Body fat scanners cost hundreds of pounds, but several reliable formulas estimate body fat percentage from simple measurements. Here's how to use the most accurate methods at home.
DEXA scans are the gold standard for body composition measurement — but at £50–100 per scan, most people rely on estimates. Several validated formulas produce surprisingly accurate results from measurements you can take at home.
Developed by the US Navy, validated across large populations, and considered the most practical tape-measure method.
Less accurate than tape measurements but only requires height, weight, and age:
Tape measure methods have a margin of error of ±3–4% compared to DEXA. They're best used for tracking trends over time rather than point-in-time accuracy. A consistent measuring technique is more important than the formula used — measure at the same time of day (morning is best), take three measurements and average them, and use the same measuring tape each time.
Consumer body fat scales (including most Fitbit, Garmin, and smart scales) use bioelectrical impedance — they send a small current through your body and estimate fat from resistance. Accuracy is genuinely poor (±5–8%) and varies enormously with hydration, recent exercise, and food consumption. Tape measure methods are more reliable for most people.