Use the free Ideal Body Weight Calculator below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
What This Calculator Does
An ideal body weight calculator estimates a healthy weight range from your height. It does not look at your body fat, your muscle, or your frame size. It answers a narrower question: for someone of your height, what weight did old medical formulas consider typical? Doctors once used these numbers to dose medicines and to judge whether a patient was underweight or overweight. Today they are best used as a rough reference point, not as a target you must hit. Your healthy weight depends on much more than height.
This tool shows two classic formulas side by side. The Devine formula starts at 50 kilograms for men and 45.5 kilograms for women at five feet tall, then adds 2.3 kilograms for each inch above five feet. The Robinson formula starts slightly higher, at 52 kilograms for men and 49 for women, with the same 2.3-kilogram step. For most heights the two answers are within a few kilograms of each other. The tool also shows a range about 10 percent above and below the Devine result, because healthy bodies naturally vary around any single number.
How to Use It
Choose your sex and type your height in centimetres. Click Calculate. You will see the Devine result, the Robinson result, and the range. If you are shorter than five feet, both formulas give their starting weight, because they were not designed to go below five feet. That is a limit of the formulas, not a statement about your body. Compare the range with your actual weight, but do not judge yourself by it alone. A muscular person can be healthy above the range, and a person with low muscle can be unhealthy inside it.
Where These Formulas Came From
Devine published his formula in 1974 to help doctors estimate drug doses. Robinson published a revised version in 1983. Both were built for adults of average build in an era when people were, on average, smaller than today. They ignore age, ethnicity, bone structure, and body composition. That is why modern health checks pair weight with other measures: waist size, body fat percentage, blood pressure, blood sugar, and fitness. A single height-based number cannot capture all of that. Use it as one data point among several.
A Worked Example
Take a woman who is 165 centimetres tall. That is about 65 inches, or five inches above five feet. Her Devine weight is 45.5 plus 5 times 2.3, which is 57 kilograms. Her Robinson weight is 49 plus 11.5, which is 60.5 kilograms. Her range around the Devine result is about 51.3 to 62.7 kilograms. If she weighs 58 kilograms and feels strong and energetic, the range supports that she is in a typical zone. If she weighs 75 kilograms but lifts weights four times a week, the range alone does not prove a problem, because muscle is heavy.
Common Mistakes
The biggest mistake is treating the result as a pass-or-fail test. Weight alone is a poor health score. Another mistake is chasing the middle of the range quickly with a crash diet. Fast weight loss often loses muscle and water, not just fat, and the weight usually returns. A better approach is slow change: eat slightly less or move a little more, keep protein up, and protect sleep. If your weight sits far outside the range and you also have low energy, breathlessness, or other symptoms, that combination is worth discussing with a doctor.
Frequently Asked Questions
Does ideal weight change with age? These formulas do not include age, but healthy weight often rises slightly with age as muscle patterns change. Older adults who lose weight without trying should seek medical advice. What about children and teenagers? These formulas are for adults only. Children use growth charts that compare them with peers of the same age and sex. Is BMI better? BMI also uses only height and weight, so it shares the same limits. It is useful for populations, less precise for individuals.
Educational estimate only. This is not medical advice. Talk to a health professional before starting a weight-loss or weight-gain plan, especially if you have a medical condition.
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