This body fat 4 site skinfold measurement calculator determines the body fat percentage based on the triceps, thigh, suprailiac and abdomen skinfolds. There is in depth information, below the form, on the formulas used and on how to measure skinfolds with calipers.
How does this body fat 4 site skinfold measurement calculator work?
This health tool can help you determine the body fat percentage based on 4 skinfold measurements taken with calipers. Beside this, it offers information on the body’s fat and lean masses.
There are several fields to input in the body fat 4 site skinfold measurement calculator, each contributing to a particular area of the result:
■ Gender – is needed because there are different formulas for males and females.
■ Age – the formulas also account for the age of the subject.
■ Weight – subject weight can be input in pounds or kilograms and is used to determine body fat and lean masses.
■ Triceps – Vertical fold on the posterior midline of the upper arm, halfway between the bony processes (shoulder and elbow). The arm should be held freely to the side of the body.
■ Thigh – Vertical fold on the anterior midline of the thigh, half way between the proximal border of the patella and the hip.
■ Suprailiac – Diagonal fold, immediately superior and in line with the angle of the iliac crest, on the anterior axillary line.
■ Abdomen – Vertical fold, 2 cm to the right side of umbilicus.
Skinfold testing provides a simple way to monitor changes in body composition that may occur in time. It can be performed at home and upon the purchase of skinfold calipers (most are designed to be used by a second person, very few are for self-use), less costly than periodically having the measurement taken by a specialist.
The Durnin and Womersley is another 4 skinfold method while Jackson and Pollock have devised another two formulas, one for 3 site testing and another for 7 skinfolds.
Body fat percentages can be extracted from body circumferences, such as those from the US Navy tape measure method (neck, waist, hip). The most accurate but also complex method of assessing body fat is that of ultrasound testing.
In order to ensure consistency, it is recommended that the measurements are all taken on the same side of the subject. In some cases, it is normal that measurements are repeated.
Some sources argue that skinfold measurements should be used just to monitor progress and are not very reliable when it comes to comparing with fat percentages from tables. Other advice in regard to testing focuses on taking the measurements as accurately as possible, at the same time of the day and never after exercise.
Jackson and Pollock 4 site formula
The body fat percentage uses the sum of the skinfolds in two different formulas, adapted for gender:
BF% Females = (Triceps + Thigh + Suprailiac + Abdomen) x 0.29669 - (Triceps + Thigh + Suprailiac + Abdomen)2 x 0.00043 + Age x 0.02963 + 1.4072
BF% Males = (Triceps + Thigh + Suprailiac + Abdomen) x 0.29228 - (Triceps + Thigh + Suprailiac + Abdomen)2 x 0.0005 + Age x 0.15845 – 5.76377
Body fat mass is extracted from the above percentage with the use of weight:
Body fat mass = BF% x Weight / 100
Lean body mass is calculated as the difference between weight and body fat mass because it represents the portion of weight that is lean (not made of fat).
Example of a calculation
Taking the case of a male aged 27, weighing 178 lbs and having the following skinfold measurements:
Triceps= 21; Thigh = 16; Suprailiac = 11; Abdomen = 26;
The calculation result is:
■ Body fat percentage = 17.4%;
■ Body fat mass = 31.0 lbs;
■ Lean body mass = 147.0 lbs.
Fat percentages can offer information on the fitness levels of the body:
| Fat level | Females (% BF) | Males (% BF) | ||||||
| 20 - 30 y | 30 - 40 y | 40 - 50 y | 50+ y | 20 - 30 y | 30 - 40 y | 40 - 50 y | 50+ y | |
| Very low | <17% | <18% | <20% | <21% | <9% | <11% | <12% | <13% |
| Low | 17 - 20% | 18 - 21% | 20 - 23% | 21 - 24% | 9 - 12% | 11 - 13% | 12 - 15% | 13 - 16% |
| Average | 21 - 23% | 22 - 24% | 24 - 27% | 24 - 31% | 13 - 16% | 14 - 17% | 16 - 20% | 17 - 21% |
| Very high | 24 - 27% | 25 - 29% | 28 - 31% | 32 - 35% | 17 - 19% | 18 - 22% | 21 - 25% | 22 - 27% |
| Over-fat | 28% + | 30% + | 32% + | 36% + | 20% + | 23% + | 26% + | 28% + |
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) Jackson AS, Ellis KJ, McFarlin BK, Sailors MH, Bray MS. (2009) Cross-validation of generalised body composition equations with diverse young men and women: the Training Intervention and Genetics of Exercise Response (TIGER) Study. Br J Nutr; 101(6): 871–878.
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.
5) 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.
08 Nov, 2016