a neck measured larger than the waist produces no result: the equation takes a logarithm of that difference.
How accurate is the tape method?: Hodgdon and Beckett reported a correlation around 0.90 against hydrostatic weighing, with a typical error of three to four percentage points. So a reading of 20% is realistically somewhere between 16% and 24%. Treat it as a band, and track the direction it moves over time rather than the single figure.
What is a healthy body fat percentage?: Published reference ranges vary by source and by age, and there is no single agreed cut-point the way there is for BMI. Essential fat is around 3% for men and 12% for women, below which health suffers. Beyond that, this site does not publish target ranges, because a target number invites chasing it.
Why is there no result under 18?: All four equations were derived from and validated on adults. Body composition during growth depends on developmental stage in ways these equations do not model, so applying them to a 15-year-old produces a number with no meaning behind it.
Do I measure my waist at the navel or the narrowest point?: For the US Navy method: men measure at the navel, women at the narrowest point. That asymmetry is in the original protocol, not a mistake — the two equations were derived against measurements taken that way, so using a different site changes the answer.

Calculators

Guides

Last reviewed August 20, 2026. Category: Body composition.