Body Fat from Skinfolds
Enter each skinfold in millimetres. The folds are added up and run through the equation, and the result lights up on a chart of every skinfold sum by age — coloured Lean, Ideal, Average and Overfat — so you can see at a glance where it sits.
The everyday standard. Three folds, with different sites for men and women. Good to roughly ±3.5% for most people.
Skinfolds (mm)
3 sites · tap a name for where to pinch
Enter the age and every skinfold above to see the result on the chart.
| Sum mm \ Age | Up to 20 | 21-25 | 26-30 | 31-35 | 36-40 | 41-45 | 46-50 | 51-55 | 56 & up |
|---|---|---|---|---|---|---|---|---|---|
| 10–14 | 2.0 | 2.6 | 3.1 | 3.6 | 4.2 | 4.7 | 5.2 | 5.8 | 6.5 |
| 15–19 | 3.6 | 4.2 | 4.7 | 5.3 | 5.8 | 6.3 | 6.9 | 7.4 | 8.2 |
| 20–24 | 5.2 | 5.8 | 6.3 | 6.9 | 7.4 | 8.0 | 8.5 | 9.0 | 9.8 |
| 25–29 | 6.8 | 7.4 | 7.9 | 8.4 | 9.0 | 9.5 | 10.1 | 10.6 | 11.4 |
| 30–34 | 8.4 | 8.9 | 9.5 | 10.0 | 10.6 | 11.1 | 11.7 | 12.2 | 13.0 |
| 35–39 | 9.9 | 10.4 | 11.0 | 11.5 | 12.1 | 12.7 | 13.2 | 13.8 | 14.6 |
| 40–44 | 11.4 | 11.9 | 12.5 | 13.1 | 13.6 | 14.2 | 14.7 | 15.3 | 16.1 |
| 45–49 | 12.9 | 13.4 | 14.0 | 14.5 | 15.1 | 15.7 | 16.2 | 16.8 | 17.6 |
| 50–54 | 14.3 | 14.9 | 15.4 | 16.0 | 16.6 | 17.1 | 17.7 | 18.3 | 19.1 |
| 55–59 | 15.7 | 16.3 | 16.9 | 17.4 | 18.0 | 18.6 | 19.1 | 19.7 | 20.5 |
| 60–64 | 17.1 | 17.7 | 18.3 | 18.8 | 19.4 | 20.0 | 20.6 | 21.1 | 22.0 |
| 65–69 | 18.5 | 19.1 | 19.7 | 20.2 | 20.8 | 21.4 | 22.0 | 22.5 | 23.4 |
| 70–74 | 19.9 | 20.4 | 21.0 | 21.6 | 22.2 | 22.7 | 23.3 | 23.9 | 24.7 |
| 75–79 | 21.2 | 21.7 | 22.3 | 22.9 | 23.5 | 24.1 | 24.7 | 25.2 | 26.1 |
| 80–84 | 22.5 | 23.0 | 23.6 | 24.2 | 24.8 | 25.4 | 26.0 | 26.6 | 27.4 |
| 85–89 | 23.7 | 24.3 | 24.9 | 25.5 | 26.1 | 26.6 | 27.2 | 27.8 | 28.7 |
| 90–94 | 24.9 | 25.5 | 26.1 | 26.7 | 27.3 | 27.9 | 28.5 | 29.1 | 29.9 |
| 95–99 | 26.1 | 26.7 | 27.3 | 27.9 | 28.5 | 29.1 | 29.7 | 30.3 | 31.1 |
| 100–104 | 27.3 | 27.9 | 28.5 | 29.1 | 29.7 | 30.3 | 30.9 | 31.5 | 32.3 |
| 105–109 | 28.4 | 29.0 | 29.6 | 30.2 | 30.8 | 31.4 | 32.0 | 32.6 | 33.5 |
| 110–114 | 29.5 | 30.1 | 30.7 | 31.3 | 31.9 | 32.6 | 33.2 | 33.8 | 34.6 |
| 115–119 | 30.6 | 31.2 | 31.8 | 32.4 | 33.0 | 33.6 | 34.2 | 34.9 | 35.7 |
| 120–124 | 31.7 | 32.3 | 32.9 | 33.5 | 34.1 | 34.7 | 35.3 | 35.9 | 36.8 |
| 125–129 | 32.7 | 33.3 | 33.9 | 34.5 | 35.1 | 35.7 | 36.3 | 36.9 | 37.8 |
Formulas
JP3 men (chest, abdomen, thigh): D = 1.10938 − 0.0008267·S + 0.0000016·S² − 0.0002574·age
JP3 women (triceps, suprailiac, thigh): D = 1.0994921 − 0.0009929·S + 0.0000023·S² − 0.0001392·age
JP7 men: D = 1.112 − 0.00043499·S + 0.00000055·S² − 0.00028826·age
JP7 women: D = 1.097 − 0.00046971·S + 0.00000056·S² − 0.00012828·age
Durnin–Womersley: D = c − m · log₁₀(S) (c, m by sex and age band)
Siri: Body fat % = 495 ÷ D − 450
Lean mass = weight × (1 − body fat % ÷ 100)
Band (Lean / Ideal / Average / Overfat) = the caliper chart’s range for that age
How It Works
S is the sum of the skinfolds in millimetres and D is body density. Every equation estimates density, and Siri converts density to a percentage. Expect roughly ±3–4% against DEXA — reliable for trends when the same tester uses the same sites and method each time.
Sources
- Jackson AS, Pollock ML (1978). Br J Nutr 40(3):497–504.
- Jackson AS, Pollock ML, Ward A (1980). Med Sci Sports Exerc 12(3):175–181.
- Durnin JVGA, Womersley J (1974). Br J Nutr 32(1):77–97.
- Siri WE (1961). Body composition from fluid spaces and density. In: Techniques for Measuring Body Composition.
Questions
How accurate is skinfold body fat testing?
Roughly within 3–4 percentage points of DEXA when performed by a trained tester. It is best used for tracking change over time with the same tester, sites and equation.
Should I use the 3-site or 7-site Jackson–Pollock method?
The 3-site method is quicker and every site can be reached on yourself. The 7-site method is slightly less sensitive to one bad pinch but needs a second person for the back sites.
From Classroom to Clients
When your students start coaching, TrainerQ runs these same calculations on real clients — with programs, progress reports and bookings in one place. Free for coaches.