What is the Devine formula?

Men: 50 kg + 2.3 kg per inch over 5 ft. Women: 45.5 kg + 2.3 kg per inch over 5 ft. It was published in 1974 for drug dosing.

Why do the formulas give different answers?

They were derived from different data and for different purposes, so their constants differ. That is why we show the range too.

Does ideal weight depend on frame size?

Yes, people with larger frames and more muscle can be healthy at the upper end of the range or above it.

Do the formulas work for short people?

Not well below 5 ft (152 cm), where they under-estimate. Use the BMI range instead.

Is this suitable for children?

No. Use age-specific growth charts and speak to a health professional for children and teenagers.

Health · Free tool

Ideal Weight Calculator

Healthy weight range for your height, plus the Devine, Robinson, Miller and Hamwi formulas.

There is no single perfect weight for a given height. What exists is a healthy range, plus several "ideal body weight" formulas that clinicians use for specific jobs such as drug dosing and setting ventilators. This calculator shows both, so you can see the band you are aiming for and how the classic formulas compare.

The healthy range comes from the adult BMI categories used by the WHO, the NHS and the CDC: a BMI from 18.5 to 24.9. The four formulas — Devine (1974), Robinson (1983), Miller (1983) and Hamwi (1964) — each give a single number from height and sex. A 2000 review of their origins in the Annals of Pharmacotherapy notes they were never designed as health targets for the public, which is why we show them alongside the BMI range rather than instead of it.

All five numbers are reference points. Muscle mass, frame size, age and ethnicity all change what a healthy weight looks like for an individual.

By DailyCalc Editorial Team · Updated 2026-10-03 · 6-min read · 3 sources cited

● Ideal weight calculator

Health →

Ideal body weight formulas

IBW = base + k × (height in inches − 60); healthy range = 18.5 × h² to 24.9 × h² (h in metres)

Each formula starts from a weight at 5 feet (60 inches) and adds a fixed amount per inch above that. Men / women constants in kilograms: Devine 50 / 45.5 + 2.3 per inch; Robinson 52 / 49 + 1.9 / 1.7; Miller 56.2 / 53.1 + 1.41 / 1.36; Hamwi 48 / 45.5 + 2.7 / 2.2. The formulas were built for adults at least 5 ft tall and under-estimate below that height.

height: Height in cm, converted to inches (÷ 2.54) for the formulas.
base: Formula weight at exactly 5 ft, different for men and women.
k: Kilograms added per inch above 5 ft.
h: Height in metres for the BMI-based range.

Worked example: man, 178 cm

Comparing the healthy range with the four formulas:

Height in inches = 178 ÷ 2.54 ≈ 70.08, so 10.08 inches above 5 ft.
Devine = 50 + 2.3 × 10.08 ≈ 73.2 kg; Robinson = 52 + 1.9 × 10.08 ≈ 71.1 kg.
Miller = 56.2 + 1.41 × 10.08 ≈ 70.4 kg; Hamwi = 48 + 2.7 × 10.08 ≈ 75.2 kg.
Healthy BMI range: 18.5 × 1.78² ≈ 58.6 kg to 24.9 × 1.78² ≈ 78.9 kg.
All four formulas fall inside the healthy range, clustering between about 70 and 75 kg.

Result: Healthy range 58.6–78.9 kg; formulas 70.4–75.2 kg for a 178 cm man.

How to use this ideal weight calculator

Two inputs.

Step 1: Choose sex

Each formula has separate constants for men and women.

Step 2: Enter your height in cm

Measure without shoes. 5 ft 10 in ≈ 178 cm.

Step 3: Read the range first

The BMI-based healthy range is the broad target; the formulas show where single-number estimates land.

When it is useful

Ways people use these figures:

Setting a realistic goal

Aim for anywhere in the healthy range rather than a single "ideal" number.

Understanding clinical notes

Hospitals use Devine-based ideal body weight for some drug doses and ventilator settings; this shows where that figure comes from.

Comparing formulas

A 165 cm woman gets 56.4–59.8 kg from the four formulas and 50.4–67.8 kg as the healthy range.

Short stature

Below 5 ft the formulas under-estimate; the calculator flags it so you rely on the BMI range instead.

Pairing with body fat

If you are heavier than the range but lean, check our body fat calculator before deciding you need to lose weight.

Pro tips

Keep the numbers in perspective:

Waist size and body fat say more about health risk than weight alone — use the waist-to-height calculator too.
Some guidance suggests lower BMI cut-offs for people of South Asian, Chinese and Black African or Caribbean family background; ask your clinician.
Slow, sustained change toward the range matters more than reaching a precise number.
Older adults may be healthier slightly above the lower end of the range; discuss targets with a GP.

Common mistakes

How ideal weight numbers get misused:

Treating one formula as the truth

The four formulas differ by several kilograms for the same person. None is a medical target on its own.

Ignoring muscle

Athletes can be well above formula weights while carrying little fat.

Using it under 5 ft

The formulas were derived for taller adults and give values that are too low below 152 cm.

Applying it to children

Children and teens need age- and sex-specific growth charts, not adult formulas.

Sources & references

The formula, thresholds and guidance on this page were checked against these primary sources. Written and reviewed by DailyCalc Editorial Team; last updated 2026-10-03. Spotted an error? Tell us.

Disclaimer: Educational estimate only — not medical advice. A healthy weight depends on many individual factors; speak to a GP or registered dietitian about personal targets.

FAQs