3-Point Skin Fold Bodyfat Calculator

The following calculator gives you an estimate of your % bodyfat and lean body mass based on your weight, age and thickness measurements of 3 skin folds. It is based on the Jackson-Pollock 3-point method and is reasonably accurate for most people. This method, however, as almost all popular skin fold methods, tends to underestimate body fat levels in very lean bodybuilders.

Note: This statistics calculator is presented for your oTo perform each measurement: Using the tips of your thumb and forefinger pinch the skin in the area to be measured. Pull the skin away from the muscle, being sure to ‘get’ all the subcutaneous fat underneath the skin but don’t include the underlying muscle. Measure the thickness of this fold of fat and skin, in millimeters, with either a ruler (metric) or skin fold calipers. If you do have calipers, the jaws should be placed close to where the fingertips have the skin pinched so an accurate reading can be obtained (about 1 cm (1/4 in) away from the fingers). Release the caliper’s handles and wait 2 seconds before taking the reading. Take a reading of that same site a few more times (release the fold and get a new ‘pinch’ for each measurement) and take the average – each reading should be within 1 or 2 mm of each other. If you don’t have calipers you’ll have to make do with a ruler.

The procedure differs between genders. Males take measurements at the pectoral, abdominal and thigh regions and females take measurements at the triceps, suprailiac and thigh regions. The locations for both sexes are illustrated below.

What are skinfold measurements?

While there are many ways to determine body fat percentage, skinfold measurement is one of the most common. It is also one of the most convenient methods that anyone can perform at home.

This method uses a caliper to measure skinfold thickness (subcutaneous fat tissue) in common fat-storing areas such as the abdomen, chest and thighs (for men) or triceps, thighs and hamstrings (for women).

While some of the higher-end calipers with displays can cost hundreds of dollars, you can also use simpler calipers that are much less expensive.

If you don't have a caliper, the next best option is to pinch the skin folds with your fingers, measure the thickness with a soft tape, and enter the numbers manually (that's where this calculator comes in).  

Also, a minimum of two measurements should be taken at each location. If the two measurements differ by more than 2 millimeters, a third measurement should be taken to determine their body fat, body composition, and fat category. The body composition calculator then uses the average of the 2-3 measurements when making the calculations.

Input Fields

US/Metric: Choose "English" (for US) or "Metric" units.

Gender: Select your gender.

Age: Your current age.

Weight: Your current scale weight.

Triceps: Use calipers to measure a vertical fold directly on the back of the upper arm and halfway between the shoulder and elbow.            

Thigh: Use calipers to measure a vertical fold directly on the front of the upper leg and halfway between the knee and the crease created when you lift your leg.            

Suprailiac: Use calipers to measure a diagonal fold directly above the hipbone. The angle of the fold should be about the same angle as the hipbone.            

Output Fields

Body Fat: The approximate percentage of your body’s mass that is made up of fat.

Fat Mass: The portion of your weight that is fat.

Lean Mass: The portion of your weight that is lean (not fat).

Body Fat Category: Your body fat category depends on your gender and your body fat percentage.

Body Fat Categories Table: This table shows you the Body Fat Range for each Classification so you can see how close your calculated Body Fat percentage is to the next Body Fat Classification range.

Jackson and Pollock 3 site formula

The skinfold measurements obtained with the calipers need to be input in the gender specific formulas and the intermediary result is the body density, noted D.

For females:

D = (1.0994921 - (0.0009929 x (Triceps + Thigh + Suprailiac)) + (0.0000023 x (Triceps + Thigh + Suprailiac)²) - (0.0001392 x Age))

For males:

D = (1.10938 - (0.0008267 x (Thigh + Chest + Abdomen)) + (0.0000016 x (Thigh + Chest + Abdomen)²) - (0.000257 x Age))

Body density is transformed in fat percentage with the SIRI formula:

BF% = 495/ D - 450

Body fat is obtained from the BF% and subject weight based on:

Body fat mass = BF% x Weight / 100

Lean body mass = Weight – Body fat mass

Example calculation

Taking the case of a female aged 28, weighing 146 lbs and having the following skinfold measurements:

Thigh = 24; Triceps = 18; Suprailiac = 26;

The calculation result is:
Body fat percentage = 26.6%;
Body fat mass = 38.8 lbs;
Lean body mass = 107.2 lbs;
Body density = 1.04 x 103 kg/m³.

Because fat percentages can offer information on the fitness levels of the body, the American Council on Exercise devised the following:

References

1. Jackson AS, Pollock ML, Ward A. (1980) Generalized equations for predicting body density of women. Med Sci Sports Exerc; 12(3):175-81.
2. Jackson AS, Pollock ML. (1978) Generalized equations for predicting body density of men. Br J Nutr; 40(3):497-504.
3. Vasudev S, Mohan A, Mohan D, Farooq S, Raj D, Mohan V. (2004) Validation of body fat measurement by skinfolds and two bioelectric impedance methods with DEXA--the Chennai Urban Rural Epidemiology Study [CURES-3]. J Assoc Physicians India; 52:877-81.
4. Aristizábal JC, Restrepo MT, Amalia L. (2008) Validation by hydrodensitometry of skinfold thickness equations used for female body composition assessment. Biomedica; 28(3):404-13.