What Is "Ideal Weight," Really?
Ideal weight is a population-level estimate of a healthy target weight for a given height, originally created for practical clinical purposes such as calculating medication dosages. It is not a single perfect number your body must hit — it's a reasonable, evidence-informed anchor point that you can use alongside other measurements like body fat percentage and waist circumference to judge whether your current weight fits a healthy range.
The Devine Formula
This calculator uses the Devine formula, first published in 1974 and still one of the most common formulas used in medicine today, particularly for calculating drug dosing in hospitals. For men, it starts at 50 kg for the first five feet of height and adds 2.3 kg for every inch above that; for women it starts at 45.5 kg with the same 2.3 kg per inch. The formula deliberately keeps things simple — height and sex only — which is exactly why it has remained in clinical use for half a century despite newer, more complex alternatives.
Why We Also Show a BMI-Based Range
Because a single number can feel unforgiving, this tool also shows the full healthy weight range implied by a BMI between 18.5 and 24.9 at your height. This range is typically wider than the single Devine figure and gives you room to think in terms of a target zone rather than one exact digit on the scale. Comparing both numbers side by side also highlights how the Devine formula and BMI-based ranges can diverge slightly, especially at height extremes, reinforcing that neither method should be treated as an absolute rule.
Factors These Formulas Don't Capture
No height-based formula accounts for muscle mass, bone density, age, or frame size. A muscular person will comfortably weigh more than their "ideal weight" while carrying very little body fat, and an older adult with reduced muscle mass may sit at their ideal weight number while still carrying more fat than is healthy. Frame size matters too — someone with a naturally broad skeletal structure will carry more healthy weight than someone with a narrow frame at the same height. That's why we built a dedicated Body Type Calculator to estimate frame size, and a Body Fat Percentage Calculator to look at composition directly rather than weight alone.
How To Use This Number Sensibly
Use your ideal weight and BMI range as a general compass rather than a strict target. If you're an athlete, older adult, pregnant, or recovering from illness, these formulas are far less reliable and you should lean more heavily on guidance from a healthcare provider. For most healthy adults without extreme muscularity, the range shown here is a reasonable, well-established target zone that has guided medical practice for decades.
A Quick Tip Before You Weigh In
If your result feels lower or higher than expected, remember that the Devine formula was built from a general adult population and doesn't know your training history. Someone who has spent years lifting weights will typically sit above this number while still being lean and healthy, so use it as one data point among several rather than a strict target to chase on the scale.
Frequently Asked Questions
Is the Devine formula the same for men and women?
No — women's ideal weight is calculated from a lower base (45.5 kg vs 50 kg for men) before the same per-inch addition is applied.
Why is there a range instead of one number?
A single number ignores natural variation in frame size and muscle mass, so we also show the wider healthy-BMI range for more realistic context.
Does this formula work for very short or very tall people?
It's reasonably reliable across typical adult heights, but becomes less precise at extreme heights, where individual frame variation matters more.
Should athletes use this number?
Muscular athletes will often weigh above their calculated ideal weight while remaining perfectly healthy — body fat percentage is a better guide for them.