What is a body fat calculator?
A body fat calculator estimates what share of your total body weight is fat. This free online body fat calculator uses the US Navy method, a tape-measure formula developed by the US Naval Health Research Center and still used by the US Navy and other armed forces to screen personnel. You only need a flexible tape and a minute or two: enter your height, neck and waist (plus hip for women) in centimetres or inches, and the tool returns your body fat percentage, fat mass and lean mass in kg or pounds, and the category you fall into on the body fat chart.
Because it needs no machine, caliper or scale, it is one of the quickest ways to track progress at home. It works as a body fat calculator for men and a body fat calculator for women, and it is equally useful for readers in India, the US or anywhere else, as long as you measure carefully.
What is body fat percentage?
Body fat percentage is your fat mass divided by your total body weight, multiplied by 100. If you weigh 75 kg and carry 13 kg of fat, your body fat percentage is about 17%. The rest – muscle, bone, organs, water – is called lean body mass. Some fat is essential: it protects organs, stores energy and makes hormones. Essential fat is roughly 2–5% for men and 10–13% for women, which is why a healthy body fat percentage for women is always higher than for men.
How to use this body fat calculator
- Choose your sex and your units (cm and kg, or inches and pounds).
- Enter your height without shoes.
- Neck: measure just below the Adam's apple, with the tape sloping slightly down to the front. This answers the common question of how to measure the neck for a body fat calculator.
- Waist: men measure horizontally at the level of the navel; women measure at the narrowest point of the waist. Stand relaxed and do not pull the stomach in.
- Hip (women only): measure around the widest part of the buttocks.
- Optionally add your weight to see fat mass, lean mass and how much fat to lose to reach the fitness range.
Take each measurement two or three times and use the average. Measure in the morning, before eating, for the most repeatable results.
Body fat calculator formula (US Navy method)
With all measurements in centimetres, the US Navy body fat formula is:
Men: BF% = 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450
Women: BF% = 495 ÷ (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450
- waist, neck, hip, height = circumferences and height in cm (inches are converted by × 2.54)
- log10 = the base-10 logarithm
The inner part of the equation estimates body density; the 495 ÷ density − 450 step is the Siri equation that converts density into body fat percentage. This is the same army body fat calculator formula used for fitness standards, just written in metric units.
Worked example: body fat calculator for men
A man is 178 cm tall with a 38 cm neck and 86 cm waist. Waist − neck = 48, log10(48) = 1.6812 and log10(178) = 2.2504. The denominator is 1.0324 − 0.19077 × 1.6812 + 0.15456 × 2.2504 = 1.0595. So BF% = 495 ÷ 1.0595 − 450 = 17.2%, which is in the fitness range. At 75 kg he carries about 12.9 kg of fat and 62.1 kg of lean mass.
Worked example: body fat calculator for women
A woman is 163 cm tall with a 32 cm neck, 72 cm waist and 98 cm hip. Waist + hip − neck = 138. BF% = 495 ÷ (1.29579 − 0.35004 × 2.1399 + 0.221 × 2.2122) − 450 ≈ 28.0%, in the average range.
Body fat percentage chart
Use this body fat chart from the American Council on Exercise to interpret your result:
| Category | Women | Men |
|---|---|---|
| Essential fat | 10–13% | 2–5% |
| Athletes | 14–20% | 6–13% |
| Fitness | 21–24% | 14–17% |
| Average | 25–31% | 18–24% |
| Obese | 32% and above | 25% and above |
What should my body fat percentage be?
For most adults, the best body fat percentage for men is roughly 10–20%, and for women roughly 18–28%. Body fat naturally rises a little with age, so a 55-year-old in the average band is often in good health. Very low numbers are not a goal for most people; dropping below the essential range harms hormones and immunity.
Body fat calculator for Indians
Research on South Asians shows that Indians tend to carry more body fat – especially around the abdomen – at the same BMI as Europeans. That is why Indian guidelines use a lower BMI cut-off of 23 for overweight. A body fat calculator for Indians is therefore more informative than BMI alone: if your waist is large, your body fat percentage may be high even when your weight looks normal.
Body fat calculator vs BMI
BMI uses only height and weight in kg, so it cannot tell muscle from fat: a muscular athlete and an inactive person of the same height and weight get the same BMI. A body fat calculator with waist and neck measurements looks at where you carry size, which is closer to what matters for health. Use both: BMI for a quick screen, body fat percentage to see body composition. Our ideal weight calculator adds a target-weight view.
How accurate is an online body fat calculator?
The US Navy method is usually within about 3–4 percentage points of a DEXA scan for most people, which makes it one of the most practical free methods. Accuracy drops for very lean bodybuilders and for people with very high body fat. Other ways to calculate body fat percentage include:
- DEXA scan – the clinical reference, done in hospitals and diagnostic centres.
- Skinfold calipers – the Jackson-Pollock 3- or 7-site formulas; accurate in trained hands.
- Bioimpedance machines and body fat scales – the body fat calculator machines at gyms; convenient but affected by hydration.
- Photo or visual estimates – rough at best.
Whatever method you choose, stick with it and track the trend over weeks rather than a single reading.
How much fat to lose?
Enter your weight and the calculator shows how much fat you need to lose to reach the top of the fitness range, assuming you keep your lean mass. A safe rate is about 0.5–1% of body weight per week. Pair a modest calorie deficit from the TDEE calculator with enough protein and strength training so the weight you lose is fat, not muscle.
Common questions about measuring body fat
How to calculate body fat percentage with height and weight
Height and weight alone only give BMI, so a body fat calculator with BMI (the Deurenberg equation, BF% = 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4) is a rough guess. This BMI method often misses by 5% or more in muscular people, which is why this tool asks for tape measurements. Any body fat calculator that works without neck and waist measurements is less reliable.
Body fat calculator for men in India and for women
The same formula works for Indian men and women and for any country. In the body fat calculator, men enter neck and waist; women (female) add the hip, because women store more fat on the hips and thighs.
Body fat calculator in kg and inches
Choose metric to enter kg and centimetres, or imperial for inches and pounds. The result is identical, since inches are converted to cm first.
Calipers, machines and scales
A body fat calculator caliper test (a skin fold test) pinches the skin at 3–7 sites and applies the Jackson-Pollock equations. A machine or smart scale at the gym uses a tiny electric current (bioimpedance). A DEXA scan is the clinical gold standard. The free tape method here sits between these in accuracy and costs nothing.
Body fat calculator by image or photo
Photo-based tools compare your picture to reference photos. A body fat calculator that works this way gives only a visual guess, and it can be off by 5% or more; tape measurements are far more repeatable.
Body fat calculator for teens and kids
The US Navy method was built for adults. Teens and kids should be assessed with age-specific BMI percentiles instead, so use this tool for adults only.
Body fat calculator goal: how much to lose
Pick a target category from the chart as your goal. The result shows how much fat to lose in kg. The body fat calculator is a quick and easy tool for seeing progress: remeasure every two weeks.
What is body fat made of and what is body fat mass?
Body fat is made of fat cells (adipocytes) that store triglycerides. Body fat mass is the weight of that fat in kg – body weight × body fat percentage ÷ 100 – and the rest is lean mass. The body fat ratio is simply fat mass compared with total weight.
What is the most accurate body fat calculator?
DEXA is the most accurate test. Among free methods, the US Navy method is one of the most accurate options online, which is why it is the method used here. To keep your readings accurate enough for tracking, use the same tape, the same time of day and the same person measuring.
Body fat calculator with calipers (Jackson-Pollock 3-site)
If you have skinfold calipers, the Jackson-Pollock 3-site formula is a common alternative to tape measurements. Measure three sites on the right side, in millimetres, and add them up (S):
- Men: chest, abdomen, thigh. Body density = 1.10938 − 0.0008267 × S + 0.0000016 × S² − 0.0002574 × age.
- Women: triceps, suprailiac, thigh. Body density = 1.0994921 − 0.0009929 × S + 0.0000023 × S² − 0.0001392 × age.
Body fat % = 495 ÷ body density − 450 (Siri equation)
Example: a 30-year-old man with S = 50 mm has a body density of about 1.0643, which gives about 15.1% body fat. Caliper results depend heavily on technique, so take each site two or three times and use the average.
Body fat calculator YMCA formula
The YMCA method needs only your waist and weight, in inches and pounds:
Men: body fat % = (4.15 × waist − 0.082 × weight − 98.42) ÷ weight × 100
Women: body fat % = (4.15 × waist − 0.082 × weight − 76.76) ÷ weight × 100
A man with a 34-inch waist weighing 170 lb gets (141.1 − 13.94 − 98.42) ÷ 170 ≈ 16.9%. It is quick but less accurate than the Navy method above, because it ignores height and neck size.
Body fat calculator in kg with age
The Navy method does not use age, but age-based formulas such as the BMI-based Deurenberg equation do: body fat % = 1.2 × BMI + 0.23 × age − 10.8 × sex − 5.4 (sex = 1 for men, 0 for women). A 40-year-old woman weighing 65 kg at 160 cm has a BMI of 25.4, so the estimate is about 34.3%. Use it only as a rough check; check your BMI with the body mass index calculator online.
Body fat calculator machine, device or app: what to use
| Method | Typical error | Where |
|---|---|---|
| DEXA scan | ±1–2% | Hospitals and diagnostic centres |
| Skinfold calipers (trained tester) | ±3–4% | Gyms, dietitians |
| Bioimpedance machine (InBody-type) | ±3–5% | Gyms, clinics |
| Smart scale or handheld device | ±4–8% | Home |
| Tape-measure formula (this page) | ±3–4% | Home |
An app or body fat calculator instrument at home is fine for tracking trends; measure at the same time of day, before eating or exercise. To find a body fat calculator machine near me, look for DEXA or body composition tests at diagnostic labs, sports medicine clinics or larger gyms; many offer a one-off scan.
Frequently asked questions
How is body fat calculated?
This calculator uses the US Navy formula, which estimates body density from your height and neck and waist circumferences (plus hip for women), then converts density to body fat percentage with the Siri equation.
How can I calculate body fat percentage at home without equipment?
All you need is a tape measure. Measure your neck, waist and (for women) hips, enter them with your height, and the US Navy method gives an estimate usually within 3–4% of a DEXA scan.
What is a good body fat percentage for men?
Around 14–17% is the fitness range and 6–13% is athletic. Most healthy adult men sit between 10% and 20%.
What is a good body fat percentage for women?
Women need more essential fat. 21–24% is the fitness range and 14–20% is athletic; 18–28% is a healthy range for most women.
Can I calculate body fat with height and weight only?
Only roughly, through BMI-based equations, which cannot separate muscle from fat. Waist and neck measurements give a much better estimate.
Does the calculator work in inches and kg?
Yes. Choose metric (cm, kg) or imperial (inches, lb). Inches are converted to centimetres before the formula is applied.
Is an online body fat calculator accurate?
It is a good estimate for most people and ideal for tracking change over time, but it is not a clinical test. For precise measurement use a DEXA scan.
How do I calculate body fat with calipers?
Add the three Jackson-Pollock skinfolds, put the sum into the body density equation for your sex and age, then use body fat % = 495 ÷ density − 450.
What is the YMCA body fat formula?
Men: (4.15 × waist in inches − 0.082 × weight in lb − 98.42) ÷ weight × 100. Women use 76.76 instead of 98.42.
Last updated 2026-09-18