4 Skinfold Body Fat Calculator

Skinfold measurements are one of the most widely-used techniques for assessing body fat percentage; a factor in determining health and fitness.

While the scale tells the weight, it isn’t a good measure of body fat although there are some good body fat-specific scales. 

Get an estimate of your body fat percentage, body composition (fat to lean mass ratio), and fat category using this easy-to-use fitness tool. 

What are Skinfold Measurements?

While there are many different methods that you can use to approximate body fat percentage, taking skinfold measurements is arguably one of the most common and practical for most people. It’s also a very convenient method while costing less than a lot of other fat-measuring tests. 

Skinfold body fat assessments typically involve using a caliper tool to measure folds of subcutaneous adipose tissue in common fat-storing areas such as the abdomen, thigh, triceps, and suprailiac.

There are different tiers of calipers from cheap and simple to more expensive and feature-rich. You can use either as it just comes down to your preference and budget. 

You will need a caliper for this calculator. The 4 skinfold equations were built on caliper readings in millimeters, so a pinch measured with a soft tape will not fit them.  

With either kind of caliper, anyone should be able to do a 4 skinfold assessment to estimate their body fat, body composition, and fat category. 

How to Use The 4 Skinfold Calculator 

The 4 skinfold calculator is very easy to use and we’ve included step-by-step instructions. 

Step 1: Choose the desired unit of measurement: US (lb, in) or Metric (kg, cm)

Step 2: Select your gender

Step 3: Enter your weight 

Step 4: Type in your height and age (height does not change the 4 skinfold result)

Step 5: Take your skinfold measurements and enter the values in millimeters for triceps, thigh, suprailiac, and abdomen. 

Step 6: Press Calculate!

How To Take Measurements

This is the more involved part of determining your body fat percentage so it’s imperative that you do it correctly for the most accurate results. 

You can take the measurements yourself, but we recommend having someone help you especially for the triceps and suprailiac areas that are not as easy to reach and subsequently, get an accurate measurement.  

There are a few factors that can affect the measurement aside from fat mass such as age, hydration, and skin firmness. Some people have firmer skin that is impossible to pinch, while it’s much easier for others. 

For those who have very firm skin, other methods will be a better option. 

When you pinch each fold between your thumb and index finger before placing the caliper on it, you want to make sure you’re only grasping the fat and not the muscle too. You can feel the muscle underneath and if that is the case, bring your fingers closer together until you’re only pinching and pulling the fat. Adjust your grip as needed.

We also recommend taking a minimum of two measurements per fold site to ensure accuracy. Wait a few seconds between measurements. If there’s a discrepancy of more than 1mm between two measurements, take another and use the average of the three.

We recommend testing the right side of the body for consistency. 

Here’s a very helpful video that demonstrates how to correctly take chest, abdomen, and thigh measurements using a caliper.

Check here for the triceps and suprailiac measurement which are common female fold sites, although, for this calculator, there are no gender-specific fold sites.

Abdomen

Take a vertical skinfold measurement by pinching either side of the navel (belly button). 

Thigh

Raise the upper leg as high as possible and take a vertical skinfold measurement between the hip and knee joints. 

Triceps 

While the arm is relaxed by the side, locate the midline of the posterior upper arm between the acromion (top of the shoulder bone) and the elbow. Pinch a vertical skinfold and record your measurement. 

Suprailiac

Don’t let the name intimidate you, the suprailiac is a common skinfold measuring site. To effectively take this measurement, you want to pinch a diagonal skinfold about 1 cm above the anterior superior iliac crest (top of hip bone). 

Analyzing Your Results!

The calculator will display an approximation of your body fat percentage, fat mass in pounds/kg, lean mass in pounds/kg, and “fat category”.

We’ve included example results for a 30-year-old male who weighs 125 lbs/56.7 kg and has the following skinfold measurements: triceps (10mm), thigh (15mm), suprailiac (20 mm), and abdomen (15 mm).

• Body fat: 14.8%
• Fat mass: 18.5 lb
• Lean mass: 106.5 lb
• Fat category: Fitness

So based on the results, this individual has 14.8% body fat, 18.5 pounds of fat mass, 106.5 pounds of lean mass (muscles, bone, organs, etc), and falls in ACE’s Fitness range. 

See if you meet the US Navy body fat standards here.

Comparing Different Methods

Taking skinfold measurements is a good way to calculate your body fat and body composition. If we’re being truthful though, it’s hardly the most accurate method although doing it right will get you somewhat close.

However, it is one of the most convenient and still oftentimes more accurate than the most basic techniques (e.g, cheap body fat scales, basic calculators, etc).

Done correctly, skinfold equations in general have a typical error of about 3.5 percentage points, the American Council on Exercise’s figure, and any one reading can miss by more. The 4 skinfold equation has no published error we could find, which is why the calculator shows none. 

The “superior” body fat measuring techniques may not give you 100% accurate measurements either but they should guess your body fat within just a few percent of what it actually is and they’re pretty reliable, although not necessarily consistent between variations. 

Body fat scales and other portable and handheld devices are often seen as the least accurate methods of determining body fat and composition. 

The most accurate methods from our research are hydrostatic weighing and DEXA/DXA scan of which the latter also measures fat type. But they’re more expensive to have done and require you to visit a facility that offers these more advanced technologies. 

But if we’re being completely honest whatever method you use just be consistent with it. If you can match your mirror results to improved body fat percentage numbers then your method is likely working. 

You’ll also find more success by familiarizing yourself with what certain body fat percentages look like and this can also help you to find the right method and numbers for you!

What Can These Measurements Tell You and Comparison to BMI

Measuring body fat and estimating lean to fat mass ratio have been shown to be important indicators of health and fitness.

Body mass index (BMI) is also a common formula that health professionals use for this very reason. 

But BMI only considers body weight relative to height, not body composition. It simply offers a BMI score and ideal weight range. A formula can turn BMI, age and sex into a body fat estimate, as the BMI method in this calculator does, but it still cannot tell muscle from fat.

“If we think of BMI being a rough measure of body fatness, there are people, especially some highly trained athletes, who are overweight but not overfat,” says Steven Heymsfield, MD, director of the Obesity Research Center at St. Luke’s Roosevelt Hospital in New York. “Likewise, there are people who are of a normal weight according to BMI scales but who are overfat. BMI is a broad, general measure of risk. Body-fat assessment is much more specific to your actual fat content and thus provides a more accurate picture.”

That doesn’t mean BMI is a useless tool though because it does have a place as weight relative to height could tell about someone’s health risks.

Although, body composition is a better measure of health and fitness for more active people who also do resistance training. Some people also have heavier frames and carry more muscle naturally. A recommended weight range may be a good tool to determine if you’re at a healthy or unhealthy weight. 

A high body fat percentage is associated with being overweight, obese, out of shape and/or at risk for health issues. But having too little body fat can have adverse effects as well.

The good news is that anyone can improve their health and fitness by making a few lifestyle changes such as doing resistance training and having a healthier diet.

Try these body composition exercises to build more muscle and shed fat. 

Body Fat in Men vs. Women 

It’s important to note that men and women are not the same when it comes to healthy body fat percentage.

On average, women tend to carry more body fat than men because of reproduction. 

“It’s comforting to know that women can be and should be fatter than men. They have a totally different reproduction function and the higher fat in women supports that reproductive function,” explained Barbara J. Moore, PhD, president of Shape Up! America. 

The American Council on Exercise (ACE) has body fat charts based on various categories. 

So for example, a recommended and healthy body fat range for male athletes is 6-13% while it’s 14-20% for women. 

But men and women also tend to differ in how they carry body fat (1).

You’ve probably noticed that women tend to store more fat in the glutes, thighs, and legs while men usually accumulate fat in the midsection, chest, shoulders, neck, and upper body in general.

There are advantages and disadvantages for both though, mainly because not all fat is the same. 

Seeing as men are more prone to developing larger midsections (at least initially in comparison), this may indicate too much visceral fat (deeper fat typically stored in the belly and around the organs) storage. Although belly fat is both visceral and subcutaneous (fat stored under the skin and measured when estimating body fat percentage).

That’s not to say that subcutaneous fat is better as too much can affect health and hormones too. 

But excess visceral fat accumulation is more associated with a higher risk of heart attacks, stroke, cancer, diabetes, dementia, and more. 

It seems many health publications suggest that a waist circumference larger than 35 inches for women and 40 inches for men increases disease risk. 

The key takeaway here is that while a large belly may put you more at risk for disease than a thick butt and thighs, monitoring body composition is extremely important for health. 

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3 Fold vs. 4 Fold Measurement

We also offer a 3 fold body fat calculator that measures just 3 sites including the chest, abdomen, and thigh for males or triceps, suprailiac, and thigh for women. 

It’s a simpler method that takes less time and effort. We can’t say measuring more sites makes the 4 fold tool more accurate. We found no published typical error for the 4 skinfold equation, so there is nothing to compare the 3 skinfold equations against. 

However, you could take measurements and compare 3 and 4 skinfold tests and then compare them to other body fat methods as well. 

Assess Your Body Fat to Lean Tissue Ratio Using The 4 Skinfold Method

The 4 skinfold body fat calculator offers a simple method to estimate your body fat, body composition, and fat category. 

With a caliper, used by you or a helper, it’s possible for anyone to approximate their body fat levels.

While it may not be the most accurate method compared to others, the simplicity of skinfold measurements makes them a viable option.