Health⏱ 5 min read
How to Calculate Body Fat Using Skin Fold Measurements
Skin fold calipers remain one of the most accessible and accurate methods for tracking body composition changes. Here are the Jackson-Pollock formulas and how to take measurements correctly.
DEXA scans are the gold standard for body composition, but skin fold calipers provide surprisingly accurate tracking of changes over time — especially useful for athletes and those cutting or bulking.
What Skin Fold Measurements Assess
Skin folds measure subcutaneous fat (fat under the skin).
Not the same as total body fat (misses visceral fat).
However, subcutaneous fat correlates well with total body fat
in most non-extreme body compositions.
Accuracy vs DEXA:
Within 3-4% body fat for most people
Within 1-2% for the same measurer on the same person over time
(Tracking changes is more reliable than absolute measurement)
Jackson-Pollock 3-Site Formula
Men (chest, abdomen, thigh — all in mm):
Body density = 1.10938 - (0.0008267 x sum) + (0.0000016 x sum^2) - (0.0002574 x age)
Women (tricep, suprailiac, thigh — all in mm):
Body density = 1.0994921 - (0.0009929 x sum) + (0.0000023 x sum^2) - (0.0001392 x age)
Convert density to body fat %:
Body fat % = (495 / Body density) - 450 [Siri equation]
Example: 32-year-old man
Chest: 12mm, Abdomen: 22mm, Thigh: 16mm
Sum = 50mm
Body density = 1.10938 - (0.0008267 x 50) + (0.0000016 x 2500) - (0.0002574 x 32)
= 1.10938 - 0.04134 + 0.004 - 0.00823 = 1.06381
Body fat % = (495 / 1.06381) - 450 = 465.3 - 450 = 15.3%
How to Take Skin Fold Measurements
- All sites: Measure on the right side of the body. Pinch with thumb and forefinger, pull skin away from muscle. Apply calipers 1cm below fingers.
- Chest (men): Diagonal fold, midway between anterior axillary line and nipple
- Abdomen (men): Vertical fold, 2cm to the right of the navel
- Thigh (both): Vertical fold, midpoint of anterior thigh (between hip and knee)
- Tricep (women): Vertical fold, midpoint of back of upper arm
- Suprailiac (women): Diagonal fold, just above the hip bone, anterior axillary line
Take 3 readings at each site and use the median (middle value).
Measure before exercise — not after (exercise increases blood flow
to skin, which can inflate readings).
Same time of day, same measurer, for consistency in tracking.
7-Site Formula (More Accurate)
Jackson-Pollock 7-site (men):
Sites: chest, mid-axillary, tricep, subscapular, abdomen, suprailiac, thigh
Body density = 1.112 - (0.00043499 x sum) + (0.00000055 x sum^2) - (0.00028826 x age)
Women (same 7 sites):
Body density = 1.097 - (0.00046971 x sum) + (0.00000056 x sum^2) - (0.00012828 x age)
The 7-site formula is more accurate but requires more practice.
For home use, the 3-site formula tracked consistently gives
reliable progress data.