Ideal weight formulas have been around for decades — but they're all imperfect approximations. Here's what the main formulas say, what a healthier target looks like, and why the number matters less than you think.
The quest for an "ideal weight" is one of the most searched health questions online. The honest answer is that ideal weight isn't a single number — it's a range, it varies by frame and muscle mass, and for most people, a 5–10kg range is more useful than a single target.
Several formulas have been developed over the decades, originally for clinical drug dosing. They produce different answers — none is definitively correct.
Four widely used formulas produce a 3.4kg spread for the same person. This illustrates why treating any single formula's output as a definitive target is misguided.
A common alternative: find the weight that puts you at the centre of the healthy BMI range (18.5–24.9). The midpoint is around BMI 21.7.
For the same person, the healthy BMI range spans nearly 20kg — from 56.7kg to 76.3kg. Any weight within that range is "healthy" by BMI criteria.
All ideal weight formulas — and BMI — are based on averages that assume a typical ratio of fat to lean mass. They systematically misclassify:
Body fat percentage is a more meaningful target than weight alone. For most people, a healthy body fat percentage (roughly 18–24% for men, 25–31% for women) combined with being in a healthy BMI range is more informative than any single number.
Rather than targeting a specific weight, most sports scientists and dietitians recommend targeting:
These targets account for individual variation in a way that a formula number cannot. The ideal weight calculator gives you a useful reference range — but your body composition, energy levels, and health markers tell the fuller story.