Ideal Weight Calculator
Find your ideal body weight using multiple scientific formulas
Quick Answer
Your ideal weight depends on height, gender, and frame size. We use 4 proven medical formulas to give you a reliable range.
Ideal Weight Calculator: formula, worked examples and limitations
A complete reference answer — readable without using the calculator.
Definition
Ideal body weight (IBW) formulas were originally developed for medication dosing, not aesthetics. Each formula sets a base weight at 5 ft (152.4 cm) of height and adds a fixed amount per additional inch.
What it measures
They estimate a statistically typical healthy weight for a given height and sex. They do not account for build, muscle mass or body composition.
Formula
- Devine — men: 50 + 2.3 kg per inch over 5 ft; women: 45.5 + 2.3 kg per inch
- Hamwi — men: 48 + 2.7 kg per inch; women: 45.5 + 2.2 kg per inch
- Robinson — men: 52 + 1.9 kg per inch; women: 49 + 1.7 kg per inch
- Miller — men: 56.2 + 1.41 kg per inch; women: 53.1 + 1.36 kg per inch
Worked examples
Computed with the same engine as the calculator above.
Man, 180 cm
Inputs: height = 180 cm = 70.87 in (10.87 in over 5 ft)
Devine: 50 + 2.3 × 10.87
75.0 kg (Devine), range 71.5–77.3 kg across the four formulas
Woman, 165 cm
Inputs: height = 165 cm = 64.96 in (4.96 in over 5 ft)
Devine: 45.5 + 2.3 × 4.96
56.9 kg (Devine), range 56.4–59.8 kg across the four formulas
| Formula | Man, 180 cm | Woman, 165 cm |
|---|---|---|
| Devine (1974) | 75.0 kg | 56.9 kg |
| Hamwi (1964) | 77.3 kg | 56.4 kg |
| Robinson (1983) | 72.6 kg | 57.4 kg |
| Miller (1983) | 71.5 kg | 59.8 kg |
Method
Height is converted to inches, the inches above 5 ft are multiplied by each formula's coefficient, and all four results are shown so the spread is visible as a range.
Limitations
- The formulas use only height and sex — frame size, muscle mass and age are ignored.
- They lose accuracy below about 150 cm and above about 200 cm of height.
- A weight outside the range is not automatically unhealthy; body composition matters more.
Rounding rules
Weights are displayed with one decimal in kilograms.
Evidence level
Published but limited. These equations were created for clinical drug dosing, not as health or aesthetic targets. They ignore body composition, frame size and ethnicity, so treat the output as a reference range rather than a goal weight.
Sources
Method and reference values last reviewed by the SnapBodyCalc editorial team.
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Learn more
Ideal Weight Calculations: Which Formula Should You Use?Different formulas calculate ideal weight in different ways. Understand the science behind each method and learn how to use these calculations in your health journey.
Read articleRelated Calculators
Frequently Asked Questions
Understanding Ideal Body Weight: Formulas, Science, and Practical Use
The concept of "ideal weight" has evolved since the early 20th century. Originally developed by insurance companies to predict mortality risk, ideal weight formulas now serve as reference points for healthcare, drug dosing, fitness planning, and personal goals. Our calculator uses four medical formulas to provide a comprehensive range — not one magic number, but a realistic zone.
The Four Formulas Explained
Devine (1974): Most widely used clinically, originally for drug dosing. Base weight plus increment per inch over 5 feet. Hamwi (1964): Among the earliest, frequently used by dietitians. Robinson (1983): Updated coefficients from Devine. Miller (1983): Slightly higher estimates, potentially more realistic for larger frames. Each was developed from different population data, explaining the variation.
Why Multiple Results Matter
The 3–7 kg variation between formulas represents a healthy weight zone, not uncertainty. No single formula is universally accurate. Showing the range and average gives you a more honest picture than any single estimate could.
Frame Size: The Missing Variable
None of these formulas account for body frame. A large-framed person (wider shoulders, thicker wrists) naturally weighs more at the same height. Test yours: wrap thumb and middle finger around your wrist. Overlap = small frame (subtract 10%), just touching = medium, gap = large frame (add 10%).
Limitations and Special Populations
These formulas don't account for age, muscle mass, or bone density. Athletes may be 5–15 kg above estimates due to muscle. Older adults (65+) may benefit from slightly higher weights — research shows modest "overweight" BMI is associated with lower mortality in elderly populations. Not suitable for children. For more detail, use our BMI Calculator and Body Fat Calculator.
Ideal Weight vs. Healthiest Weight
Your healthiest weight is where you feel energized, sleep well, have good cardiovascular fitness, maintain healthy blood markers, and can sustain your lifestyle without extreme restriction. This may differ from formula estimates. Combine ideal weight with body fat and WHR from our Waist-to-Hip Ratio Calculator for a complete picture.
Setting Realistic Goals
Aim for 0.5–1 kg per week — faster loss often means muscle loss and metabolic adaptation. Our Calorie Calculator provides personalized targets and our Macro Calculator ensures balanced nutrition. Focus on process goals (exercise 4×/week, 5 vegetable servings daily) rather than fixating on a number.
The Psychology of Weight Goals
Research shows behavior-focused goals produce more sustainable results than outcome-focused ones. Weight naturally fluctuates 1–3 kg daily from water, food volume, and hormones. Weigh weekly at most, track the monthly trend, and remember that strength, energy, and how you feel matter more than any formula output.
Your Data Stays Private
SnapBodyCalc performs all calculations locally in your browser. Your height, sex, and results are never transmitted or stored. Your personal health information remains completely private.