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Online Body Fat Percentage Calculator
Estimate your body fat percentage using the BMI-based or US Navy tape method, with category, fat mass, and lean mass — free and instant.
Body Fat
Essential Fat
Athletes
Fitness
Average
Obese
| Body Fat Percentage | 19.7% |
| Body Fat Category | Average |
| Body Fat Mass | 34.7 lbs |
| Lean Body Mass | 99.8 lbs |
| Ideal Body Fat for Given Age | 12.7% |
| Body Fat to Lose to Reach Ideal | 12.3 lbs |
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What Is This Tool?
The Body Fat Percentage Calculator estimates what share of your body weight is fat, using one of two approaches: a BMI-based estimate from your height, weight, age, and gender, or the US Navy method, which adds tape measurements of the neck and waist (and hips for women). Alongside the percentage, it places you on a category scale, and reports your fat mass, lean body mass, and a general age-based reference value. You can work in metric or imperial units and download the result as a PDF. The figures are estimates for general awareness, not a clinical measurement or medical advice.
How to Use This Tool?
- Select your gender and preferred units.
- Enter your age, height, and weight.
- Choose the BMI or US Navy method, adding neck and waist (and hips for women) for US Navy.
- Click Calculate, then download the result as a PDF if needed.
Key Features
- Estimates body fat two ways: a BMI-based method and the US Navy tape-measure method.
- Places the result on a category scale from essential fat through to obese.
- Reports fat mass, lean body mass, and an age-based reference body fat percentage.
- Works in metric or imperial units with gender and age inputs.
- Download the full breakdown as a PDF.
Examples
- A 30-year-old man at 182 cm and 80 kg, using the BMI method, gets about 19.7%, landing in the average category.
- The US Navy method instead uses neck and waist measurements to estimate the same person's body fat.
- For women, the US Navy method also asks for a hip measurement.
- The scale indicator moves to show where the estimated percentage falls among the categories.
Common Use Cases
- Getting a rough baseline of body composition beyond weight alone.
- Tracking changes over time using the same method consistently.
- Comparing how the BMI-based and US Navy methods estimate the same figures.
- Understanding which body fat category an estimate falls into.
- Supporting general fitness awareness alongside other measurements.
Tips & Best Practices
- For the US Navy method, measure the neck and waist (and hips) at the correct spots with a snug, level tape.
- Make sure the waist measurement is at least as large as the neck measurement.
- Stick to one method when comparing results over time, since the two can differ.
- Treat every figure as an estimate rather than an exact measurement.
- For a precise reading, consider a clinical body composition assessment.
Limitations
- Both methods are approximations and can differ from clinical measurements like DEXA scans.
- It accepts ages from 15 to 80, so values outside that range are not supported.
- The age-based reference value is a general guideline, not a personal goal, and healthy ranges vary by individual.
- It is for general information only and is not medical advice.
Frequently Asked Questions
- What is the difference between the BMI and US Navy methods?
- The BMI method estimates body fat from height, weight, age, and gender, while the US Navy method uses tape measurements of the neck and waist, plus hips for women.
- Why does the waist need to be larger than the neck?
- The US Navy formula is based on the difference between waist and neck, so a waist smaller than the neck would not produce a valid estimate.
- How accurate are the results?
- They are reasonable estimates for general awareness, but they are not as precise as clinical methods, so use them as a guide rather than an exact value.
- Can I save my result?
- Yes. Click Download Result as PDF to save the body fat estimate and the full breakdown as a file.
Key Terminology
- Body fat percentage
- The share of your total body weight that is made up of fat.
- Lean body mass
- Everything in your body that is not fat, including muscle, bone, organs, and water.
- US Navy method
- A way to estimate body fat from tape measurements of the neck, waist, and, for women, the hips.
- Essential fat
- The minimum body fat the body needs to function normally.
- Body composition
- The breakdown of the body into fat mass and lean mass, rather than just total weight.