How to Estimate Your Ideal Body Weight
"What should I weigh?" is one of the most-searched health questions online. There is no single correct answer, because ideal weight depends on height, frame size, muscle mass, age, and sex. But there are four established formulas that clinicians and pharmacists use to estimate a reasonable range.
This guide walks through all four formulas, compares their results side by side, and explains why the number on the scale matters less than body composition and overall health markers.
✨Key takeaways
- Four formulas: Devine (1974), Robinson (1983), Miller (1983), Hamwi (1964).
- All are height-based and give slightly different results — the range is your "ballpark."
- These formulas were designed for medication dosing, not aesthetics. Body composition matters more.
- BMI healthy range (18.5–24.9) provides a broader, less formula-specific target.
The four formulas
Devine (most commonly used): Men: 50 + 2.3 × (height in inches − 60) kg. Women: 45.5 + 2.3 × (height in inches − 60) kg.
Robinson: Men: 52 + 1.9 × (height in inches − 60) kg. Women: 49 + 1.7 × (height in inches − 60) kg.
Miller: Men: 56.2 + 1.41 × (height in inches − 60) kg. Women: 53.1 + 1.36 × (height in inches − 60) kg.
Hamwi: Men: 48 + 2.7 × (height in inches − 60) kg. Women: 45.5 + 2.2 × (height in inches − 60) kg.
Worked example: 5'10" male
Height = 70 inches. Deviation from 60 = 10 inches.
Devine: 50 + 2.3 × 10 = 73 kg (161 lb). Robinson: 52 + 1.9 × 10 = 71 kg (157 lb). Miller: 56.2 + 1.41 × 10 = 70.3 kg (155 lb). Hamwi: 48 + 2.7 × 10 = 75 kg (165 lb).
The range is 155–165 lb. That 10-lb spread is normal — these formulas are estimates, not prescriptions.
Limitations of ideal weight formulas
All four were designed for medication dosing (how much drug to give a patient), not for defining a fitness goal. They ignore muscle mass, bone density, body fat distribution, and frame size.
A muscular person at 5'10" could weigh 185 lb and be healthier than someone at 160 lb with low muscle mass. These formulas would flag the first person as "overweight" and approve the second.
Use them as a rough range, not a target. Pair with BMI (via the BMI Calculator), waist circumference, and body fat percentage for a fuller picture.
A healthier way to think about "ideal weight"
Instead of chasing a number, focus on health markers: blood pressure, resting heart rate, blood glucose, cholesterol, energy levels, sleep quality, and physical function.
A weight at which you feel strong, sleep well, move easily, and have healthy labs is your functional ideal weight — regardless of what any formula says.
If you want to set a calorie target based on a weight goal, use the Calorie Calculator to estimate daily needs at your current and target weights.
Try the calculators referenced in this guide
Put the maths into practice — every calculator is free and runs entirely in your browser.
Frequently Asked Questions
Which formula is the most accurate?
None is definitively "most accurate" because they measure different things. Devine is the most widely used in clinical settings. For most people, the average of all four gives the most balanced estimate.
Do these formulas work for children?
No. These formulas are for adults only. Children use age-and-sex-specific growth charts maintained by the CDC or WHO.
My ideal weight seems too low. Is that normal?
These formulas can underestimate for people with large frames or significant muscle mass. If the number feels unrealistically low, focus on the BMI healthy range instead, which provides a wider band.
The Precision Calculator Editorial Team
The editorial team at Get Precision Calculator writes practical, formula-driven guides that explain the maths behind every calculator on this site. All content is reviewed for accuracy before publishing.
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