What “ideal weight” actually means
There is no single ideal weight — there's a healthy range. The headline result is the weight band corresponding to a BMI of 18.5–25, the range epidemiology associates with the lowest weight-related health risk for most adults. The four named formulas below it are single points inside (or near) that band, each from a different era of clinical research.
Where the formulas come from
The Devine formula (1974) was created to dose medications by body size and is still used in pharmacology today — that's its real job, not aesthetics. Hamwi (1964) came from a quick bedside method for diabetic patients. Robinson and Miller (both 1983) are statistical refinements of Devine against insurance mortality tables. All four share one structure: a base weight at 5 feet plus an increment per inch above it — which is why they diverge most for very short and very tall people, where the linear assumption strains.
What they can't see
None of these formulas know your muscle mass, bone structure, or body composition. A rugby player and a marathon runner of identical height get identical “ideal weights” — which tells you how seriously to take a single number. If body composition is the real question, the body fat calculator answers it far better, and your TDEE plus a sensible deficit or surplus is how you move toward whatever target you choose.
Frequently asked questions
Which ideal weight formula is the most accurate?
None is “accurate” in a medical sense — they're linear approximations built for drug dosing and bedside estimates. The healthy BMI range is the only result here backed by outcome data, which is why it's the headline. Use the formula average as a reference point, not a target.
Why is my ideal weight different on every calculator?
Different sites pick different formulas or only show one. We show all four plus the BMI band so you can see the spread — typically 3–6 kg between formulas — instead of mistaking one arbitrary point for precision.
Does ideal weight account for muscle?
No. Every formula here uses only height and sex. Muscular people routinely exceed these numbers while being perfectly healthy — body fat percentage is the better lens for body composition.
Should I diet down to my ideal weight?
Not on these numbers alone. If you're inside the healthy BMI band, weight per se is rarely the issue. If you do have a change in mind, set the pace with the weight loss calculator and let your real measured progress — not a 1974 formula — drive adjustments.
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