Calculadora de Gordura Corporal pela Dobra Cutânea
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
Jackson-Pollock 3 dobras (densidade → Siri %BF = 495/dens − 450)
About this calculator
The Body Fat Calculator using skinfold measurements estimates body fat percentage based on three skinfolds following the Jackson-Pollock protocol. For men, the sites are chest, abdomen, and thigh; for women, triceps, suprailiac, and thigh. The method uses regression equations to calculate body density and then applies the Siri formula to convert density to fat percentage.
How it works: you enter the skinfold measurements in millimeters, select your sex, and provide your age. The calculator processes the data using sex-specific Jackson-Pollock equations. After obtaining body density, it applies the Siri formula: %Fat = (495 / Density) - 450. The result is an estimate of your body fat percentage.
This method is widely used by fitness professionals and nutritionists for body composition assessment. It is useful for tracking changes over training or diet programs. However, it requires proper training of the measurer to ensure accuracy. The technique is non-invasive and low-cost, but depends on the quality of the skinfold measurements.
Important precautions: measurements should be taken on the right side of the body, using a calibrated skinfold caliper. Skinfolds should be grasped vertically (except chest and suprailiac, which are diagonal). Avoid measuring after exercise or on wet skin. The Jackson-Pollock equation is validated for adults aged 18 to 55; outside this range, accuracy may be lower. The result is an estimate, not an absolute value.
Frequently asked questions
Do I need to be fasting for the measurement?
Fasting is not required, but avoid measuring right after heavy meals or exercise, as hydration and blood flow can affect skinfolds.
What is the margin of error for this method?
The margin of error is about 3 to 4% plus or minus, depending on the measurer's skill and caliper quality.
Can I use any skinfold caliper?
It is best to use a constant-pressure caliper (like Lange or Harpenden) that exerts 10 g/mm². Simple calipers may give inconsistent results.
Does the formula work for children or elderly?
The Jackson-Pollock equation was developed for adults aged 18 to 55. For children or elderly, other equations are more recommended.
What if my skinfold measurement is very large?
If the skinfold exceeds 40 mm, the equation's accuracy decreases. In that case, consider alternative methods like bioimpedance or DEXA.