Which ideal weight formula is most accurate?

No single formula is universally accurate. The BMI-range method (18.5–24.9 applied to height) is the most evidence-based and gives a range rather than a single number. Hamwi and Devine are older clinical rules of thumb still used in pharmacy and medicine.

Why do the three formulas give different results?

Hamwi (1964) and Devine (1974) were derived from clinical populations and produce a single point estimate. The BMI-range method is derived from epidemiological data and is broader. Individual factors like muscle mass and frame size mean no formula is perfectly accurate for everyone.

Does ideal weight differ by body frame size?

Some clinicians add ±10% to ideal weight estimates for small or large frames. However, there is no standardised method for measuring frame size, so this adjustment is rarely used in practice.

Is my data sent to a server?

All calculations are pure JavaScript running in your browser. Our servers are not involved at any point.

Ideal weight for height calculator

Enter your height to see your ideal weight range from three established formulas: Hamwi, Devine, and the BMI healthy range (18.5–24.9). The BMI range gives the broadest and most evidence-based estimate of a healthy weight for your height.

Sex

Height units

Height (cm)

How it works

Three formulas are calculated and shown simultaneously. Hamwi (1964): men 48 + 2.7 per inch over 5 ft; women 45.5 + 2.2 per inch over 5 ft. Devine (1974): men 50 + 2.3 per inch over 5 ft; women 45.5 + 2.3 per inch over 5 ft. WHO BMI range applies BMI 18.5–24.9 to height (m²) to give a weight range. Imperial inputs are converted to metric (1 ft = 30.48 cm, 1 in = 2.54 cm) before calculation. All arithmetic runs locally in your browser.

Processing runs in your browser

All calculations happen locally in your browser tab. Our servers are not involved at any point.

Technical specification

The Hamwi formula was published by G.J. Hamwi in Therapy: Changing Dietary Concepts (1964) and is widely used in clinical pharmacy. The Devine formula was published by B.J. Devine in Anaesthesia (1974) and is standard in drug dosing for renally cleared medications. The WHO BMI range (18.5–24.9) is derived from the WHO Technical Report Series 894 (2000) and is considered the most broadly evidence-based reference.

Hamwi formula: Hamwi, 1964, clinical rule of thumb
Devine formula: Devine, Anaesthesia, 1974
WHO BMI range: BMI 18.5–24.9 (WHO TRS 894, 2000)
Browser API: Pure JavaScript arithmetic. No library

Related operations

For a general weight category from height alone, try the BMI calculator. To measure body composition with circumference inputs, use the body fat calculator. For daily energy targets at a goal weight, see the calorie calculator.

Frequently asked questions

Which ideal weight formula is most accurate?: No single formula is universally accurate. The BMI-range method (18.5–24.9 applied to height) is the most evidence-based and gives a range rather than a single number. Hamwi and Devine are older clinical rules of thumb still used in pharmacy and medicine.
Why do the three formulas give different results?: Hamwi (1964) and Devine (1974) were derived from clinical populations and produce a single point estimate. The BMI-range method is derived from epidemiological data and is broader. Individual factors like muscle mass and frame size mean no formula is perfectly accurate for everyone.
Does ideal weight differ by body frame size?: Some clinicians add ±10% to ideal weight estimates for small or large frames. However, there is no standardised method for measuring frame size, so this adjustment is rarely used in practice.
Is my data sent to a server?: All calculations are pure JavaScript running in your browser. Our servers are not involved at any point.