How to measure body fat at home
Two home methods give you a measured body fat number: a tape measure (the U.S. Navy method) and skinfold calipers. Both work only if you take the measurement the same way every time. Men and women measure at different sites, so pick yours below. How accurate each method is, and how it compares with smart scales and DEXA, is in how accurate is each way to measure body fat.
Before you start
- Measure at the same time of day each time, for example in the morning before you eat or train.
- Stand up straight and relaxed, arms at your sides.
- Measure on bare skin.
- Have the same person measure you each time, if someone helps.
Tape measure (U.S. Navy method)
Use a tape that does not stretch. The Army's instructions ask for fiberglass and say cloth tapes are not acceptable. These steps follow the Army's body composition regulation, which uses the same formulas (AR 600-9), and the original Navy studies (men, women). The tape touches the skin all the way round and follows the shape of the body, but does not press into it.
You need three numbers: height, neck and waist.
You need four numbers: height, neck, waist and hips.
1. Height
Stand against a wall without shoes. Measure to the nearest half inch (or centimeter).
2. Neck
Put the tape just below the larynx (the Adam's apple), not over it, at a right angle to the neck. It slopes a little down toward the front. You cannot see your own neck, so do this in front of a mirror, or ask someone to check the tape.
3. Waist
Measure at the level of the navel, with the tape parallel to the floor. Read the tape at the end of a normal, relaxed breath out. Do not pull your stomach in.
3. Waist
Measure at the narrowest part of the waist, usually about halfway between the navel and the bottom of the breastbone. Try a few heights and keep the smallest number.
4. Hips
Measure round the widest part of the buttocks, with the tape level all the way round. A side view in a mirror helps you check that it is level.
Take three rounds
Go through all the sites once, then again, then a third time, instead of measuring the neck three times in a row. If one reading differs from the others by more than 1 inch (2.5 cm), take another one. Use the average of the three closest readings for each site.
Skinfold calipers (3-site Jackson-Pollock)
The Jackson-Pollock equations use three sites, and they differ for men (men's equation) and women (women's equation). The site descriptions and the pinch technique below follow the American College of Sports Medicine's standard (ACSM). Measure on the right side of the body, standing.
Your three sites
- Chest: a diagonal fold, halfway between the front of the armpit and the nipple. A partner makes this one much easier.
- Abdomen: a vertical fold, 2 cm (about 3/4 inch) to the right of the navel.
- Thigh: a vertical fold on the front of the thigh, halfway between the top of the kneecap and the crease at the hip.
Your three sites
- Triceps: a vertical fold on the back of the upper arm, halfway between the top of the shoulder and the elbow. A partner makes this one much easier.
- Suprailiac: a diagonal fold just above the top of the hip bone, following its natural angle, in line with the front of the armpit.
- Thigh: a vertical fold on the front of the thigh, halfway between the top of the kneecap and the crease at the hip.
How to pinch and read
- Lift the fold of skin and fat between your thumb and finger, so the muscle stays below.
- Put the caliper jaws on the fold about 1 cm (1/2 inch) from your fingers, at a right angle to the fold.
- Keep pinching while you read. Read the dial 1 to 2 seconds after you let the caliper close, not later.
- Take two readings at each site, going round all the sites in turn. If the two readings at a site differ by more than 1 to 2 mm, take another.
A small pen mark on each site helps you find the same spot the next time.
Turn the measurements into a number
Enter the averages in the body fat calculator. It runs the Navy and Jackson-Pollock formulas, and shows your lean mass and the deficit the Deficit app suggests at that body fat. The calorie deficit calculator turns it into a full plan.
Frequently asked questions
How often should I measure body fat on a cut?
Once a week, on the same day, at the same time and under the same conditions. A home method is a few points off on any one day, so one week's change is mostly noise. The trend over several weeks is what counts.
Can I measure my own skinfolds?
Some sites, like the thigh and abdomen, you can reach yourself. The triceps and the chest are hard to pinch on your own body, so a partner helps. Whoever measures, keep it the same person each time.
Do I need my exact body fat percentage?
No. A number from the same method, taken the same way each time, is enough to run a cut. The change from one measurement to the next is what you use.
Sources
- Army Regulation 600-9: The Army Body Composition Program, Appendix B (circumference measurements). Headquarters, Department of the Army. 2019.
- Prediction of percent body fat for U.S. Navy men from body circumferences and height. Hodgdon JA, Beckett MB. Naval Health Research Center, Report 84-11. 1984. (DTIC)
- Prediction of percent body fat for U.S. Navy women from body circumferences and height. Hodgdon JA, Beckett MB. Naval Health Research Center, Report 84-29. 1984. (DTIC)
- Standardized description of skinfold sites and procedures. American College of Sports Medicine, Guidelines for Exercise Testing and Prescription, Box 4-1. (archived copy)
- Generalized equations for predicting body density of men. Jackson AS, Pollock ML. Br J Nutr. 1978. (PubMed)
- Generalized equations for predicting body density of women. Jackson AS, Pollock ML, Ward A. Med Sci Sports Exerc. 1980. (PubMed)
Deficit is our iOS app. It handles all of this for you, and the first week is free.
