Ideal Weight Calculator
Estimate your ideal body weight using four widely used medical formulas.
The ideal weight calculator applies four classic medical formulas to estimate a healthy weight for your height. Because body frame, muscle mass and age differ, each formula gives a slightly different answer — the average is a useful middle ground.
How to use the calculator
- Select your gender.
- Enter your height in centimetres.
- Compare the four formula results and the average.
- Treat the figure as a range, not a strict target.
How it is calculated
Robinson, Miller and Hamwi use the same structure with different coefficients.
Worked example
Male, 170 cm (about 5 ft 7 in)
Devine ≈ 65.9 kg, Robinson ≈ 65.2 kg, Miller ≈ 66.0 kg
Average ideal weight ≈ 65.9 kg.
Who should use this calculator
- Anyone setting a target weight after a weight-loss programme, so the goal is reachable rather than arbitrary.
- People recovering from an eating disorder or a long illness, in discussion with their doctor, who need a healthy range rather than a single figure.
- Anyone curious about how clinicians estimate weight for medication dosing.
- People who have reached a target weight and want to know how much fluctuation is normal.
Common mistakes to avoid
- Treating one formula as the answer. Devine, Robinson, Miller and Hamwi use different coefficients and can disagree by several kilograms for the same height. The average is more useful than any single value.
- Ignoring build and muscle. These formulas say nothing about frame size or lean mass. A broad-shouldered, muscular person can be perfectly healthy above the estimated figure.
- Chasing an exact number. A healthy weight is a range of three to five kilograms, not a decimal point on a scale.
- Forgetting age. Slightly higher weight is often healthier after 65 because it protects muscle and bone. Very low body weight in older adults is linked to frailty.
- Comparing with someone else. Two people of the same height can have very different healthy weights depending on build, and neither is wrong.
Why the four formulas disagree
Each formula was derived from a different population, for a different purpose. Devine was created for drug dosing, Robinson and Miller refined the coefficients, and Hamwi is widely used in nutrition. For a man of 170 cm they produce roughly 65.9 kg, 65.2 kg, 66.0 kg and 66.7 kg — close, but not identical.
That spread is the point: there is no single correct weight for a height. The BMI-derived healthy range for the same person, about 53.5 kg to 72 kg, is wider still. Aim to sit comfortably inside that range with a waist measurement in a healthy zone, rather than hitting a specific number by a specific date.
Ideal weight terms explained
- Devine formula
- The most widely used clinical estimate, based on 50 kg for men and 45.5 kg for women at 5 feet, plus a fixed amount per additional inch.
- Healthy BMI range
- The weight range that corresponds to a BMI between 18.5 and 24.9 for your height.
- Body frame
- Skeletal build, usually judged by wrist circumference. Larger frames carry more weight at the same body fat.
- Lean mass
- Muscle, bone and organ tissue. Higher lean mass means a healthy weight can be above the estimate.
- Target range
- A band of a few kilograms around the estimate. Staying inside it is more realistic than holding one exact weight.
Setting a target you can actually hold
The most useful target is one you can maintain without monitoring every meal. Pick a band — say three kilograms — and treat anywhere inside it as success rather than chasing the bottom of the range. Judge progress by waist measurement, energy levels and how clothes fit alongside the scale. If holding a weight requires permanent hunger or daily weighing, the target is probably too low for your build, and a slightly higher weight that you can sustain is the better outcome for your health.
Frequently asked questions
Which ideal weight formula is best?
None is definitive. Devine is the most used clinically, Robinson and Miller tend to give slightly lower figures, and Hamwi is popular in nutrition. Averaging them, or using a BMI-based healthy range, gives a more realistic view.
Should I aim for my ideal weight exactly?
No. A healthy range of 3–5 kg around the estimate is perfectly fine, and body composition matters more than the number on the scale. Focus on waist size, strength and energy levels.
Does ideal weight change with age?
Yes. Slightly higher weight is often healthier in older age, because it preserves muscle and bone. Very low body weight in the elderly is linked with frailty, so strict ideal-weight targets are less useful after 65.