Ideal Weight Calculator

Ideal weight calculator at a glance#

What is ideal body weight?#

Ideal body weight (IBW) is an estimate of a healthy weight worked out from your height and sex alone. The formulas behind it date from 1964 to 1983 and grew out of old height and weight tables, some of them from life insurers. Each one gives a single number, so it's a reference point, not a target you must hit.

How do you calculate ideal body weight?#

Start from a base weight for someone 5 ft (152.4 cm) tall and add a fixed amount for every inch above that. The Devine formula, for example, is 50 kg plus 2.3 kg per inch for men and 45.5 kg plus 2.3 kg per inch for women. Enter your sex, age and height above, in feet and inches or in centimeters, and the calculator shows four named formulas plus the healthy weight range from BMI.

What is the ideal weight for a woman who is 5 ft 6 in?#

The four formulas give 129.4 to 135.1 lb (58.7 to 61.3 kg) for a woman who is 5 ft 6 in (167.64 cm). The healthy BMI range for that height is wider, 114.6 to 154.9 lb (52.0 to 70.3 kg).

Where ideal weight formulas come from#

A 2000 review in the Annals of Pharmacotherapy by Pai and Paloucek traces the history. Weight in the old height and weight tables was found to be linked to mortality, which is where the words "desirable" and "ideal" weight come from. Over time, ideal body weight came to stand in for lean body weight in medicine. The way some drugs behave in the body tracked it, and that's how the equations published by Devine in 1974 came into use.

The review's main finding is that the equations look alike because the height and weight tables behind them generally agree. Its conclusion is that any one of them may be used to estimate ideal body weight. None of them knows your build, muscle or body fat, which is why the calculator also shows a range from BMI.

We'll use one person through this page: a 35-year-old woman who is 5 ft 6 in (167.64 cm) tall. That's 6 inches over 5 ft, which keeps the arithmetic easy.

The four formulas in the calculator#

Each formula is a base weight in kilograms for 5 ft plus kilograms per inch above 5 ft. These are the numbers the calculator uses.

For our 5 ft 6 in woman, multiply each per inch figure by 6 and add the base:

• Hamwi (1964): 45.5 + 2.2 × 6 = 58.7 kg, or 129.4 lb
• Robinson (1983): 49 + 1.7 × 6 = 59.2 kg, or 130.5 lb
• Devine (1974): 45.5 + 2.3 × 6 = 59.3 kg, or 130.7 lb
• Miller (1983): 53.1 + 1.36 × 6 = 61.26 kg, or 135.1 lb

The calculator converts kilograms to pounds by multiplying by 2.20462 and rounds to one decimal place. For a man of the same height, the four results are 139.8 to 142.6 lb.

Two notes on the formulas#

In the calculator, Hamwi is 48 kg plus 2.7 kg per inch for men and 45.5 kg plus 2.2 kg per inch for women. In pounds, that's close to 106 lb plus 6 lb per inch and 100 lb plus 5 lb per inch. Worked in pounds, our example is 100 + 5 × 6 = 130 lb, against the calculator's 129.4.

The Robinson figures in the calculator, 52 kg plus 1.9 kg per inch for men and 49 kg plus 1.7 kg per inch for women, are rounded. The 1983 paper by Robinson and colleagues, built from Metropolitan Life Insurance height and weight tables, gives 51.65 kg plus 1.85 kg per inch for men and 48.67 kg plus 1.65 kg per inch for women. For our example, the paper's version gives 58.57 kg, or 129.1 lb, against the calculator's 130.5.

The healthy BMI range row#

The last row of the result is a range, not a single weight. For adults it's every weight that puts body mass index (BMI) between 18.5 and 25, the CDC's healthy weight range. Multiply 18.5 and 25 by your height in meters squared: at 1.6764 m, 18.5 × 2.8103 = 52.0 kg and 25 × 2.8103 = 70.3 kg, or 114.6 to 154.9 lb.

All four formula results for our example land inside that range, nearer its middle than either end. The formulas each pick one point, while BMI marks out the span the CDC treats as a healthy weight for that height. For your own BMI and category, use the BMI calculator.

For anyone 20 or younger, the calculator switches this row to the CDC's BMI-for-age percentiles: the range runs from the 5th to the 85th percentile for that age and sex. The four named formulas don't use age at all, so they don't change.

Under 5 feet#

The formulas all start at 5 ft, so below 152.4 cm the calculator shows only the BMI-based range. A 35-year-old woman who is 4 ft 11 in gets a healthy weight range of 91.6 to 123.8 lb.

Ideal weight by height#

Here's what the calculator gives for common heights. The formula columns show the lowest and highest of the four results for women and for men, and the last column is the healthy BMI range, which is the same for both sexes in adults.

What ideal weight leaves out#

A height formula can't tell you how much of your weight is muscle and how much is fat. Two people of the same height and sex get the same ideal weight, whether one lifts weights and the other doesn't. For a fuller picture, a body fat analysis looks at body composition instead of weight alone. You can try a simple one at home with the body fat percentage calculator, which works from your BMI or from body measurements taken with a tape.

If you're aiming at a weight, the calorie calculator gives daily calories for losing or gaining at a set weekly rate.

This gives an estimate, not medical advice. A doctor can tell you what the number means for you.

Sources#

• Pai MP, Paloucek FP. The origin of the "ideal" body weight equations. Ann Pharmacother, 2000
• Robinson JD, et al. Determination of ideal body weight for drug dosage calculations. Am J Hosp Pharm, 1983
• CDC, Adult BMI Categories

Frequently asked questions#

Which ideal weight formula is most accurate?#

None is more correct for a given person. The 2000 review by Pai and Paloucek found that the equations are similar because the height and weight tables they came from generally agree. It concluded that any one of them may be used to estimate ideal body weight. Reading all four and the BMI range together gives a better sense of the spread.

What is the ideal weight for a man who is 5 ft 10 in?#

The calculator gives 155 lb (Miller), 156.5 lb (Robinson), 160.9 lb (Devine) and 165.3 lb (Hamwi) for a man who is 5 ft 10 in (177.8 cm). The healthy BMI range for that height is 128.9 to 174.2 lb.

How do I calculate ideal weight in kg?#

Count the inches over 5 ft, multiply by the formula's kilograms per inch, and add the base. For a woman at 5 ft 6 in with the Devine formula: 45.5 + 2.3 × 6 = 59.3 kg. With height in centimeters, inches over 5 ft = (height in cm − 152.4) ÷ 2.54. Switch the calculator to metric and it shows every result in kilograms.

Is ideal body weight the same as a healthy BMI?#

No. An ideal weight formula gives one number for your height and sex, and a healthy BMI covers a range of weights. For a 5 ft 6 in woman, the four formulas give 129.4 to 135.1 lb, all inside the BMI range of 114.6 to 154.9 lb.

Does age change ideal weight?#

Not in the four formulas, which use only height and sex. The calculator uses age for one thing: at 20 or younger, the healthy weight range row switches from adult BMI cutoffs to the CDC's percentiles for that age and sex.

Why is the ideal weight different for men and women?#

Each formula has separate numbers for men and women, so the base weights and the per inch amounts differ. At 5 ft 6 in, the four formulas give a woman 129.4 to 135.1 lb and a man 139.8 to 142.6 lb.