Skinfold Body Fat Calculator
Free Skinfold body fat Calculator with medically-sourced formulas. Enter your measurements for personalized, accurate health insights.
Reviewed for accuracy by Rahul Singh, Health & Wellness Specialist
Medical disclaimer: This calculator is provided for educational and informational purposes only and does not constitute medical advice, diagnosis, or treatment. Results are general estimates and may not reflect your individual circumstances. Always consult a qualified healthcare professional before making decisions about your health.
Skinfold Body Fat Calculator
Calculator
Adjust values & calculateEnter your values below. Every result is computed in your browser — no data is sent to any server.
Formula: BD(male) = 1.10938 - 0.0008267(S) + 0.0000016(S^2) - 0.0002574(age) | BF% = (4.95/BD - 4.5) x 100
Worked example — Body Fat: 13.2% (Athletic) | Fat Mass: 10.8 kg | Lean Mass: 71.2 kg
Formula
BD(male) = 1.10938 - 0.0008267(S) + 0.0000016(S^2) - 0.0002574(age) | BF% = (4.95/BD - 4.5) x 100
Where S is the sum of 3 skinfold sites (chest+abdominal+thigh for males, tricep+suprailiac+thigh for females). Body density (BD) is converted to body fat percentage using the Siri equation. The Jackson-Pollock formulas account for age-related fat redistribution.
Worked Examples
Example 1: Male 3-Site Skinfold Assessment
Problem:A 28-year-old male has chest=10mm, abdominal=20mm, thigh=14mm skinfolds. Weight is 82 kg.
Solution:Sum of 3 folds (male) = 10 + 20 + 14 = 44 mm Body Density = 1.10938 - 0.0008267(44) + 0.0000016(44^2) - 0.0002574(28) BD = 1.10938 - 0.03637 + 0.003098 - 0.007207 = 1.06880 Body Fat (Siri) = (4.95/1.06880 - 4.5) x 100 = (4.632 - 4.5) x 100 = 13.17% Fat mass = 82 x 0.1317 = 10.8 kg Lean mass = 82 - 10.8 = 71.2 kg
Result:Body Fat: 13.2% (Athletic) | Fat Mass: 10.8 kg | Lean Mass: 71.2 kg
Example 2: Female 3-Site Skinfold Assessment
Problem:A 35-year-old female has tricep=18mm, suprailiac=15mm, thigh=22mm skinfolds. Weight is 65 kg.
Solution:Sum of 3 folds (female) = 18 + 15 + 22 = 55 mm Body Density = 1.0994921 - 0.0009929(55) + 0.0000023(55^2) - 0.0001392(35) BD = 1.0994921 - 0.054610 + 0.006959 - 0.004872 = 1.04697 Body Fat (Siri) = (4.95/1.04697 - 4.5) x 100 = (4.728 - 4.5) x 100 = 22.77% Fat mass = 65 x 0.2277 = 14.8 kg Lean mass = 65 - 14.8 = 50.2 kg
Result:Body Fat: 22.8% (Fitness) | Fat Mass: 14.8 kg | Lean Mass: 50.2 kg
Frequently Asked Questions
What is skinfold body fat testing and how does it work?
Skinfold body fat testing is a widely used anthropometric method that estimates total body fat percentage by measuring the thickness of subcutaneous fat at specific anatomical sites using calibrated calipers. The underlying principle is that approximately 50 percent of total body fat is stored directly beneath the skin as subcutaneous fat, and the thickness of this layer at standardized sites correlates predictably with total body fat percentage. A trained technician pinches the skin and underlying fat away from the muscle at each measurement site, applies the calipers at a standardized pressure, and records the thickness in millimeters. These measurements are then entered into validated regression equations (such as the Jackson-Pollock formulas used in Skinfold Body Fat Calculator) that convert the sum of skinfolds into body density, which is then converted to body fat percentage.
What are the Jackson-Pollock equations used in Skinfold Body Fat Calculator?
Skinfold Body Fat Calculator uses the Jackson-Pollock 3-site skinfold equations, which are among the most widely validated and commonly used body composition prediction formulas in exercise science. For males, the three measurement sites are chest, abdominal, and thigh, using the equation: Body Density = 1.10938 - 0.0008267(sum) + 0.0000016(sum squared) - 0.0002574(age). For females, the three sites are tricep, suprailiac, and thigh, using: Body Density = 1.0994921 - 0.0009929(sum) + 0.0000023(sum squared) - 0.0001392(age). These quadratic equations include age as a variable to account for the redistribution of fat from subcutaneous to visceral deposits that occurs with aging. The resulting body density is then converted to body fat percentage using the Siri equation.
How do I properly take skinfold measurements for accurate results?
Proper skinfold measurement technique is crucial for reliable results and involves several standardized steps. Always measure on the right side of the body, as the equations were developed using right-side measurements. Identify the anatomical landmark precisely: chest skinfold is taken diagonally halfway between the anterior axillary line and the nipple, abdominal is vertical 2 cm lateral to the navel, thigh is vertical on the midline of the anterior thigh halfway between the hip and knee joints, tricep is vertical on the posterior midline of the upper arm halfway between the acromion and olecranon processes, and suprailiac is taken diagonally above the iliac crest at the anterior axillary line. Pinch the skin firmly, apply calipers 1 cm below the fingers, wait 2 seconds for the reading to stabilize, and take at least two measurements at each site.
What is the difference between the Siri and Brozek body fat equations?
Both the Siri and Brozek equations convert body density to body fat percentage, but they use slightly different assumptions about the density of fat and fat-free tissue. The Siri equation (1961) uses the formula Body Fat % = (4.95 / Body Density - 4.5) x 100, assuming fat density of 0.9007 g/cc and fat-free mass density of 1.1000 g/cc. The Brozek equation (1963) uses Body Fat % = (4.57 / Body Density - 4.142) x 100, with slightly different density assumptions. For most individuals, the two formulas produce results within 1 to 2 percentage points of each other. The Siri equation tends to slightly overestimate body fat at very high fat percentages and slightly underestimate at very low percentages. The Brozek equation may be more accurate for lean or obese individuals at the extremes of the body composition spectrum.
How accurate are skinfold measurements compared to DEXA and other methods?
When performed by a skilled and experienced technician, skinfold measurements can estimate body fat percentage within 3 to 4 percentage points of values obtained through DEXA scanning, which is considered the clinical gold standard. This level of accuracy is comparable to bioelectrical impedance analysis and substantially better than visual estimation or BMI-based predictions. However, accuracy depends heavily on the technician skill level, with inter-tester variability often being the largest source of error. The same person measuring consistently (intra-tester reliability) typically achieves results within 1 to 2 mm between measurements. For tracking changes over time, skinfold testing can be highly effective when the same technician performs measurements under standardized conditions, as even if absolute values contain some error, the direction and magnitude of change will be accurately captured.
What factors can cause inaccurate skinfold measurements?
Several factors can compromise skinfold measurement accuracy and should be controlled or accounted for when possible. Hydration status significantly affects skin turgor and compressibility, so measurements should ideally be taken in a normally hydrated state, avoiding testing immediately after heavy sweating or excessive fluid intake. Exercise within 4 to 6 hours before measurement can increase blood flow to subcutaneous tissues, potentially inflating readings by 2 to 3 mm at some sites. Skin lotions, oils, or creams make the skin slippery and more difficult to grasp consistently. The type and calibration of calipers matters considerably, with clinical-grade Harpenden and Lange calipers providing more accurate and consistent readings than inexpensive plastic models. Measuring very obese individuals presents technical challenges because extremely thick folds may exceed caliper capacity, and the equation accuracy decreases at very high fat levels.
Why do the measurement sites differ between males and females?
The different measurement sites for males (chest, abdominal, thigh) and females (tricep, suprailiac, thigh) in the Jackson-Pollock 3-site protocol reflect fundamental biological differences in fat distribution patterns between the sexes. Males tend to accumulate fat preferentially in the trunk region, particularly the chest and abdomen, making these sites most predictive of total body fatness in men. Females typically store more fat in the upper arms (tricep region) and around the hips (suprailiac area) due to the influence of estrogen on fat cell distribution and function. These sex-specific equations were developed through regression analysis of large population samples, with the selected sites being those that produced the strongest statistical prediction of body density measured by hydrostatic weighing. Using the correct gender-specific equation is essential for accuracy.
Can I perform skinfold measurements on myself or do I need a professional?
Self-measurement of skinfolds is possible but significantly more challenging than having a trained professional perform the measurements, and accuracy will generally be lower. Certain sites like the subscapular (upper back) are impossible to self-measure, and even accessible sites like the abdominal and thigh are difficult to pinch and apply calipers simultaneously. If self-testing, the tricep and suprailiac sites are the most manageable for self-measurement. Use a quality pair of calipers with a comfortable grip, practice the pinching technique extensively, and always take multiple readings. For tracking personal progress, self-measurement can still be valuable if you maintain consistent technique between sessions, even if absolute values are somewhat less accurate. For clinical or research purposes, measurements should always be performed by a certified professional with demonstrated inter-tester reliability.
How does age affect skinfold-based body fat estimation?
Age is included as a variable in the Jackson-Pollock equations because aging produces systematic changes in body fat distribution that affect the relationship between skinfold thickness and total body fat. As people age, subcutaneous fat tends to decrease relative to total body fat, while visceral (internal) fat increases, meaning that a given skinfold sum may underestimate total body fat in older adults compared to younger adults with the same measurements. The age coefficient in the equations attempts to compensate for this shift, adding approximately 0.26 percentage points to the male body fat estimate for each year of age and approximately 0.14 points for females. However, this linear age correction is an approximation, and the equations are most accurate for adults aged 18 to 60. For individuals over 60, the equations may still underestimate true body fat percentage.
What body fat percentage should I aim for based on my fitness goals?
Optimal body fat targets depend on your specific goals, sport requirements, and individual health considerations. For general health, men should aim for 10 to 20 percent and women for 18 to 28 percent, ranges associated with minimal chronic disease risk and good metabolic function. Competitive athletes typically maintain lower levels: male endurance athletes at 6 to 13 percent, male team sport athletes at 8 to 16 percent, female endurance athletes at 12 to 20 percent, and female team sport athletes at 16 to 25 percent. Bodybuilding competition condition (3 to 6 percent for men, 8 to 15 percent for women) is not sustainable or healthy long-term and should only be achieved temporarily under professional supervision. Dropping below essential fat levels (approximately 3 percent for men, 12 percent for women) poses serious health risks including hormonal disruption, immune suppression, and bone density loss.
References
Reviewed for accuracy by Rahul Singh, Health & Wellness Specialist · Editorial policy
Related Calculators
🎖️Army Body Fat
Military body fat tape test calculator
🧮Navy Body Fat Calculator — Circumference Method
Calculate navy body fat with inputs, formulas, and instant results.
🧮BMI Calculator - Body Mass Index
Calculate bmicalculator body mass index with inputs, formulas, and instant results.
🧮Body Frame Size Calculator
Calculate body frame size with inputs, formulas, and instant results.
🧮Body Shape Calculator
Calculate body shape with inputs, formulas, and instant results.
🧮BRI Calculator - Body Roundness Index
Calculate bricalculator body roundness index with inputs, formulas, and instant results.
🧮BSA Calculator - Body Surface Area
Calculate bsacalculator body surface area with inputs, formulas, and instant results.
🧮RFM Calculator - Relative Fat Mass
Calculate rfmcalculator relative fat mass with inputs, formulas, and instant results.