Finding Your Healthy Weight Range

"What should I weigh?" is best answered with a range rather than a number, and that range comes from inverting the BMI classification you already know.

Where the range comes from

BMI is weight divided by height squared. Rearranged, it gives weight for a given BMI:

weight = BMI × height(m)²

Evaluate that at the ends of the healthy BMI band and you have a healthy weight range:

low  = 18.5 × height(m)²
high = 24.9 × height(m)²

For someone 170 cm tall — so height² = 2.89:

18.5 × 2.89 = 53.5 kg
24.9 × 2.89 = 72.0 kg

A healthy weight range of 53.5 – 72.0 kg. Our Healthy Weight Range Calculator does this for any height, in metric or imperial.

No new evidence needed

This is worth noting because it is unusual: the calculator introduces no new source. It is a direct inversion of the WHO BMI classification, using the same cutoffs and the same citation as our BMI Calculator.

That is why it carries a high confidence rating. It inherits the evidence base of one of the most extensively population-validated screening measures in public health, rather than adding assumptions of its own.

It also inherits BMI's limitations, which matters — see below.

The range is wide on purpose

Nearly 20 kg separates the ends of that range, and that width is honest rather than vague. There is no single weight at which health switches on. The healthy band describes a region where population-level risk tends to be lower, with soft edges.

This is exactly why a range is a better answer than the single figure an ideal weight formula produces — see ideal weight vs healthy weight range for the direct comparison.

Why India shows different numbers

On our India pages the upper bound is lower. For the same 170 cm person:

The lower bound is unchanged, because the underweight threshold of 18.5 is the same on both scales. The upper bound drops because the normal band tops out at 22.9 rather than 24.9 under the WHO Asian cutoffs — why India uses different BMI cutoffs covers the reasoning.

The limitation it inherits

Because it is BMI inverted, it cannot see body composition. A muscular person can sit above the range without excess body fat, exactly as they read high on BMI itself — see BMI, muscle, and why athletes read high.

If your weight sits outside the range and you train seriously, check body fat or waist-to-height ratio before drawing conclusions. Those measures see what this one cannot.

The bottom line

Multiply your height in metres squared by 18.5 and 24.9 for a healthy weight range — 53.5 to 72.0 kg at 170 cm, or up to 66.2 kg under the WHO Asian cutoffs. It is BMI inverted, so it carries BMI's strong evidence base and BMI's blind spot for muscle. Find yours on the Healthy Weight Range Calculator.