By Marnie Kunz, NASM-certified trainer, USATF- RRCA-certified run coach

If you’re wondering how to calculate body fat, this guide offers 10 methods you can try and my top tips as a trainer to help you lose body fat. Whether you’re an athlete focused on your sports performance or want to lose weight to achieve a healthy amount of body fat, these methods can help you calculate your body fat. Some techniques are more accurate than others, so we’ll go over the pros and cons of each one.

What Is Body Fat?

Your body composition includes the percentage of fat, bone, and muscle. Body fat is the amount of fat tissue in your body. Your body fat percentage does not include any muscle tissue or body fluids. If you want to measure your fitness progress by more than just your total body weight, learning how to calculate body fat is especially helpful.

When training people who want to lose weight, I always encourage using a few ways to measure progress so that one number doesn’t make or break anyone. Body fat percentage can be a great way to track your fitness progress and overall health. I also recommend setting performance and progress goals for a well-rounded, sustainable fitness program.

Optimal Body Fat Ranges

When it comes to body fat, women naturally have a higher percentage of body fat than men. Also, people tend to accumulate more fat with age. The American Journal of Clinical Nutrition offers guidelines on healthy body fat percentages, with women ranging between 21 to 35 percent body fat, depending on age. According to the guidelines, men should fall within the 8 to 24 percent range.

You can check out the guidelines based on age and sex in our chart.

How to Calculate Body Fat

There are different methods you can learn for how to calculate body fat. Here are some of the most common ways to determine body fat:

1. Calipers

Calipers are a popular, low-cost way to measure body fat. These handheld devices use a pinching motion to measure skinfolds at different points on your body. Usually, you will take up to three measurements at each point that you test on your body and then use a chart or formula to calculate your total body fat percentage based on your measurements.

Pros: Low-cost, easy to use, and accessible online or in stores.
Cons: Accuracy depends on the tester's experience, with more experienced testers getting the most accurate measurements. It is less precise than more advanced tests but is one of the most accurate home tests for how to calculate body fat.
Availability: Easy to buy online or in stores.
Accuracy: Not the most accurate. It works best when administered by an experienced person who knows anatomy. In one study of caliper accuracy, the accuracy ranged from a total error rate of 7.9 to 10.9% body fat.

2. Smart Scale

Smart scales are a convenient, easy way to calculate body fat. These high-tech scales send a low-level electrical current through your body and measure the returned voltage. The voltage then calculates your body composition, including your body fat percentage.

Pros: Easy to use, can use it at home. No complex math or measurement techniques.
Cons: Accuracy can vary and will generally not be as accurate as professional tools in doctor offices or research facilities. Prices can range from budget-friendly to a couple hundred dollars or more.
Availability: Easily available online.
Accuracy: Dehydration levels and the time of day can affect your results, and individual scales can differ in accuracy. Take your measurements at the same time when you weigh yourself for the best results.

3. Body Mass Index

Body mass index (BMI) is a common way to estimate body fat percentage. Although this method can offer you a way to gauge your health, some limitations exist. Your BMI may not accurately measure your body fat if you have a high muscle mass (such as me and other weightlifters). However, BMI is an easy and free way to learn how to calculate body fat, so it may be one metric you use to measure your progress.

BMI is an estimate of your body fat based on your height and weight. If you know your height and weight, you can use the National Heart, Lung, and Blood Institute’s BMI calculator to determine your body mass index.

The formula to find your BMI is to divide your weight in kilograms by your height in meters squared. For Americans, divide your weight in pounds by your height in inches squared and multiply by 703.

Pros: Easy, free way to estimate your body fat percentage
Cons: Based on height and weight, not an actual measurement of body fat percentage
Availability: Easily accessible through online calculators or calculating yourself based on height and weight.
Accuracy: BMI can give a general health metric but is not an accurate way to measure body fat percentage, especially for people with a high muscle mass, pregnant women, and seniors.

4. Body Circumference Measurements

Body circumference measurements can help you learn how to calculate body fat. Your body shape and size give clues as to your percent of body fat, and this method is easy to do at home.

The U.S. Army uses a body fat calculator with a few measurements - your stomach circumference, age, and weight, to estimate body fat percentage. Stomach circumference is a popular way to assess fitness level because some of the most harmful body fat tissue can be found in belly fat.

Pros: Cost-effective, easy to do at home.
Cons: There are more accurate methods and it depends on how accurately you measure your body.
Availability: Measuring tapes are readily available online and in many stores.
Accuracy: The error rate can vary greatly depending on what circumference measurements and body fat calculator you use. Have someone measure your body if you need help getting the most accurate measurements.

5. Hydrostatic Weighing

Hydrostatic weighing is one of the most accurate ways to measure your body fat percentage. This method uses water to measure your body density and determine fat percentage. You will need to go to a research facility or university to access the machine for underwater weighing.

Pros: High degree of accuracy for most people.
Cons: It can be costly and complicated to access as you need to go to a facility with the equipment for hydrostatic weighing, such as a university.
Availability: Must go to a location with hydrostatic weighing equipment.
Accuracy: A generally high degree of accuracy. However, athletes have denser bones and may not get as accurate a reading as most people.

6. Air Displacement

Air displacement has become increasingly used to calculate body fat percentage with high accuracy rates and less mess than underwater weighing. This method measures how much air is displaced when a person is in the chamber to calculate body density and body fat.

Pros: Very accurate, fast, and good for people of all ages and sizes.
Cons: It can be hard to find a facility with the equipment, and cost can be high.
Availability: Usually, you will have to go to a research facility or university for this measurement.
Accuracy: High degree of accuracy but does not tell where fat is located.

7. Dual-energy X-ray Absorptiometry (DXA)

This X-ray system uses two types of X-rays to measure your body fat. For this procedure, you will lie down while your body is scanned. This highly accurate method can tell you your bone density, lean body mass, and fat mass. It is among the most accurate and precise ways to calculate body fat.

Pros: Extremely accurate and precise, relatively quick (usually 10 minutes or less)
Cons: It can be costly. You can not do this method at home.
Availability: Only in medical or research facilities.
Accuracy: High

8. Bioelectrical Impedance Analysis (BIA)

Bioelectrical impedance analysis (BIA) uses electrodes to measure your body’s response to electrical currents. Fat tissue slows down electrical currents. After taking measurements, a BIA uses a formula to calculate your body fat percentage.

BIA devices are available online or in medical settings. Accuracy varies, but the higher-priced, professional devices are generally more accurate than those available to the general public.

Pros: Quick and easy to use. Devices are available to buy online and in stores.
Cons: Accuracy can vary depending on the device and can be affected by what you eat and drink.
Availability: Can be purchased online or accessed in medical settings.
Accuracy: The accuracy varies depending on the device used.

9. Bioimpedance Spectroscopy (BIS)

Bioimpedance spectroscopy is another way to estimate body fat based on electrical impulses in your body. Although BIS is similar to the BIA method, this technique uses more electrical currents and a different measurement system.

Pros: Quick and easy to do, but you must go to a fitness center, medical facility, or research facility with the equipment.
Cons: It cannot be done at home as the equipment is only available to wellness and academic professionals. Accuracy can vary.
Availability: Devices are unavailable to the general public, so you must go to a health or medical facility.
Accuracy: BIS accuracy can vary, with BIS devices having a similar degree of accuracy as professional-grade BIA equipment.

10. Waist-to-Hip Ratio

All you need for this technique is a measuring tape. Measure your waist and hip circumferences and divide your waist measurement by your hip measurement. In general, a waist-hip ratio above .85 for women and above .90 for men is considered a high risk for health problems such as obesity and type 2 diabetes.

Pros: Easy to do, can be done at home. Low-cost.
Cons: You will need to get accurate measurements. Although you’ll get a general health metric, you won’t be able to calculate your exact body fat percentage.
Availability: Readily available, a measuring tape can be purchased online or in stores
Accuracy: This method gives you a general health metric but does not determine your exact body fat percentage.

Tips to Reduce Your Body Fat

Now that you know how to calculate body fat, you may want to reduce your body fat percentage. These tips can help you lose fat and improve your fitness level:

Strength train. Do at least two weekly strength training sessions to build lean muscle mass and reduce fat. You can do bodyweight exercises, weightlifting, or exercises with resistance bands.
Do cardio exercise regularly. The Physical Activity Guidelines for Americans recommend that adults get 150 minutes of moderate exercise per week. This can include walking, cycling, running, and other aerobic exercises. Setting a daily step goal is one of the best ways I’ve found for people I train to get more active and increase their aerobic capacity.
Add intensity to your workouts. Adding more intensity to your workouts can help you break through fitness plateaus and improve your body composition.
Cut back on processed foods and eat more nutrient-dense foods like fresh or frozen fruits and vegetables, lentils, and lean proteins.

FAQs

How do you calculate actual body fat percentage?
There are many ways you can calculate body fat percentage. The most accurate ways to calculate body fat are using high-tech equipment such as Dual Energy X-ray Absorptiometry, hydrostatic weighing (underwater weighing), or air displacement.
How do I measure my body fat?
You can learn how to calculate body fat using different techniques. Calipers, smart scales, BMI, and circumference measurements are popular ways to measure your body fat at home. For more high-tech methods, Dual-Energy X-ray Absorptiometry and air displacement offer options with a higher rate of accuracy.
Is 20 percent body fat good?
This depends on your age, sex, and health. In general, 20 percent body fat is within a healthy range.

Marnie Kunz is a NASM-certified trainer and USATF- and RRCA-certified running coach based in Brooklyn, NY. Marnie likes helping people get and stay active to enjoy a better quality of life. When she’s not doing fitness things, Marnie enjoys exploring with her dog, a mischievous rescue Akita.

How to Calculate Body Fat: 10 Methods from a Trainer