For educational purposes only. Not personalised health advice. This calculator has not been reviewed by a registered dietitian, physician or exercise physiologist. Results are population estimates and can be wrong for you individually. Speak to a qualified professional before acting on them, particularly if you are pregnant, under 18, managing a medical condition, or have a history of disordered eating.
Ideal Weight Calculator
The concept of an "ideal body weight" emerged from the insurance and pharmaceutical industries, where researchers needed simple height-based reference weights for drug dosing and actuarial tables. Four formulas are in common use today: Hamwi (1964), Devine (1974), Robinson (1983), and Miller (1983). Each was developed independently and uses the same two inputs, height and biological sex, to produce slightly different results. Because they do not account for frame size, muscle mass, or body composition, no single formula defines an objective target for individual health. Instead, the range they collectively produce gives a useful statistical reference. If your current weight falls within or near the range across all four formulas, you are likely within normal population parameters for your height. This calculator shows results from all four formulas side by side so you can see where the consensus lies and how much variation exists. Enter your height in centimetres and your biological sex to see the comparison.
Formulas
inches_over_5ft = (height_cm - 152.4) / 2.54
Hamwi (male): 48.0 + 2.7 * inches_over_5ft
Hamwi (female): 45.5 + 2.2 * inches_over_5ft
Devine (male): 50.0 + 2.3 * inches_over_5ft
Devine (female): 45.5 + 2.3 * inches_over_5ft
Robinson (male): 52.0 + 1.9 * inches_over_5ft
Robinson (female): 49.0 + 1.7 * inches_over_5ft
Miller (male): 56.2 + 1.41 * inches_over_5ft
Miller (female): 53.1 + 1.36 * inches_over_5ft
Why the 'ideal weight' formulas disagree
If several ideal-weight formulas give you different answers, that is expected: they were built for different purposes and eras. The Devine formula (1974) was designed to standardise medication dosing, not to define health. Robinson, Miller and Hamwi each retuned the same basic idea for a different clinical use. None was meant to be the one true target, which is why a healthy weight is best read as a range, not a point.
All of these classic formulas share two blind spots. They key almost entirely off height and sex, so they cannot account for frame size, muscularity or body composition, and they were derived largely from mid-20th-century populations that do not represent everyone. A powerlifter and a sedentary person of the same height get the same 'ideal' figure, which is obviously wrong for at least one of them.
Treat the output as a reasonableness check rather than a goal to hit. If your weight sits well outside every formula's range, that is worth a conversation with a clinician. If it sits inside the spread they produce, the exact number matters far less than your waist measurement, fitness and how you feel and function day to day.
Ideal Weight Calculator: frequently asked questions
Which ideal weight formula is the most accurate?
No single formula is universally accurate. The Hamwi formula (1964) is widely used clinically for medication dosing. Devine (1974) became popular in pharmacokinetics. Robinson (1983) and Miller (1983) were developed as refinements. Each formula produces slightly different results and all are approximations. BMI and body composition measurements provide more personalised context.
Do these formulas account for muscle mass?
No. All four formulas are based solely on height and sex. A heavily muscled person may weigh well above the formula result yet have low body fat. These figures are statistical reference points developed for population-level drug dosing, not individual fitness targets.
What is the Hamwi formula?
The Hamwi formula gives male ideal weight as 48 kg for 152.4 cm (5 ft) plus 2.7 kg per additional 2.54 cm (1 inch) of height. For females it is 45.5 kg for 152.4 cm plus 2.2 kg per additional inch. It was developed by Dr George Hamwi in 1964.
Should I aim to weigh my ideal weight?
Not necessarily. These formulas give a reference range rather than a personal goal. Health is influenced by body composition, fitness level, metabolic markers, and many other factors beyond scale weight. Consult a doctor or registered dietitian to set a healthy personal weight goal.
What if my height is below 152.4 cm (5 ft)?
The original Hamwi and Devine formulas were designed for heights at or above 152.4 cm. For shorter heights the formulas are extrapolated by subtracting per-inch increments below 5 ft. This calculator applies that extrapolation but results for heights well below 5 ft should be interpreted with extra caution.
Official sources
- Hamwi GJ. (1964). "Therapy: Changing dietary concepts." Diabetes Mellitus: Diagnosis and Treatment, Vol 1.
- Devine BJ. (1974). "Gentamicin therapy." Drug Intelligence and Clinical Pharmacy, 8:650-655.
- Robinson JD, et al. (1983). "Determination of ideal body weight." American Journal of Hospital Pharmacy, 40:1016-1019.
- Miller DR, et al. (1983). "Identification of ideal body weight." American Journal of Hospital Pharmacy, 40:719-724.
This content is provided for educational purposes only and has not been reviewed by a qualified specialist in this field. See our methodology.