Ideal weight calculator
Enter your height to compare five classic ideal weight formulas with the weights that match a normal BMI. They are rough guides, not targets.
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About you
Ideal weight by formula
The formulas give
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Choose the sex used by the formulas, then enter your height.
- Normal BMI range (WHO)
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Result of each formula
- Devine (1974) — Not for this height
- Robinson (1983) — Not for this height
- Miller (1983) — Not for this height
- Hamwi (1964) — Not for this height
- Lorentz (1929) — Not for this height
- Normal BMI (WHO) — 18.5 to 24.9 × height (m)²
Each dot is one formula, on the same scale. The shaded band is the normal BMI range for this height.
Devine, Robinson, Miller and Hamwi add weight for each inch over 5 ft (152.4 cm), so they say nothing about shorter heights. Lorentz corrects for the height above 150 cm, so it’s used from 150 cm.
Formulas: Hamwi (1964), Devine (1974), Robinson (1983), Miller (1983), Lorentz (1929). Normal range: World Health Organization (WHO), BMI 18.5 to 24.9 for adults.
Why these are only rough guides
- Old benchmarks. Lorentz dates from 1929 and Hamwi from 1964. Devine published his in 1974 to work out medicine doses, and Robinson and Miller proposed revised versions in 1983.
- Height and sex only. They ignore age, muscle, build and where fat is stored.
- No single right number. The formulas disagree with each other by several kilograms, and none of them is a weight you have to reach.
- Short and very tall heights. Four of the formulas only start at 5 ft (152.4 cm), and all of them mean less at the extremes.
- Children, teenagers and pregnancy. These formulas don’t apply.
These figures are general information, not medical advice or a weight to aim for. If you have questions about your weight, talk to a doctor.
How it works
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Choose your units and sex
Kilograms and centimetres, or pounds, feet and inches. Each formula has one version for women and one for men.
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Enter your height
The five formulas and the normal BMI range update as you type.
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Compare the results
Each dot shows one formula on the same scale, and the shaded band is the normal BMI range for your height.
Frequently asked questions
What is the ideal weight for my height?
There is no single ideal weight. The classic formulas each give one figure from your height and sex, and they disagree by several kilograms. For a man who is 175 cm (5 ft 9 in) tall, they range from 68.7 kg (Miller) to 72.0 kg (Hamwi), while the WHO normal BMI range for that height goes from 56.7 to 76.3 kg. Body shape, muscle and health matter as much as the number.
Which ideal weight formula is the most accurate?
None of them is accurate for one person: they are simple straight-line rules from another era. Devine’s formula (1974) is still widely used in medicine, for example to work out some medicine doses. Robinson and Miller revised it in 1983, Hamwi’s dates from 1964, and Lorentz’s (1929) remains common in France. Comparing them shows how much they differ.
What are the formulas?
Per inch over 5 ft (152.4 cm). Devine: men 50 kg + 2.3 kg, women 45.5 kg + 2.3 kg. Robinson: men 52 kg + 1.9 kg, women 49 kg + 1.7 kg. Miller: men 56.2 kg + 1.41 kg, women 53.1 kg + 1.36 kg. Hamwi: men 48 kg + 2.7 kg, women 45.5 kg + 2.2 kg (first published as 106 lb + 6 lb and 100 lb + 5 lb). Lorentz: height (cm) − 100 − (height − 150) ÷ 4 for men, ÷ 2.5 for women. Normal BMI range: 18.5 to 24.9 × height (m)². Sources: Devine, Drug Intelligence and Clinical Pharmacy (1974); Robinson and Miller, American Journal of Hospital Pharmacy (1983); Hamwi, American Diabetes Association (1964); Lorentz, Klinische Wochenschrift (1929); WHO for BMI.
Why are some formulas missing for my height?
Devine, Robinson, Miller and Hamwi start at 5 ft (152.4 cm) and add weight for each inch above it, so they say nothing about shorter heights. Lorentz corrects for the height above 150 cm, so the calculator uses it from 150 cm. The normal BMI range works at any adult height.
Can I use it for a child or during pregnancy?
No. These formulas are for adults. Under 18, weight is read on growth charts by age and sex, and during pregnancy, weight gain follows its own guidance. A doctor or a midwife can help.
Is my height stored?
No. The calculation runs in your browser and nothing you type is sent anywhere. Only your choice of units is remembered on this device.