Ideal weight calculator

What is my ideal weight?

There is no single ideal. Two common references: the CDC's healthy BMI range, and the Devine formula doctors use for "predicted body weight" when dosing some medicines and setting ventilators.

What is the Devine formula?

Men: 50 kg plus 2.3 kg for each inch over 5 feet; women: 45.5 kg plus 2.3 kg per inch. A 5 ft 10 in man gets 73 kg (161 lb); a 5 ft 4 in woman 54.7 kg (121 lb).

What weight range is healthy for my height?

The weights that give a BMI from 18.5 to under 25, the CDC's healthy range. At 5 ft 10 in that is about 129 to 174 pounds.

Why do the results differ?

The Devine formula gives one number from height and sex only; the BMI range is wide and the same for both sexes. Neither accounts for muscle, frame or age.

Should I aim for these numbers?

Use them as a rough guide. A healthy weight for you depends on more than height — talk with your doctor before setting a target.

Does the Devine formula work for someone under 5 feet tall?

It was built around heights of 5 feet and over. Below that the formula still subtracts 2.3 kg for each inch under 5 feet from the base of 50 kg (45.5 kg for women), but it was not designed for that range, so treat the figure with extra caution and lean on the BMI range instead.

Is the Devine weight the same as the ventilator "predicted body weight"?

Nearly. The ARDS Network protocol writes it in centimeters, as 50 kg for men or 45.5 kg for women plus 0.91 kg for every centimeter above 152.4 cm (5 feet). 0.91 kg per centimeter is the same as 2.3 kg per inch, rounded. Clinicians use it to size tidal volumes from height rather than from actual weight, which is a dosing convention, not a goal weight.

Does ideal weight change with age?

Neither reference here uses age. The CDC adult BMI categories apply to people 20 and older regardless of age or sex; for children and teens, BMI is read against growth percentiles instead, so use a child BMI calculator for anyone under 20.

How the two references are calculated

The Devine formula takes only height and sex. Start from 50 kg (men) or 45.5 kg (women), then add 2.3 kg for every inch above 5 feet (60 inches). The healthy range comes from the definition of body mass index, BMI = weight in kg ÷ height in meters squared. Turning that around, weight = BMI × height², so the low end uses a BMI of 18.5 and the high end a BMI just under 25, the CDC limits for the healthy weight category. The table in the calculator also shows BMI 20 and 22 for a mid-range view.

Worked example: 5 ft 8 in

Height 5 ft 8 in is 68 inches, or 172.7 cm, which is 8 inches over 5 feet. For a man, 50 + 2.3 × 8 = 68.4 kg (151 lb). For a woman, 45.5 + 2.3 × 8 = 63.9 kg (141 lb). The BMI range is the same for both: (1.7272 m)² = 2.983; times 18.5 gives 55.2 kg (122 lb), and times 25 (just under) gives 74.6 kg (164 lb). A BMI of 22 is 65.6 kg (145 lb). The Devine weight for the man lands inside the range, and the woman’s is also inside it, but the range is about 42 lb wide, which shows how loosely any single number should be read.

Things to watch

• Do not treat the Devine number as a target. It was derived for drug and ventilator dosing, not as a goal weight for health.
• Check the unit toggle. Entering centimeters while the US mode is selected (or the reverse) gives a nonsense height and a nonsense weight.
• BMI cannot tell muscle from fat, so a muscular person can sit above the range while healthy. The CDC describes BMI as a screening tool, not a diagnosis.
• The result for men and women differs by only 4.5 kg at the same height, while real body composition varies far more than that between individuals.

For general information only — not medical advice. Talk with your doctor or another health professional about your own health. How we check our calculators.

Sources: Devine BJ, Drug Intelligence and Clinical Pharmacy 1974;8:650; the NHLBI ARDS Network protocol for predicted body weight; CDC, Adult BMI Categories. Related tools: BMI calculator, lean body mass calculator, body fat calculator.