Calculating your body fat is straightforward once you know the Body Fat formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the Body Fat Calculator.
What is Body Fat?
The Body Fat calculation tells you your body fat from a few simple inputs. The figure you are solving for here is the body fat, expressed in percent.
The Body Fat formula
This calculation combines several inputs through a multi-step method rather than a single one-line formula. Enter the values below and the calculator resolves each step in order. The inputs it needs are:
- Gender — a number. Example: 1.
- Height — a value measured in cm. Example: 178 cm.
- Neck circumference — a value measured in cm. Example: 38 cm.
- Waist circumference — a value measured in cm. Example: 85 cm.
- Hip circumference (women) — a value measured in cm. Example: 95 cm.
How to calculate it step by step
- Write down the gender (for example, 1).
- Write down the height (for example, 178 cm).
- Write down the neck circumference (for example, 38 cm).
- Write down the waist circumference (for example, 85 cm).
- Write down the hip circumference (women) (for example, 95 cm).
- Apply the formula above to get your body fat.
- Double-check the result with the Body Fat Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Gender | 1 |
| Height | 178 cm |
| Neck circumference | 38 cm |
| Waist circumference | 85 cm |
| Hip circumference (women) | 95 cm |
| Body fat | 16.4% |
With gender of 1, height of 178 cm, neck circumference of 38 cm and waist circumference of 85 cm, the body fat works out to 16.4%.
Example 2
With gender of 1, height of 260 cm, neck circumference of 38 cm and waist circumference of 85 cm, the body fat works out to 5.5%.
| Result | Value |
|---|---|
| Body fat | 5.5% |
Example 3
With gender of 1, height of 89 cm, neck circumference of 38 cm and waist circumference of 85 cm, the body fat works out to 37.8%.
| Result | Value |
|---|---|
| Body fat | 37.8% |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
- These figures are general estimates, not medical advice — check with a qualified professional before acting on them.
Prefer not to do the maths by hand? — the Body Fat Calculator does it instantly, for free, with the formula and a worked example built in.
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