UK Ideal Weight Calculator

Ideal weight calculators have been around for decades, using a handful of different formulas that all try to answer the same broad question: what is a reasonable weight range for someone of a given height. None of them is perfectly precise, but seeing a few side by side gives a more balanced picture than trusting a single number.

The term “ideal weight” is a bit misleading, since there is no single perfect figure for anyone. These formulas are best used as general reference points alongside other measures, not as a strict target.

This calculator shows estimates from the Devine and Robinson formulas alongside the NHS healthy BMI range, so you can see where they agree and where they differ.

How to use the ideal weight calculator

Enter your gender and height, in metric or imperial units. You can optionally choose a body frame size, small, medium or large, as a rough refinement. The calculator shows estimates from the Devine and Robinson formulas, plus the NHS healthy weight range based on BMI.

Where these formulas come from

The Devine formula, published in 1974, was originally created for calculating medication dosages and became widely adopted more broadly. The Robinson formula, from 1983, is a later refinement using different data. Both estimate a baseline weight for five feet in height, then add a fixed amount for every inch above that. The NHS BMI range, by contrast, uses the well known Body Mass Index formula applied to the boundaries of the healthy 18.5 to 24.9 range.

Because the Devine and Robinson formulas were originally designed for clinical and pharmaceutical purposes rather than general public use, they tend to produce a single number rather than a range. This calculator pairs them with the NHS BMI range specifically to avoid the impression that either formula produces a precise target you should aim for.

Worked example

Take a man who is 180cm tall, with a medium body frame. The Devine formula estimates around 75.0kg. The Robinson formula estimates around 72.6kg. The NHS healthy BMI range for the same height spans roughly 59.9kg to 80.7kg, a considerably wider band than either single formula suggests on its own.

This is a good illustration of why it is more useful to think in terms of a healthy range rather than a single ideal number. All three estimates above sit comfortably within the NHS range, which is really the main takeaway: there is no single correct weight for a given height, only a broad range that is generally considered healthy.

Why these numbers should not be treated as targets

These formulas were developed decades ago using specific, often narrow, study populations, and none of them account for muscle mass, bone structure, or the ethnicity adjusted BMI thresholds the NHS uses for some groups. A very muscular person may sit above every figure shown here despite being perfectly healthy. Treat the results as general context rather than a number to aim for exactly, and remember that a healthy weight looks different for different people even at the same height.

If you have any concerns about your weight, in either direction, your GP is best placed to give advice that takes your full health picture into account, not just your height.

Frame size, an optional and imprecise adjustment

The body frame option in this calculator applies a rough percentage adjustment, smaller for a small frame and larger for a large frame, loosely reflecting the idea that two people of identical height can have genuinely different healthy weights depending on their bone structure. There is no single agreed clinical method for measuring frame size, so this adjustment is offered as an optional refinement rather than a precise calculation. Leaving it on the medium default is entirely reasonable if you are unsure.

Related calculators

For a single widely used measure, try our BMI calculator, and our BMI guide covers NHS categories and ethnicity adjusted thresholds in more depth. Our TDEE calculator covers general daily calorie needs if you want the fuller picture alongside a healthy weight range. Our age calculator and pregnancy due date calculator cover other everyday and life stage calculations you might find useful.