GenzeeIdeal Weight Calculator
Your "ideal" body weight according to four widely used medical formulas — Devine, Robinson, Hamwi and the BMI healthy range — side by side.
Healthy BMI range
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Where "ideal weight" formulas come from
None of the classic ideal-weight formulas began as fitness advice. The Devine formula (1974) was created to dose medications; Hamwi (1964) was a quick clinical rule of thumb; Robinson (1983) refined Devine against actuarial data. All three share a structure — a base weight at five feet plus an increment per extra inch — and all three still appear in hospitals, insurance tables and drug-dosing charts. The fourth reference on this page, the BMI 18.5–24.9 range, is the modern population-health standard and arguably the most useful of the lot, because it gives a range rather than a single loaded number.
How to use this calculator
Enter your height and sex. The tool shows the three formula weights and the BMI-based healthy range together. Expect them to disagree by a few kilograms — that disagreement is the honest takeaway: "ideal" is a band, not a bullseye.
The formulas
Robinson: men 52 + 1.9 · women 49 + 1.7
Hamwi: men 48 + 2.7 · women 45.5 + 2.2
BMI range: 18.5×h² to 24.9×h² (h in metres)
Worked example
A man of 175 cm (68.9 inches, 8.9 over five feet): Devine gives 50 + 2.3 × 8.9 ≈ 70.5 kg; Robinson ≈ 68.9 kg; Hamwi ≈ 72.0 kg; and the healthy BMI range spans 56.7 – 76.3 kg. All three formula values sit comfortably inside the BMI band — a 175 cm man anywhere in the upper 60s to low 70s is, by every standard measure, at a healthy weight. Someone at 85 kg is above all four references, and someone at 54 kg below all of them; both would benefit more from the trend than the label.
How to actually use these numbers
Treat the BMI range as the meaningful target zone and the formulas as historical reference points. Body composition matters more than the scale: a muscular 175 cm man can be perfectly healthy at 80 kg, and South Asian populations see metabolic risk rise at lower weights than Western charts assume — a reason to aim for the middle of the range rather than its top. Combine this page with the BMI calculator (which uses your actual weight) and the calorie calculator (which turns any goal into a daily eating target), and read what the formulas really say for the full story.
Frequently asked questions
Why do the formulas give different answers?
Each was calibrated on different data for different purposes decades apart. A spread of 2–4 kg is normal — read them as a band, not competing truths.
Which formula should I trust most?
For health purposes, the BMI 18.5–24.9 range — it's the modern evidence-based standard. The named formulas survive mainly in clinical dosing contexts.
Does frame size or muscle change my ideal weight?
Yes. Larger frames and muscular builds sit healthily above formula values; the formulas assume average build. Waist measurement and body-fat percentage capture what the scale misses.
Are these formulas valid for South Asians?
The formulas were derived from Western data. South Asian health guidance often flags risk from BMI 23, so aiming for the middle of the healthy range is a sensible adaptation.
What if I'm far from every number shown?
Don't crash-diet toward a formula. Set a modest first target (5% of body weight), pair it with the calorie calculator, and involve a doctor — especially if other conditions are in play.