"Ideal weight" sounds like a single number, but the honest answer is a range — and it depends on which formula you ask. The Robinson, Miller and Devine equations were developed decades ago (Devine's for medication dosing) and each gives a slightly different answer for the same height, which is itself the point: healthy weight is a zone, not a bullseye.
Enter your height and sex and this calculator shows all three classic results side by side, plus the weight range that keeps your BMI between 18.5 and 24.9. That BMI-based range is the one most clinicians use today, with the classic formulas as historical context.
Part of the Health Calculators collection on CountCrunch.
The classic formulas
All results are in kilograms. For a 5′9″ (175 cm) man: Robinson ≈ 68 kg, Miller ≈ 67 kg, Devine ≈ 73 kg — a spread of 6 kg from formulas alone.
Why a range beats a single number
Two people of the same height can both be perfectly healthy 5–8 kg apart, depending on frame and muscle. The BMI-based range (18.5–24.9) for 175 cm is about 57–76 kg — wide enough to be useful, narrow enough to mean something. Aim to land comfortably inside it rather than chasing one formula's output.
Body frame matters
Measure your wrist: a larger frame carries healthy weight at the higher end of the range. Very muscular people may sit above these ranges while being lean — check body fat percentage instead of weight alone.
Frequently asked questions
What is my ideal weight for my height?
It is a range, not one number. For example, at 170 cm the BMI healthy range is roughly 53–72 kg. Enter your height above to see the classic formula results alongside the BMI-based range.
Which ideal weight formula is best?
None is definitive — they are historical estimates. The BMI-based range (18.5–24.9) is the most widely used clinical reference today. Treat the classic formulas as context, not prescriptions.
Do these formulas work for athletes?
Not well. They assume average muscularity, so muscular people often land above "ideal" while being very lean. Body fat percentage is the better metric for athletes.
Should men and women use different targets?
The formulas do differ by sex, reflecting average differences in frame and body composition. The BMI range itself is the same for adult men and women.