Ideal Weight: How Much Should You Weigh?

Ideal-weight formulas give a reference weight for your height, but they were never meant as personal prescriptions. Here is where the Devine, Robinson and Hamwi formulas come from, how to calculate each, and how to turn the results into a realistic target range.

What "Ideal Weight" Really Means

The idea of an ideal weight grew out of insurance industry tables in the early twentieth century, when companies wanted to estimate health risk based on height and weight. Over time, clinicians developed simpler formulas to estimate a "reasonable" weight for a given height, originally to help calculate medication dosages rather than to define personal fitness goals.

That history explains the main limitation: these are population-level estimates built around average body composition. They don't know whether you are a heavily muscled rower, recovering from illness, or built with a wider or narrower frame than average.

The Common Ideal Weight Formulas

Several formulas have become standard references. They all use your height above five feet (60 inches) as the main input and differ slightly in their constants. Here are the three most cited.

Devine Formula (1974): Originally created for drug dosing, this is the most widely used.

Men: 50 kg + 2.3 kg for each inch over 5 feet
Women: 45.5 kg + 2.3 kg for each inch over 5 feet

Robinson Formula (1983): A refinement of Devine.

Men: 52 kg + 1.9 kg for each inch over 5 feet
Women: 49 kg + 1.7 kg for each inch over 5 feet

Hamwi Formula (1964): Developed for quick clinical estimates.

Men: 48 kg + 2.7 kg for each inch over 5 feet
Women: 45.5 kg + 2.2 kg for each inch over 5 feet

They give different answers for the same person, which is a useful reminder that "ideal" is a range rather than a point.

A Worked Example

Take a man who is 5 feet 10 inches tall. That's 10 inches over 5 feet.

Devine: 50 + (2.3 × 10) = 50 + 23 = 73 kg (about 161 lbs)

Robinson: 52 + (1.9 × 10) = 52 + 19 = 71 kg (about 157 lbs)

Hamwi: 48 + (2.7 × 10) = 48 + 27 = 75 kg (about 165 lbs)

So depending on the formula, this man's reference weight is about 71 to 75 kg. For comparison, the BMI healthy range at 5'10" runs from about 59 to 79 kg (129–173 pounds). The ideal weight calculator takes height (inches, or centimetres in metric mode) and sex, lets you choose Devine, Robinson, Hamwi or Miller (1983: 56.2 kg + 1.41 kg per inch for men, 53.1 kg + 1.36 kg per inch for women), adjusts by ±5% for a small or large frame, and reports the result in pounds (kilograms in metric mode). For the 5'10" man above it returns 161 lb (Devine), 157 lb (Robinson), 165 lb (Hamwi) or 155 lb (Miller) with a medium frame.

Ideal Weight Ranges by Height

The span of the three formulas' results (women's lowest to men's highest) by height, as ballpark figures:

5'0" (152 cm): about 45–52 kg (100–115 lbs)
5'4" (163 cm): about 54–60 kg (120–131 lbs)
5'8" (173 cm): about 63–70 kg (138–153 lbs)
6'0" (183 cm): about 69–80 kg (153–177 lbs)
6'4" (193 cm): about 76–91 kg (168–201 lbs)

Women's results fall toward the lower end of each band and men's toward the higher end.

Why Frame Size, Muscle, and Age Matter

The formulas above intentionally ignore three big variables, so you have to add them back in yourself.

Frame size. Two people of identical height can have very different bone structures. Someone with broad shoulders and thick wrists will healthily carry more weight than someone with a slight, narrow frame. A common rule of thumb: add about 10% for a large frame and subtract about 10% for a small frame.

Muscle mass. Muscle is denser than fat, so a strength athlete may weigh well above the formula result with little body fat; for them the formula doesn't apply.

Age and life stage. Pregnancy, recovery from illness and some medications change the target, and reference ranges for older adults are not the same as for people in their twenties.

Ideal Weight vs. BMI vs. Body Composition

These three concepts are related but answer different questions.

Ideal weight formulas give you a target weight in pounds or kilograms based on height and sex. They're concrete and easy to act on but blind to body composition.

BMI takes your actual weight and height and sorts you into a category. It's useful for screening but, like the ideal weight formulas, can't tell muscle from fat. The BMI calculator gives your number.

Body composition measures what your weight is actually made of: the percentage that is fat versus lean mass. This is the most informative of the three, because two people at the same "ideal" weight can have dramatically different amounts of body fat. Tools like skinfold calipers, bioelectrical impedance scales, and DEXA scans estimate this directly.

The practical takeaway: use ideal weight and BMI as quick screens, but lean on body composition and how you feel and perform when you want a real answer.

Setting a Realistic Target

Once you have a sense of your ideal weight range, turn it into a plan you can actually live with.

Aim for a range, not a single number. Your weight naturally fluctuates a kilogram or two day to day from water and food. A range absorbs that noise and reduces frustration.

Adjust for your reality. Factor in your frame size, training, age, and health history. If the formula says 70 kg but you're a heavily muscled lifter sitting comfortably at 78 kg with low body fat, the formula is wrong, not you.

Change slowly. The CDC notes that people who lose about 1 to 2 pounds (0.5 to 1 kg) a week are more likely to keep it off.

Track more than the scale. Notice your energy, strength, sleep, and how clothes fit. These often reflect progress before the number moves.

Check in with a professional. If you have significant weight to gain or lose, or any underlying health conditions, a doctor or dietitian can tailor a target far better than any formula; nothing here is a medical recommendation.