Measure your neck and waist with a tape (women measure hips too), add your height, weight and age, and see your body fat percentage. You also get fat mass, lean mass, your category and a second estimate from BMI.
Choose male or female and enter age, weight and height.
Measure around the neck and the waist in centimetres. Women measure the hips as well.
Read the body fat percentage, fat mass and lean mass.
Compare your figure with the category bar and the ideal for your age.
Men (cm): 495 ÷ (1.0324 − 0.19077 × log(waist − neck) + 0.15456 × log(height)) − 450
Women (cm): 495 ÷ (1.29579 − 0.35004 × log(waist + hip − neck) + 0.221 × log(height)) − 450
BMI method (adults): 1.2 × BMI + 0.23 × age − 16.2 for men, or − 5.4 for women
The body fat calculator estimates what share of your weight is fat, using only a measuring tape and a weighing scale. You enter your height, weight, age and the distance around your neck and waist (women also measure the hips). It then applies the tape formula developed for the United States Navy, which is widely used because it needs no costly equipment.
Along with the percentage, you see how many kilograms of your body are fat and how many are lean tissue such as muscle, bone and water. The result is placed in a category from athlete to obese, and compared with a typical ideal figure for your age. A second estimate based on BMI is shown beside it, so you can see how the two methods compare. If you are muscular, the tape method is usually the fairer of the two.
1. Measure your height without shoes and your weight in light clothing.
2. Measure around the neck just below the Adam's apple, keeping the tape snug but not tight.
3. Measure the waist: men at the level of the navel, women at the narrowest point. Breathe out normally and do not pull the stomach in.
4. Women also measure around the widest part of the hips.
5. Men: subtract neck from waist. Women: add waist and hip, then subtract neck.
6. Put this figure and the height into the tape formula to get the body fat percentage.
7. Multiply the percentage by your weight to get the fat mass; the rest is lean mass.
Most extra fat in the body collects around the abdomen, and for women around the hips as well. The neck, on the other hand, changes little with fat and reflects the frame and muscle of the person. So the gap between waist and neck is a good sign of how much fat is being carried. Researchers compared these tape readings with underwater weighing of many people and fitted a formula that links the two.
Body weight is made of two parts. Fat mass is the stored fat. Lean mass is everything else: muscle, bone, organs, blood and water. Two people of the same height and weight can look very different if one has more muscle and the other more fat. This is why body fat percentage tells you more than weight or BMI alone, and why a weighing scale can stay the same even while you are losing fat and gaining muscle.
The body needs some fat to cushion organs, keep warm and make hormones, so very low figures are not healthy either. Men usually fall between 14 and 24 per cent, and women between 21 and 31 per cent, because women naturally carry more. The figure creeps up with age as muscle reduces. Regular strength exercise and enough protein help to hold on to muscle, which keeps the percentage in check.
Suresh, a 45-year-old bank officer in Coimbatore, is 173 cm tall and weighs 82 kg. With a tailor's tape he measures 40 cm around the neck and 96 cm around the waist at the navel.
Subtract the neck from the waist: 96 − 40 = 56 cm
Put this and the height into the tape formula: 495 ÷ (1.0324 − 0.19077 × log(56) + 0.15456 × log(173)) − 450
Body fat percentage: = 23.8%
Fat mass = weight × body fat %: 82 × 23.8% = 19.5 kg
Lean mass = weight − fat mass: 82 − 19.5 = 62.5 kg
Answer: Body fat (tape method) 23.8%; Fat mass 19.5 kg; Lean mass 62.5 kg
Pulling the stomach in while measuring the waist, which gives a falsely low result.
Holding the tape slanted or too tight around the body.
Measuring over thick clothes instead of on bare skin or a thin layer.
Entering inches when the boxes ask for centimetres. Multiply inches by 2.54 first.
Treating the result as exact. It is an estimate and can be off by a few percentage points.
Tracking fat loss during a fitness programme, where weight alone can mislead.
Checking whether a high BMI is due to muscle or to fat.
Setting a realistic target weight based on lean mass.
Fitness tests that use tape measurements.
Comparing your figure with typical values for your age.
How accurate is this compared to a real body fat test?
It is an estimate based on large groups of people, not a direct measurement of you. Methods like DEXA scans or skinfold callipers give a more accurate result for you personally.