Ideal Weight Calculator
Four ideal weight formulas, and how far they differ.
Ideal Weight Calculator runs the Devine, Robinson, Miller and Hamwi formulas side by side for your height and sex, shows how far apart their answers fall, and sets the healthy BMI range for the same height alongside them. Every calculation happens in your browser and nothing is uploaded.
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Runs entirely on your device. No file or text you enter here is uploaded. How to verify it.
This is a calculation tool, not medical advice. The result is an estimate from a published formula and cannot account for your individual circumstances. Talk to a healthcare professional about anything that matters.
How to use Ideal Weight Calculator
- Choose centimetres or feet and inches.
- Enter your height and sex.
- Compare the four answers with the healthy BMI range shown beside them.
Questions about Ideal Weight Calculator
Why do the four formulas disagree?
Each one is a base weight at five feet plus a fixed amount for every inch above that, and they were fitted to different reference tables in different decades. They agree near the middle of the height range and drift apart at the extremes. The tool shows that spread rather than hiding it behind a single number.
What were these formulas actually written for?
Drug dosing. Devine published his in 1974 in a letter about gentamicin, because dosing an antibiotic by actual body weight overdoses someone whose extra tissue is fat and does not take up the drug. They survive in intensive care for ventilator tidal volumes and in some chemotherapy protocols.
Should I use one as a goal weight?
No. Each returns exactly one number for a given height and a binary sex, and takes no account of build, muscle, bone density or age. A lean, muscular person routinely lands well above all four. The healthy BMI band shown alongside is wider and closer to what the evidence supports.
Why is the BMI range so much wider?
Because weight scales with the square of height while these formulas add a flat amount per inch, and because a range describes a population rather than a point. At 175 cm the 18.5 to 24.9 band spans nearly 20 kg — a fair measure of how loosely the word ideal is really known.
Does it work for people under five feet?
It calculates, and it warns you. Below 152 cm every one of these formulas runs backwards from its own starting point, subtracting per inch rather than adding, and none of them was derived or validated in that direction. The BMI range is the more defensible figure at short heights.
Is Ideal Weight Calculator really free, with no limits?
Yes. There is no account, no daily cap, no file-size tier and no watermark, because there is no server cost to recover. The site is funded by clearly disclosed partner recommendations on the Partners page, never by metering the tools.
Are my files or text uploaded when I use Ideal Weight Calculator?
No. Everything is processed by JavaScript running in your browser, on your device. You can verify it: open your browser's developer tools, switch to the Network tab, and use the tool. You will see no request carrying your data — because there is nowhere for it to go.