Ideal Weight Calculator
Find your ideal weight using 5 evidence-based formulas side by side — Devine, Robinson, Miller, Hamwi, and the WHO BMI 18.5–24.9 healthy range.
—
| Formula | Ideal weight | What it is |
|---|---|---|
| Devine (1974) | — | The most-cited clinical formula. |
| Robinson (1983) | — | A revision of Devine using newer data. |
| Miller (1983) | — | Another revision. Tends to run lower. |
| Hamwi (1964) | — | One of the earliest formulas. Tends to run higher. |
| BMI 18.5 – 24.9 | — | WHO healthy range for your height. |
The 5 formulas disagree by —. That spread is normal — no single formula is "the" answer.
About these formulas
Devine (1974) was originally developed for drug-dosing calculations. Robinson, Miller, and Hamwi are revisions using more recent population data. Each gives a single-point estimate and treats frame size as an optional adjustment. The BMI 18.5–24.9 row is fundamentally different — it gives a range based on the WHO healthy band rather than a single number.
For most people, none of these formulas is "right." They're a starting point for a conversation with a clinician about what a healthy weight means for your body, your build, and your goals.
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Why the five formulas disagree
Different populations
Each formula was developed using a different population sample. Devine (1974) used a small group of hospitalized patients; Hamwi used broader clinical data. Different inputs, different outputs.
Different statistical methods
The formulas use different base weights (50 kg for men in Devine, 48 kg in Hamwi) and different per-inch multipliers (2.3 kg in Devine vs. 2.7 kg in Hamwi). These choices reflect different assumptions about build.
No "true" ideal weight
Ideal weight is a moving target — it depends on body composition, ethnicity, age, fitness, and personal goals. A single-point formula can never capture that. The BMI range is a more honest reflection of reality.
Frame size is the biggest modifier
Within any single formula, frame size can shift the result by ±10%. Two people of the same height and sex can reasonably have "ideal weights" 10 kg apart — and both can be healthy.
Use the range, not the target
The BMI 18.5–24.9 row shows a range for a reason. Staying within a band is more sustainable and more scientifically defensible than chasing a single number.
Talk to a clinician
A clinician who knows your personal and family history can give you better guidance than any formula. Use the calculator above as a starting point for that conversation.
Frequently asked questions
What is the most accurate ideal weight formula?
No single formula is "the most accurate." The five formulas shown here disagree by 5–10 kg on average — that's why we show them all side-by-side. The BMI 18.5–24.9 healthy range is often a more honest starting point because it gives a band, not a single number.
Why do the formulas give different numbers?
They were developed using different population samples and statistical methods. Devine (1974) was originally for drug-dosing calculations. Robinson (1983), Miller (1983), and Hamwi (1964) are revisions using more recent data. The disagreement is normal and expected.
How do I know my body frame size?
Measure your wrist circumference: under 17 cm (6.7 in) for men or under 15 cm (5.9 in) for women is typically small-framed; over 20 cm (7.9 in) or 17 cm (6.7 in) is large-framed. Elbow breadth is a more accurate proxy but harder to self-measure. Most people are medium-framed.
Should I aim for the lowest or highest number?
Neither. The BMI 18.5–24.9 healthy range is the most useful — it gives a band you can stay within rather than a target to hit. The single-point formulas (Devine, Robinson, Miller, Hamwi) are starting estimates, not goals.
Is my data private?
Yes. All calculations run in your browser. We never see, store, or transmit your height, sex, or frame choice.