Body Fat Calculator
Estimate body fat percentage with the US Navy tape-measure method.
Your result
Updates as you type. Based on 2025/26 UK figures where relevant.
How this is worked out
The US Navy formula uses height, neck and waist (plus hips for women) measured in centimetres. It's an estimate; DEXA scans are more accurate.
Tips
- The NHS uses BMI as a screening tool, but waist measurement also matters.
- Estimates like BMR and body fat can vary by 5–10% from lab measurements.
- Track trends over weeks rather than day-to-day changes.
Guides for this calculator
- How to Calculate Body Fat Percentage in the UK: Step-by-Step Guide
- Body Fat Percentage: Common Mistakes, Tips and FAQs
More health and fitness calculators
Frequently asked questions
How does the body Fat Calculator work?
The US Navy formula uses height, neck and waist (plus hips for women) measured in centimetres. It's an estimate; DEXA scans are more accurate.
Is this medical advice?
No. These tools give general estimates. For medical advice, speak to your GP, pharmacist or NHS 111.
Can I use these for children?
No. Children's BMI and health measures use age- and sex-specific charts. Use the NHS healthy weight calculator for children.
Why use stone and pounds?
Many people in the UK still think in stone and pounds, so we accept those units and show metric too.
This calculator gives an estimate for general information. It isn't financial, tax, legal or medical advice. Check official figures on GOV.UK or NHS.uk, or speak to a qualified adviser.