Ideal Weight Calculator
See the classic clinical weight formulas side by side — Devine, Robinson, Miller — plus your healthy BMI range.
Check your healthy weight range
Reference points from clinical formulas — not a prescription. The range matters more than any single number.
Formulas Used: Devine, Robinson & Miller
Three classic clinical formulas estimate a reference weight from height and sex. Each starts from a base weight at 5 feet tall and adds a fixed amount per inch above it:
Here's the twist most sites skip: these formulas were built for medicine, not fitness. Devine created his to dose antibiotics (aminoglycosides); hospitals still use it for drug dosing and ventilator settings. Robinson and Miller are statistical refits of height-weight tables. None of them was designed to tell you what you should weigh — that's why this calculator shows all three as a range, plus the BMI-based healthy band.
Worked Example
Profile: woman, 5'6" (167.64 cm) — 6 inches over 5 feet
Devine: 45.5 + 2.3 × 6 = 59.3 kg
Robinson: 49 + 1.7 × 6 = 59.2 kg
Miller: 53.1 + 1.36 × 6 = 61.3 kg
Range: 59.2–61.3 kg (about 130–135 lb). The healthy BMI range at this height is wider: 52.0–70.0 kg. Notice how the three formulas agree within ~2 kg — and how the BMI band gives much more room.
Ideal Weight vs BMI: Which Matters?
BMI is the better health reference. It comes from population health data linking weight ranges to actual disease risk, and it gives you a band (18.5–24.9) instead of a single point. The "ideal weight" formulas give a single number that looks precise but rests on thinner evidence.
That said, BMI has its own blind spot: it can't tell muscle from fat. A lean 95 kg lifter and a sedentary 95 kg person get the same BMI. The most honest picture combines three things: BMI range (population health), body fat percentage (composition — try our Body Fat Calculator), and waist measurement (where the fat sits matters most for health).
Limitations of Ideal Weight Formulas
- They ignore muscle, frame, and age. A broad-framed athlete can be perfectly healthy several kilos above the estimate; an older adult with low muscle can be "in range" yet carry too much fat.
- Below 5 feet they break down — the formulas are anchored at 5 ft, and shorter heights produce unreliable numbers.
- The spread is the message. The formulas disagree by 2–5 kg at the same height. Treating any one of them as the target is false precision.
- They were never health targets. Devine's formula exists so pharmacists dose drugs safely. Using a dosing tool as a beauty standard is a category error.
A Healthy Approach to Weight Goals
If you're setting a weight goal, work with ranges and trends rather than a single "ideal" number:
- Aim for a 3–5 kg band inside the healthy BMI range, not an exact kilo. Bodies fluctuate daily; bands don't punish normal variation.
- Judge by more than the scale: waist trend, how clothes fit, energy, strength, blood markers. The scale is one signal among several.
- Lose slowly: 0.25–0.5 kg per week preserves muscle and is far more sustainable than crash dieting.
- Talk to a professional if you have a lot to lose, a history of disordered eating, or a medical condition — a dietitian personalizes what no formula can.
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Frequently Asked Questions
What is my ideal weight?
There is no single ideal — the classic formulas give a small range. For example, a 5'6" woman lands around 59–61 kg across the three formulas, inside a wider healthy BMI range of 52–70 kg. Enter your height above for your personal range.
How is ideal weight calculated?
The classic formulas start from a base weight at 5 feet tall and add a fixed amount per inch above it. Devine (1974): 50 kg + 2.3 kg per inch for men, 45.5 kg + 2.3 kg for women. Robinson and Miller (1983) use slightly different constants.
What is the ideal weight for a 5'6" woman?
About 59–61 kg (130–135 lb) across the Devine, Robinson, and Miller formulas. Her healthy BMI range is wider: roughly 52–70 kg. Frame size, muscle, and body composition shift where in that band she feels best.
Are ideal weight formulas accurate?
They are rough clinical references, not precise targets. They ignore muscle mass, frame size, and age, and they disagree with each other by a few kilos. Treat the range as a starting reference — body fat percentage and waist measurements tell you more about health.
Ideal weight vs BMI — which should I trust?
BMI. It is based on population health data and gives a range (18.5–24.9) rather than a single point. The "ideal weight" formulas were built for drug dosing, not health targets. For the full picture, combine BMI with body fat percentage and waist measurements.
Sources
- Devine BJ (1974) — Gentamicin therapy; IBW formulas clinical reference (WikEM)
- Ideal Body Weight formulas compared — Devine, Robinson, Miller & Hamwi