Ideal Weight Calculator
What should you weigh? Doctors do not have one answer — they have four. The Devine, Robinson, Miller and Hamwi formulas are the classic medical formulas for estimating a healthy weight from height and sex, and each gives a slightly different number. This free calculator runs all four at once and shows you the full ideal weight range for your height.
Ideal Weight Calculator
How to Use This Calculator
Choose your sex and your preferred units — metric or imperial. The calculator shows the right height fields and converts your values automatically if you switch units halfway through.
Enter your height. If you do not know it exactly, have someone measure you against a wall: stand flat-footed with a book on your head, mark the wall, and measure from the floor to the mark.
Click Calculate. You will see the ideal weight from each of the four formulas plus the overall range they span, along with the healthy BMI range (18.5–24.9) for your height so you can compare the two approaches. Click Reset to start over.
The Formula
All four formulas share the same shape: they start from a base weight for a 5-foot-tall (60-inch) person and add a fixed amount for every inch above 5 feet. Let "over" be your height in inches minus 60:
Devine: men 50 + 2.3 × over kg; women 45.5 + 2.3 × over kg. Robinson: men 52 + 1.9 × over kg; women 49 + 1.7 × over kg. Miller: men 56.2 + 1.41 × over kg; women 53.1 + 1.36 × over kg. Hamwi: men 48 + 2.7 × over kg; women 45.5 + 2.2 × over kg.
Worked example: a man who is 170 cm tall. That is 170 ÷ 2.54 = 66.9 inches, or 6.9 inches above the 60-inch baseline. Devine: 50 + 2.3 × 6.9 ≈ 65.9 kg. Robinson: 52 + 1.9 × 6.9 ≈ 65.1 kg. Miller: 56.2 + 1.41 × 6.9 ≈ 65.9 kg. Hamwi: 48 + 2.7 × 6.9 ≈ 66.6 kg. The four formulas span roughly 65 to 67 kg — about 144 to 147 lbs — which is why the calculator reports a range rather than a single number.
Tips
Treat the range as a planning target, not a pass-or-fail test. Frame size, muscle mass and genetics all shift where your healthiest weight sits, so anywhere inside the range is a reasonable goal — what matters is that your trend is moving toward it.
Use ideal weight alongside other numbers. If your BMI is in the healthy band, your body fat is in a healthy range, and you have energy for daily life, you are very likely at a good weight even if you sit at the edge of a formula's range.
Muscle changes the picture. The formulas assume an average build, so a regular lifter will often land above the formula weight while staying lean — in that case body fat percentage and waist measurement are better gauges than an ideal weight formula.
Frequently Asked Questions
What is an ideal body weight?
An ideal body weight is a medically estimated weight associated with the lowest health risk for a person of a given height and sex. It is a reference point for setting realistic goals, not a strict target — healthy bodies come in many shapes and sizes.
Which ideal weight formula is the most accurate?
None is universally the most accurate. The formulas were derived from different patient groups and insurance data between the 1950s and 1980s. Devine and Hamwi are the most widely used in clinical practice, while Robinson and Miller tend to give slightly lower values. That is why this calculator shows the range across all four.
Does ideal weight change with age?
There is some evidence that the healthiest weight drifts upward slightly in later decades, mainly because body composition changes and muscle mass declines. The classic formulas do not adjust for age, though. Rather than gaining weight with age, focus on preserving muscle with strength training.
Why is ideal weight a range and not one number?
Because the four accepted formulas make different assumptions about the height-weight relationship, they give slightly different answers. A range also reflects reality: people with different frame sizes and amounts of muscle are healthy at different weights, and no single number fits everyone.
Does muscle affect my ideal weight?
Yes. The formulas assume an average build, so a muscular person can be above their formula weight while staying lean and healthy. If you lift weights regularly, body fat percentage and waist measurement are better gauges of health than an ideal weight formula.