A practical estimate you can do at home. Pick your method, enter the required measurements, and get your % body fat.
How to measure correctly
The biggest source of error is technique. The goal is not a perfect number - it’s a repeatable method you can track over time.
There’s no single perfect “body fat test” at home. These calculators use statistical models that turn measurements into an estimate. If you use the same method, same landmarks, and similar conditions, the result is very useful for tracking trends.
Uses height plus body circumferences (neck/waist, and hip for women). It works surprisingly well for many people because waist-to-neck ratios correlate with overall fatness. It can be less accurate if fat distribution is unusual or if measurements are inconsistent.
Measures skinfold thickness at three standardized sites (different for men and women). It estimates body density and converts it to body fat %. Accuracy depends heavily on technique, consistent pinch location, and averaging multiple readings.
This tool estimates your body fat percentage using two commonly-used home approaches: tape measurements (US Navy) and skinfold calipers (Jackson‑Pollock 3‑site). It’s meant for tracking trends over time - not for diagnosing health conditions.
The tape method here uses the US Navy equations. They require neck + waist (and hip for women) because they model body fat from how fat is distributed around the torso. Without those measurements, the formula can’t be computed in a meaningful way.
The US Navy equations estimate body fat from a few circumferences because fat changes the shape of the torso. Waist reflects abdominal fat; neck helps “anchor” the model so two people with the same waist but different builds aren’t treated the same.
Height is included to normalise the measurements: the same waist means something different on someone who is much taller or shorter. For women, hip circumference is added because lower‑body fat distribution can shift results.
The formula uses logarithms, so small differences in the tape can move the result. That’s why repeatability (same landmark, same tension, same posture) matters more than obsessing over a single “perfect” number.
Tape is less reliable if you carry fat very differently from the average person the equations were built on (very muscular neck/shoulders, very high obesity, extreme leanness). Bloating, big meals, and inconsistent tape tension also add noise. Use it mainly to track trends under the same conditions.
Skinfold calipers measure the thickness of subcutaneous fat at specific sites. Jackson‑Pollock 3‑site uses those readings to estimate body density, which is then converted to % body fat using the Siri equation.
It works because, for many people, subcutaneous fat at standardised sites correlates with total body fat. But it’s a model: it assumes a typical relationship between subcutaneous and internal fat, and a typical body composition.
Technique is everything: correct site location, a proper pinch, caliper placement and timing (reading after ~1–2 seconds) can easily change the result by several percentage points.
Calipers struggle if you can’t get a clean pinch (very high body fat), if measurements are taken right after training/heat, or if site location is inconsistent. Inter‑tester differences are common. If possible, have the same person measure you each time and average 2–3 repeats per site.
Measure at the same time of day, after a normal exhale, before training, and with stable hydration. Do 2–3 repeats and use the average. Use the same units, the same method and the same landmarks every time. Consistency beats “perfect”.
It’s an estimate based on population data. For many people it’s “accurate enough” to track changes, especially if you measure consistently. If your fat distribution is unusual, results can be biased - use it mainly for trends, not absolute precision.
Yes. Both methods on this page work without body weight. Tape uses circumferences; calipers use skinfold thickness. You still need height.
Tape is simpler and often more repeatable. Calipers can be more sensitive if your technique is consistent. Pick one method and stick with it.
They use different models and assumptions. Fat distribution, hydration and technique can shift results. Pick one method and repeat it consistently.
Double-check units, re-measure carefully, and average 2–3 repeats. If you recently trained, ate a big meal, or are dehydrated, wait and measure again under normal conditions.
Every 2–4 weeks is a good balance. More often can be noisy due to water retention and measurement variability.
Disclaimer: educational purposes only. Not medical advice. If you have a medical condition, talk to a qualified professional.