Ideal Weight Calculator

Enter your height to see the healthy weight range for adults (BMI 18.5 to 24.9) and compare the four classic ideal body weight formulas, with every step shown.

Example Enter your height to see your own numbers.

Healthy weight for 5 ft 5 in (165.1 cm)

111.2 – 149.6 lb

50.4 – 67.9 kg · the weights that give a BMI of 18.5 to 24.9 at this height

Ideal body weight formulas

125.0 – 132.1 lb

56.7 – 59.9 kg · lowest to highest of 4

Your BMI

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Add your current weight (optional) to compare.

Compared with the range

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Needs your current weight

The four ideal body weight formulas

Ideal body weight formulas for a female, 5 ft 5 in (165.1 cm)
Formula	Calculation	Result	BMI
Devine 197445.5 kg + 2.3 kg × 5	45.5 kg + 2.3 kg × 5	125.7 lb57.0 kg	20.9
Robinson 198349 kg + 1.7 kg × 5	49 kg + 1.7 kg × 5	126.8 lb57.5 kg	21.1
Miller 198353.1 kg + 1.36 kg × 5	53.1 kg + 1.36 kg × 5	132.1 lb59.9 kg	22.0
Hamwi 1964100 lb + 5 lb × 5	100 lb + 5 lb × 5	125.0 lb56.7 kg	20.8

Working

Height: 5 ft × 12 + 5 in = 65 in; × 2.54 = 165.1 cm = 1.651 m.
Height squared: 1.651 × 1.651 = 2.7258 m².
Healthy weight range (BMI 18.5 to 24.9): 18.5 × 2.7258 = 50.4 kg (111.2 lb) to 24.9 × 2.7258 = 67.9 kg (149.6 lb). Pounds = kilograms ÷ 0.45359237.
Inches over 5 ft: 65 − 60 = 5.
Devine 1974 (female): 45.5 kg + 2.3 kg × 5 = 57.0 kg; ÷ 0.45359237 = 125.7 lb.
Robinson 1983 (female): 49 kg + 1.7 kg × 5 = 57.5 kg; ÷ 0.45359237 = 126.8 lb.
Miller 1983 (female): 53.1 kg + 1.36 kg × 5 = 59.9 kg; ÷ 0.45359237 = 132.1 lb.
Hamwi 1964 (female, published in pounds): 100 lb + 5 lb × 5 = 125.0 lb; × 0.45359237 = 56.7 kg.
BMI at each formula weight (kg ÷ 2.7258): Devine 20.9, Robinson 21.1, Miller 22.0, Hamwi 20.8.

For adults aged 20 and over. This is general information, not medical advice, and it does not apply during pregnancy. Weight is only one part of health; talk to a doctor or registered dietitian before setting a weight goal.

How to use the ideal weight calculator

Choose female or male, then enter your height in feet and inches (or switch to centimeters). Adding your current weight is optional; if you do, the calculator also shows your BMI and how far you are from the healthy range. Until you type a height, the example shows a woman who is 5 ft 5 in. Results update as you type, the working underneath shows every step, and the page address keeps your inputs so you can bookmark them. Nothing is sent anywhere; the calculation runs in your browser.

Healthy weight range: the number to focus on

For adults, the CDC and the NIH define a healthy weight as a body mass index between 18.5 and 24.9. BMI is weight divided by height squared, so turning the two cut-offs around gives the range of weights that count as healthy at your height:

lowest healthy weight (kg)  = 18.5 × height (m)²
highest healthy weight (kg) = 24.9 × height (m)²
in pounds: weight (lb) = BMI × height (in)² ÷ 703.07

The range is wide on purpose. BMI is a screening measure: it cannot tell muscle from fat or show where fat is stored, and people inside the range can still have health risks (and people just outside it may not). The CDC describes BMI as a screening tool, not a diagnosis of body fat or health. Your own BMI and category are on the BMI calculator, which also covers the lower cut-offs used for some ethnic groups.

The four ideal body weight formulas

“Ideal body weight” (IBW) formulas are older, simpler rules. Each starts from a base weight at 5 ft (60 in) and adds a fixed amount for every inch above that:

Ideal body weight formula constants
Formula	Men	Women	Created for
Hamwi (1964)	106 lb + 6 lb per inch	100 lb + 5 lb per inch	Diabetes meal planning
Devine (1974)	50 kg + 2.3 kg per inch	45.5 kg + 2.3 kg per inch	Dosing the antibiotic gentamicin
Robinson (1983)	52 kg + 1.9 kg per inch	49 kg + 1.7 kg per inch	Drug dose calculations
Miller (1983)	56.2 kg + 1.41 kg per inch	53.1 kg + 1.36 kg per inch	Drug dose calculations

Hamwi published his rule in pounds, so this calculator uses those original figures. The metric version you will often see (48 kg + 2.7 kg for men, 45.5 kg + 2.2 kg for women) is a rounded conversion that lands within about 2 lb of it at most adult heights. Robinson’s and Miller’s formulas were fitted to Metropolitan Life Insurance height-weight tables (the 1959 and 1983 editions respectively).

These formulas were designed for dosing medicines, not as personal targets. Clinicians still use Devine’s formula to work out doses of some drugs and to set ventilator volumes, because the way certain medicines behave in the body tracks a person’s lean size better than their total weight. A 2000 review in the Annals of Pharmacotherapy traced the equations back to insurance-company height-weight tables and simple rules of thumb. None of them was designed as a weight goal for an individual, which is why this page leads with the BMI range and shows the formulas as a comparison.

Worked example

A man is 5 ft 10 in (70 in, or 177.8 cm) and weighs 185 lb. His height in meters is 1.778, and 1.778² = 3.1613 m².

Healthy range: 18.5 × 3.1613 = 58.5 kg (128.9 lb) up to 24.9 × 3.1613 = 78.7 kg (173.5 lb).
Devine: 50 + 2.3 × 10 = 73.0 kg = 160.9 lb.
Robinson: 52 + 1.9 × 10 = 71.0 kg = 156.5 lb.
Miller: 56.2 + 1.41 × 10 = 70.3 kg = 155.0 lb.
Hamwi: 106 + 6 × 10 = 166.0 lb = 75.3 kg.
His BMI: 185 lb = 83.91 kg, and 83.91 ÷ 3.1613 = 26.5, which is in the overweight group, 11.5 lb above the top of the healthy range.

All four formula results (155.0 to 166.0 lb) sit inside his healthy range, spread over about 11 lb. Select “Male” and enter 5 ft 10 in and 185 lb above to see the same numbers.

Heights under 5 ft

Because every formula starts at 5 ft, there is no agreed way to use them for shorter adults, and practice varies: some clinicians subtract the per-inch amount for each inch under 5 ft, while others use the 5 ft base value. This calculator extends the lines downward and flags the result. For a woman who is 4 ft 10 in, that gives Devine 90.2 lb and Hamwi 90.0 lb, against a healthy BMI range of 88.5 to 119.1 lb. The range is the more reliable guide at these heights.

Tips and limits

Muscle and frame size. Neither BMI nor the formulas account for muscle or bone. A muscular person can be healthy above the range; a waist measurement adds useful information (the body fat calculator uses waist, neck and height).
The formulas diverge with height. Their per-inch amounts differ, so for very tall or short people they can be 20 lb or more apart. Look at them as a spread, not a single answer.
Unit conversions. The calculator converts with 1 lb = 0.45359237 kg and 1 in = 2.54 cm exactly. For quick lookups, see pounds to kilograms and feet to centimeters.
Changes over time. If you are aiming for a different weight, the calorie calculator estimates your daily energy needs. Losing weight without trying is a reason to see a doctor.

Frequently asked questions

What is a healthy weight for my height?

For adults, the CDC and the NIH treat a body mass index (BMI) of 18.5 to 24.9 as healthy weight. At 5 ft 10 in that works out to about 129 to 174 lb; at 5 ft 5 in, about 111 to 150 lb. The range is the same for men and women. Any weight inside it counts as healthy by this measure; there is no single “ideal” number.

Why do the ideal weight formulas give different answers?

Each one is a straight line fitted in a different way: Devine adds 2.3 kg per inch over 5 ft, Hamwi 6 lb (about 2.7 kg) for men, Robinson 1.9 kg and Miller only 1.41 kg. They agree fairly closely around 5 ft 5 in to 5 ft 10 in and drift apart the further you are from that, which is one reason to treat them as rough reference points.

Should I use the Devine formula as my weight-loss goal?

It was not designed for that. Devine’s 1974 formula, and the Robinson and Miller formulas that followed, were created to estimate doses of medicines, and Hamwi’s rule was a quick estimate for diabetes meal planning. None was designed or tested as a personal target. A doctor or registered dietitian can help you set a goal that fits your health, and the calorie calculator can estimate the energy side.

Is the healthy weight range different for men and women?

No. The BMI range of 18.5 to 24.9 is the same for adult men and women, so the healthy weight range depends only on height. The four ideal body weight formulas do have separate male and female versions, which is why the calculator asks for sex.

Does this work for children, teens or pregnancy?

No. It is for adults aged 20 and over. Children and teens are assessed with BMI-for-age percentiles; use the CDC Child and Teen BMI Calculator. During pregnancy, weight-gain advice is based on your weight before pregnancy, so ask your prenatal care provider.

I am under 5 ft. Why does the calculator show a warning?

All four formulas start at 5 ft and add weight for each inch above it. Below 5 ft, clinicians handle them in different ways, and extending the lines downward (as this calculator does, so you can still see them) gives figures the formulas were not designed to produce. The BMI-based healthy range still applies, so use that as your guide.

Sources

Last reviewed 24 September 2026 · Built and checked by the Reeliy team · How we test our tools