BodyCalWhat this ideal weight calculator does
"How much should I weigh?" has been answered differently by four generations of clinical researchers. Rather than picking one formula and pretending it's gospel, this calculator runs all four classical equations — Devine, Robinson, Miller, and Hamwi — shows their average, and overlays your healthy BMI weight range on an interactive chart so you can see how the estimates relate to the range modern medicine actually uses.
How the formulas work
All four formulas share the same structure: a base weight at 5 feet (152.4 cm) plus an increment for every inch above that. For men and women respectively:
- Devine (1974): 50 kg / 45.5 kg + 2.3 kg per inch over 5 ft
- Robinson (1983): 52 kg / 49 kg + 1.9 / 1.7 kg per inch over 5 ft
- Miller (1983): 56.2 kg / 53.1 kg + 1.41 / 1.36 kg per inch over 5 ft
- Hamwi (1964): 48 kg / 45.5 kg + 2.7 / 2.2 kg per inch over 5 ft
The Devine formula was originally created for calculating medication doses — a reminder that "ideal weight" began as a clinical convenience, not a beauty standard. The healthy range shown alongside them is simply the weight that gives a BMI of 18.5–24.9 at your height.
A worked example
For a 168 cm (5'6") woman: Devine gives 59.3 kg, Robinson 59.2 kg, Miller 61.3 kg, and Hamwi 58.7 kg — an average of about 59.6 kg (131 lb). Her healthy BMI range spans roughly 52–70 kg (115–155 lb). Notice how all four point estimates cluster near the middle of the range: the formulas and modern BMI guidance largely agree.
Why a range beats a single number
Two people of identical height can both be perfectly healthy 15 kg apart, depending on muscle mass, bone density, and frame size. Health outcomes research consistently supports ranges, not points: anywhere inside the healthy BMI band carries broadly similar risk for most people. Use the formula average as a directional reference, the range as your actual target zone, and body composition or waist-to-height ratio as the tiebreaker when the scale and the mirror disagree.
Common mistakes to avoid
- Treating the estimate as a deadline.If you're far from the range, aim first for a 5–10% loss — that's where most of the measurable health improvement happens.
- Ignoring body composition. Gaining 3 kg of muscle while losing 3 kg of fat leaves the scale unchanged and your health dramatically improved.
- Comparing across sexes or heights. The increments differ by formula and sex; your number is yours alone.
- Using adult formulas for teenagers. Under-18s need growth-chart percentiles, not these equations.
Turning a target into a plan
Once you've picked a realistic goal weight from your healthy range, the calorie deficit calculator converts it into a daily calorie budget and a week-by-week forecast with a predicted finish date. Check your starting point on the BMI calculator, and support the whole process with proper hydration via the water intake calculator.