Ideal Weight Calculator - Robinson, Miller, Devine & Hamwi

See your ideal body weight according to four classic formulas plus the healthy BMI range, in both kg and lb. Free and runs entirely in your browser.

Sex

Average of four formulas

72.5 kg

160 lb

Formulakglb
Robinson (1983)71.1157
Miller (1983)70.4155
Devine (1974)73.2161
Hamwi (1964)75.2166
Healthy BMI range (18.5 - 24.9)58.6 - 78.9129 - 174

This is an indication, not medical advice.

Where These Ideal Weight Formulas Come From

None of the classic ideal body weight formulas started life as health advice. Hamwi (1964) was a quick bedside rule for estimating a starting point in diabetes care. Devine (1974) was created to dose drugs like gentamicin whose distribution follows lean mass rather than total weight; it is still the standard in clinical pharmacy today. Robinson and Miller (both 1983) are statistical refinements of Devine fitted against Metropolitan Life insurance mortality tables. All four share the same structure: a base weight at 5 feet plus a fixed increment per inch of height above that.

The formulas disagree with each other by design. For a 178 cm (5 ft 10 in) man, Robinson gives 71.1 kg, Miller 70.4 kg, Devine 73.2 kg, and Hamwi 75.2 kg, a spread of nearly 5 kg for the same person. Devine and Hamwi climb fastest with height (2.3 and 2.7 kg per inch), so they diverge most for tall people and produce unrealistically low numbers for very short people. That spread is exactly why this calculator shows all four plus their average rather than picking a single winner.

The healthy BMI range is the more useful benchmark for actual health. The WHO defines a healthy body mass index as 18.5 to 24.9, which for 178 cm translates to roughly 58.6 to 78.9 kg, a 20 kg wide window. That width is honest: bodies with different bone structure, muscle mass, and fat distribution can all be healthy at the same height. Note that BMI-based ranges are the same for men and women, while the four formulas build in a sex difference of a few kilograms.

Use these numbers as orientation, not as a target to chase. A muscular person can sit above every formula and the BMI range while being metabolically healthier than someone in the middle of it. Waist circumference, body fat percentage, blood pressure, and fitness say far more about health than scale weight. For a fuller picture, combine this tool with the BMI Calculator and the Body Fat Calculator, and set calorie targets with the Macro Calculator if you decide to change your weight.

How the Ideal Weight Calculator Works

  1. 01Select your sex and enter your height in cm or feet and inches.
  2. 02The tool computes ideal weight per Robinson (1983), Miller (1983), Devine (1974), and Hamwi (1964).
  3. 03It also shows the WHO healthy BMI range of 18.5 to 24.9 for your height.
  4. 04All results appear in both kilograms and pounds, with the four-formula average highlighted.

Reading the Results

Each formula uses a base weight at 5 feet plus a fixed number of kilograms per inch of height above that, which is why they diverge for tall and short people. For a 178 cm man the spread runs from about 70 kg (Miller) to 75 kg (Hamwi). The healthy BMI band is deliberately wide, about 20 kg for average heights, because healthy bodies vary in frame and muscle. If the formulas and the BMI band point to a similar zone, that zone is a reasonable orientation; your own waist, body fat, and fitness say more than any single number.

When to Use This Calculator

Use it for orientation when setting a long-term weight goal, for example after deciding to lose or gain weight, so your target lands inside a defensible range rather than a random number. It is also the formula set clinicians use: Devine ideal body weight underlies dosing of several medications and ventilator tidal volume settings. Do not use it as a daily judgment tool; weight fluctuates and frames differ.

Common Use Cases

  • Set a defensible long-term target before starting a weight loss plan → BMI Calculator
  • Check how your current weight compares to the healthy BMI range for your height
  • Convert formula results between kg and lb for a US or European audience → Weight Converter

Tips

  • Aim for a zone, not a single number; anywhere inside the healthy BMI band can be a legitimate goal.
  • Judge progress by trend weight (weekly average), waist measurement, and how clothes fit, not daily scale readings.
  • If you train with weights, expect to land above the formula values while getting leaner; that is muscle, not failure.

Frequently Asked Questions

Why do the four formulas disagree?→
They were built decades apart for different purposes: Hamwi (1964) as a bedside rule, Devine (1974) for drug dosing, and Robinson and Miller (1983) as statistical refinements against insurance mortality tables. Their per-inch increments range from 1.36 to 2.7 kg, so the gap grows with height and can reach 5 kg or more.
Which formula should I trust?→
None individually; use the average and the healthy BMI range together. Devine remains the clinical standard for medication dosing, but for personal goal setting the WHO BMI band of 18.5-24.9 is the better anchor because it defines a range rather than one number.
Is the ideal weight different for men and women?→
In the four formulas, yes: the female versions start 2-7 kg lower at the same height, reflecting average differences in frame and muscle. The BMI-based healthy range is identical for both sexes, which is one of its known simplifications.
I am muscular and weigh more than every formula says. Is that a problem?→
Not by itself. The formulas and BMI cannot distinguish muscle from fat, and a muscular person can exceed all of them while being metabolically healthy. Body fat percentage and waist circumference are far better indicators in that case.
How fast should I move toward an ideal weight?→
A sustainable rate is about 0.5 kg per week, which corresponds to a 500 kcal daily deficit. Faster loss increases muscle loss and rebound risk. If your target is 10 kg away, plan for roughly five months, not five weeks.

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