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A fit adult couple using a skinfold caliper to measure the man’s chest in a gym.

Measure. Understand. Track.

Body FatCaliper Calculator

Turn your skinfold measurements into a body-fat estimate. Choose your test, take three readings, and follow your progress.

Your measurements

All folds in mm
Equation
Choose your test

Men’s equation: ages 18–61.

Measure in rounds: take reading 1 at every site, then repeat for readings 2 and 3. Let the skin recover between pinches.

Jackson–Pollock method · Three readings averaged per site

Your estimated body fat

Your result starts here

Choose your test and enter three readings at every site. Add your weight to also estimate fat mass and lean mass.

Saved results stay on this device and browser. They do not sync across devices or with your account. Clearing browser data removes them. Anyone using this browser may be able to view them.

Before you start

  1. Use skinfold calipers and ask a helper, especially for the back and upper-arm sites.
  2. Measure the right side with relaxed muscles and dry skin, before exercise.
  3. Locate and mark the site. Pinch skin and fat away from muscle; hold the pinch throughout the reading.
  4. Place the jaws about 1 cm from your fingers, perpendicular to the fold. Read after 1–2 seconds.
  5. Release the caliper, then the pinch. Rotate through the sites for three rounds.

The hero photo is illustrative. Follow each site’s written landmarks and fold direction.

Know what the number means

How reliable are calipers?

Useful for tracking trends

Use the same tester, calipers, method and conditions. Compare changes over time instead of chasing a single number. Track the sum of skinfolds alongside the estimated percentage.

Expect some uncertainty

Published prediction errors are roughly 3–4 body-fat percentage points under suitable conditions. Individual errors can be larger; this is not a guaranteed error range for your result.

More sites ≠ guaranteed accuracy

Seven sites cover more areas, but correct placement and repeatable technique matter more than site count alone. Three similar readings cannot fix a pinch taken at the wrong location.

Which sites are used?

Men’s 3-site test: chest, abdomen and thigh. Women’s 3-site test: triceps, suprailiac and thigh. Both 7-site tests: chest, midaxillary, triceps, subscapular, abdomen, suprailiac and thigh. The equations differ for men and women.

Why take three readings at every site?

Repeats reveal inconsistent measurements. The calculator uses the arithmetic average of all three readings at each site, adds the site averages, then calculates body density and estimated body fat. It suggests remeasuring when the largest and smallest readings at a site differ by more than 2 mm. Replace questionable readings after checking the location and technique.

Who is this calculator intended for?

The original studies covered men aged 18–61 and women aged 18–55; this calculator stays within those age ranges. These are historical sex-specific equations, and their accuracy varies by population, fat distribution and body composition. They are not validated for every individual or for changes associated with gender-affirming hormone therapy. They are not intended for children or pregnancy. Very lean individuals, people with higher body fat, or anyone unable to obtain a reliable fold should seek an appropriate professional assessment.

Does lean mass mean muscle mass?

No. Lean mass includes water, bones, organs and other non-fat tissue as well as muscle. Estimated fat mass equals weight × body-fat percentage; lean mass equals weight minus estimated fat mass. Weight is optional and does not affect the body-fat percentage.

How often should I compare results?

Use a consistent schedule and similar conditions, and look at trends across several tests. Avoid interpreting small day-to-day differences as fat gain or loss. Do not directly compare a 3-site skinfold sum with a 7-site sum, or treat results from different methods as interchangeable.

How do printing and saving work?

Print / PDF opens your browser’s print window. Choose a printer or Save as PDF. The report includes the date, equation, readings, averages, results and measurement cautions. Save result stores up to 50 tests in this browser only; storage may be unavailable or temporary in private browsing. You can open, print or delete saved tests. Download a PDF if you want a portable copy.

Formulas and references

We use the Jackson–Pollock men’s and Jackson–Pollock–Ward women’s equations to estimate body density, followed by the Siri conversion: body fat (%) = 495 ÷ density − 450. S is the sum of the site averages in millimetres; A is age in years. Full precision is retained until results are displayed.

  • Men, 3-site: D = 1.10938 − 0.0008267S + 0.0000016S² − 0.0002574A
  • Women, 3-site: D = 1.0994921 − 0.0009929S + 0.0000023S² − 0.0001392A
  • Men, 7-site: D = 1.112 − 0.00043499S + 0.00000055S² − 0.00028826A
  • Women, 7-site: D = 1.097 − 0.00046971S + 0.00000056S² − 0.00012828A

For adult educational use. This estimate does not diagnose health conditions or measure visceral fat. Body-fat percentage is only one part of overall health and fitness.