🎯 Ideal Weight

About this calculator

There is no single "perfect" weight, but several well-known formulas give a healthy reference range to work with. Enter your height, sex, and optionally your frame size, and this calculator shows your ideal weight according to the Robinson, Miller, Devine, and Hamwi formulas, plus the BMI-based healthy range. Seeing the spread across formulas keeps any single number in perspective instead of treating one figure as gospel.

Tip: use this as a starting point, not a verdict — muscle mass, build, and overall health matter far more than hitting one exact number.

How to read an ideal weight result

There is no single ideal weight for a height, which is why this calculator shows you several answers. The named formulas, Devine, Robinson, Miller and Hamwi, were built in the last century for jobs like setting drug doses and pricing insurance, not for judging health, and they disagree with each other by several kilograms for the same person. The BMI based range answers a different question: across large populations, weights between BMI 18.5 and 24.9 are associated with the lowest health risks, and at typical heights that band is 15 to 18 kg wide. That width is the honest part of the science. Where you sit best inside the range depends on muscle mass, waist size, age and history. Someone carrying good muscle at the top of the range with a slim waist is in a different position from someone at the same weight with little muscle and a large waist, and an older adult may be healthier keeping some reserves than chasing the weight they held at 20. Treat any single formula output as the middle of a neighbourhood, not a pass or fail line.

A worked example

Consider a woman who is 165 cm tall, which is 5 feet 5 inches. The Devine formula, the most widely used of the set, starts women at 45.5 kg for 5 feet and adds 2.3 kg for each additional inch, giving 45.5 plus 11.5, which is 57 kg. The other formulas cluster nearby in the high 50s. The BMI healthy range for her height, however, runs from 50 kg to 68 kg. So the formulas are pointing at the centre of a band that is 18 kg wide. If she currently weighs 70 kg, the formulas describe a gap of 13 kg, while the population health evidence says she is about 2 kg above the top of the range associated with lowest risk. Both statements are true, and the second is usually the more useful one for setting a first goal.

Common mistakes

• Taking one formula as a medical verdict. A 2 kg disagreement between formulas is normal, and neither knows anything about your build, muscle or health history.
• Applying these formulas where they were never meant to go: children and teenagers, pregnancy, competitive strength athletes, and people with amputations or conditions affecting body composition.
• Assuming frame size explains large differences. Traditional frame adjustments move the target by about 10 percent at most; they cannot reconcile a 20 kg gap.
• Setting the formula output as an all or nothing goal. Losing 5 to 10 percent of body weight already improves blood pressure, blood sugar and joint load, well before any formula is satisfied.
• Ignoring the waist. Two people at the identical height and weight can carry very different risk, and waist circumference separates them better than any ideal weight table.

Frequently asked questions

Why do the formulas give different ideal weights?

Because they were built by different people, for different jobs, decades apart. Devine's formula came from drug dosing, Hamwi's from a clinician's rule of thumb, and others from insurance data. Each rounded human variation into a simple line. Disagreements of 3 to 5 kg for the same height are normal.

Is the middle of the healthy BMI range the best target?

Not necessarily. The healthy range is wide precisely because risk changes gradually across it. People with more muscle often sit healthily near the top, while others feel and function best lower down. Blood pressure, blood sugar, waist size and fitness say more about your best position than the midpoint does.

Does frame size really change my ideal weight?

A little. Traditional frame adjustments, based loosely on wrist or elbow breadth, move formula targets by about 10 percent up or down. That can matter at the margins, but frame size cannot explain large gaps, and it is often used to justify numbers the evidence does not support.

What if my ideal weight feels unreachable?

Then aim at the evidence instead of the formula. Losing 5 to 10 percent of your current weight already delivers measurable improvements in blood pressure, blood sugar and joint pain. A weight you can maintain for years does more for your health than a lower one you visit briefly.