Comprehensive Calculator Guide
This calculator works out your body fat from three skinfold caliper measurements, using the Jackson–Pollock method common in gyms and clinics. A 30-year-old man with chest 12 mm, abdomen 20 mm and thigh 15 mm comes out at 14.2% body fat. Add your weight to see how many kilos of fat you carry and your lean weight.
How it works and how to measure
About half of body fat sits under the skin, so its thickness at set points predicts the total. Jackson and Pollock’s equations turn the sum of skinfolds and your age into body density; the Siri equation then gives body fat: 495 ÷ density − 450.
Men: chest, abdomen, thigh. Women: triceps, suprailiac, thigh. Measure the right side, relaxed; pinch the skin off the muscle, set the caliper a centimetre from your fingers, read after two seconds, and average two or three readings.
How to Use
- Choose your sex and enter your age.
- Enter the three skinfolds in millimetres, and your weight if you want fat in kilos.
- Press “Calculate body fat” to see the sum, body density, body fat and its band.
Formula Used
Men: D = 1.10938 − 0.0008267S + 0.0000016S² − 0.0002574×age | Women: D = 1.0994921 − 0.0009929S + 0.0000023S² − 0.0001392×age | Fat % = 495 ÷ D − 450
Practical Examples
- Example 1
- Man, 30, folds 12/20/15 mm, 80 kg: density 1.0663, 14.2% fat, 11.4 kg fat.
- Example 2
- Woman, 28, folds 18/14/25 mm: density 1.0465, 23% fat.
Important Tips
- Have the same person measure you each time.
Common Mistakes to Avoid
- Pinching muscle along with the skin.
Frequently Asked Questions
- How do I calculate body fat with calipers?
- Add three skinfolds and apply the Jackson–Pollock and Siri equations, as this calculator does.
- How accurate are skinfolds?
- Within about 3–4% with a trained measurer and a good caliper; less so with severe obesity.
- What is a good body fat for men?
- 14–17% is fit, 18–24% average, 25%+ high (ACE).