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"Ideal" weight formulas are rough population averages: the healthy BMI range is a better guide than any single number, and muscle mass, frame and ethnicity all shift what is healthy for an individual. Not medical advice; discuss weight goals with your GP or practice nurse.
What The Ideal Weight Calculator Works Out
- Healthy BMI weight range: the weights that give a BMI of 18.5 to 25 at your height (BMI x height in metres squared). For a 175 cm man that spans 56.7 to 76.6 kg, and that twenty-kilogram spread is the honest answer: healthy weight is a range, and single-number "ideals" are precision without accuracy. The NHS uses BMI ranges rather than ideal-weight formulas.
- Devine formula: 50 kg for men or 45.5 kg for women plus 2.3 kg per inch over five feet, giving 70.5 kg for a 175 cm man. It was published in 1974 for scaling drug doses, not for judging bodies, and still underpins drug dosing, ventilator tidal volumes and some nutrition calculations.
- In stones and pounds: the range and the Devine figure in imperial units, since most UK bathroom scales still talk in stones.
- Height in feet and inches (advanced): enter height imperially and it overrides the cm box.
- Ethnic background (advanced): the NHS applies lower BMI thresholds (23 for overweight, 27.5 for obese) for people of South Asian, Chinese, Black African or Caribbean background, where health risks start at lower BMI. Choosing this narrows the healthy range and shifts the table.
- Robinson, Miller and Hamwi (advanced): Devine's cousins shuffle the same coefficients: Robinson (1983) 52 kg + 1.9 kg per inch for men, Miller (1983) 56.2 kg + 1.41 kg per inch, and Hamwi (1964) 48 kg + 2.7 kg per inch. Seeing them side by side shows how arbitrary any single figure is.
- Personal target BMI (advanced): the weight at any BMI you choose, for example 22 as a comfortable midpoint or 24 for a muscular build. BMI misreads muscular builds as heavy and misses low muscle mass in older people, so waist-to-height ratio under 0.5 is a useful companion check.
- Your current weight (advanced): in kg, stones or pounds, giving your current BMI and how far you sit from the healthy range. For those above it, a modest sustained loss of 5% to 10% delivers most of the measurable health improvement, so the card shows that target too; the timescale assumes 0.5 kg a week.
- BMI table (advanced): the weights at your height for each BMI landmark from 18.5 to 35. Trajectory beats target: habits that survive contact with real life outperform any number chosen from a formula. Not medical advice; a GP or practice nurse can put any of these numbers in personal context.
Source and further reading: NHS: BMI and healthy weight.