Ideal Weight Calculator Guide
An ideal weight calculator answers a question people have asked for a century: "what should someone my height weigh?" The honest answer is a range, not a number — and the four classic formulas the tools report were never designed for dieting in the first place. This guide explains what our calculator shows, where the formulas come from, and how to use the output without being misled by it.
What the Calculator Shows
Our ideal weight calculator leads with the healthy BMI weight band (BMI 18.5–24.9 converted to kilograms for your height), then lists four formula values as reference points inside it:
| Formula | Year | Men (kg) | Women (kg) |
|---|---|---|---|
| Hamwi | 1964 | 48 + 2.7 per inch over 5 ft | 45.5 + 2.2 per inch over 5 ft |
| Devine | 1974 | 50 + 2.3 per inch over 5 ft | 45.5 + 2.3 per inch over 5 ft |
| Robinson | 1983 | 52 + 1.9 per inch over 5 ft | 49 + 1.7 per inch over 5 ft |
| Miller | 1983 | 56.2 + 1.41 per inch over 5 ft | 53.1 + 1.36 per inch over 5 ft |
All four share one shape — a base weight at five feet plus an increment per inch — and all four were built for clinical work, chiefly drug dosing (the Devine formula's original job), not for judging bodies.
A Worked Example
A man of 180 cm (70.9 in): Hamwi 77.3 kg, Devine 75.0 kg, Robinson 72.6 kg, Miller 71.5 kg — a spread of nearly 6 kg. His healthy BMI band is 59.9–80.7 kg. Every formula value sits comfortably inside the band, which is the correct reading: anywhere in that range is a healthy weight for his height.
How to Use the Result
Use the range as the reference and your current position as the actionable fact: check where you sit with the BMI calculator, and if you are inside the band, a formula value below your weight is not a mandate to cut. Muscular builds should lean on the lean body mass calculator and body fat percent instead — the formulas cannot see composition. The full comparison of range-vs-point thinking lives in the ideal weight vs BMI guide.
Frequently Asked Questions
Which ideal weight formula is best?
Robinson is the most commonly cited modern default, but no formula is best — they are single points from
different eras. The healthy BMI range is the more meaningful reference.
Why is my ideal weight different on every site?
Different sites pick different formulas. At the same height the four classic formulas can spread 5 to 8 kg, so
which one a site shows changes the answer.
Should I diet down to my ideal weight?
Not on the strength of a formula. If your weight is inside the healthy BMI range, a formula value below your
current weight is not evidence you need to lose anything. Discuss goals with a healthcare professional.