“What should I weigh?” is one of the most searched health questions, and four decades of research have produced several simple formulas that answer it with a single number for each height. This calculator applies the four best known, shows them side by side, and sets them against the weight range that corresponds to a BMI of 18.5 to 24.9, so you can see both the traditional figure and the band that the World Health Organization calls healthy.
None of these numbers is a goal you must reach. They are reference values. Your own healthy weight depends on build, muscle, age and health, which formulas cannot see.
How to use the ideal weight calculator
- Select your sex. The formulas use different base weights for men and women.
- Enter your height in centimetres, inches, feet or metres.
- Compare the four formulas. Look at the spread between them rather than any single value.
- Check the BMI-based range. If your weight falls inside it, you are in the WHO normal range.
Ideal weight formulas
In each formula, H is the number of inches over 5 feet (60 inches), and the result is in kilograms.
Robinson (1983): men 52 + 1.9 × H · women 49 + 1.7 × H
Miller (1983): men 56.2 + 1.41 × H · women 53.1 + 1.36 × H
Hamwi (1964): men 48 + 2.7 × H · women 45.5 + 2.2 × H
Healthy range = 18.5 × height² to 24.9 × height² (height in metres)
Hamwi’s rule comes from Hamwi GJ, Therapy: changing dietary concepts, in Diabetes Mellitus: Diagnosis and Treatment (American Diabetes Association, 1964). Devine is from Drug Intelligence and Clinical Pharmacy 1974;8:650–655. Robinson and Miller appeared in the American Journal of Hospital Pharmacy 1983;40:1016 and 1983;40:1622. Pai and Paloucek compared them in Annals of Pharmacotherapy 2000;34:1066–1069. The BMI range follows WHO Technical Report 894.
Worked example
A man who is 5 ft 10 in (70 in, 177.8 cm).
- H = 70 − 60 = 10 inches over 5 feet.
- Devine: 50 + 2.3 × 10 = 73.0 kg
- Robinson: 52 + 1.9 × 10 = 71.0 kg
- Miller: 56.2 + 1.41 × 10 = 70.3 kg
- Hamwi: 48 + 2.7 × 10 = 75.0 kg
- Average of the four: 72.3 kg (159 lb). BMI 18.5–24.9 at 1.778 m is 58.5–78.7 kg.
Devine weights and the healthy BMI range by height
| Height | Devine, women (kg) | Devine, men (kg) | WHO healthy BMI range, both (kg) |
|---|---|---|---|
| 5′0″ (152 cm) | 45.5 | 50.0 | 43.0 – 57.8 |
| 5′2″ (157 cm) | 50.1 | 54.6 | 45.9 – 61.8 |
| 5′4″ (163 cm) | 54.7 | 59.2 | 48.9 – 65.8 |
| 5′6″ (168 cm) | 59.3 | 63.8 | 52.0 – 70.0 |
| 5′8″ (173 cm) | 63.9 | 68.4 | 55.2 – 74.3 |
| 5′10″ (178 cm) | 68.5 | 73.0 | 58.5 – 78.7 |
| 6′0″ (183 cm) | 73.1 | 77.6 | 61.9 – 83.3 |
| 6′2″ (188 cm) | 77.7 | 82.2 | 65.4 – 88.0 |
| 6′4″ (193 cm) | 82.3 | 86.8 | 68.9 – 92.8 |
Where the formulas came from
Ideal weight formulas were written for clinical convenience. Hamwi’s rule of thumb gave dietitians a quick starting point for diabetes diets. Devine adapted it to estimate how much of a drug a patient would need, and the later Robinson and Miller equations were attempts to fit data from larger groups. None was developed to say what the healthiest weight is, and none accounts for frame size, ethnic background or body composition.
Using the result well
- Prefer ranges to single numbers. The healthy BMI band spans around 17 kg at 165 cm.
- Look beyond the scale. Waist size and body fat tell you about distribution; see the Waist-to-Height Ratio Calculator and Body Fat Calculator.
- For medical dosing, ask a clinician. Prescribers sometimes use adjusted weights in obesity; see the Adjusted Body Weight Calculator.
- Set goals with a professional if you need to change weight for health reasons.
For a range-based view try the Healthy Weight Range Calculator; to check your BMI use the BMI Calculator.
This page is for information only and is not medical or dietary advice. Speak to a doctor or registered dietitian before making large changes to your diet or exercise.
Sources
- Devine BJ. Gentamicin therapy. Drug Intelligence and Clinical Pharmacy 1974;8:650–655.
- Robinson JD, et al. Determining ideal body weight. Am J Hosp Pharm 1983;40:1016–1019.
- Miller DR, et al. Determining ideal body weight. Am J Hosp Pharm 1983;40:1622–1623.
- Hamwi GJ. Therapy: changing dietary concepts. In: Diabetes Mellitus: Diagnosis and Treatment. American Diabetes Association, 1964;1:73–78.
- Pai MP, Paloucek FP. The origin of the “ideal” body weight equations. Ann Pharmacother 2000;34:1066–1069.
- World Health Organization. Obesity: preventing and managing the global epidemic. WHO Technical Report Series 894, 2000.
Frequently asked questions
What is ideal body weight?
Ideal body weight (IBW) is an estimate of the weight expected for a person of a given height and sex, derived from simple formulas. The Devine formula was written in 1974 to help dose medicines, not to define a healthy weight, which is why it is better treated as a reference than as a target.
Why do the formulas give different answers?
Each was built from different data and for a different purpose. Hamwi (1964) came from insurance tables, Devine (1974) was proposed for drug dosing, and Robinson and Miller (both 1983) were revisions to fit later population data. Differences of a few kilograms are normal.
Is the ideal weight the same as a healthy weight?
Not exactly. The healthy weight range based on BMI (18.5 to 24.9) is a band of several kilograms, while an ideal-weight formula returns a single number. If your weight lies inside the BMI band and you are well, you do not need to hit a formula figure.
Do these formulas work for short people and children?
The formulas start at 5 feet (60 inches), so results for heights below that are extrapolations and become unreliable. They are for adults only; children’s weights are judged on growth charts.
What about muscular people or older adults?
Formulas ignore body composition. An athlete can weigh more than the formula and still be lean, and an older adult with low muscle can weigh the formula figure with a high fat share. A body-fat estimate or waist measurement gives more information.