Ideal Weight Calculator

About this tool

The Ideal Weight Calculator computes suggested ideal body weight with four widely cited medical formulas: Hamwi (1964), Devine (1974), Robinson (1983) and Miller (1983). Choose male or female, pick cm/kg or in/lbs, and enter your height; the results update as you type. Alongside the four formula results the tool shows their average and the weight range that corresponds to a BMI of 18.5-24.9 at your height. Each formula was developed for a different clinical context — Devine is widely used in pharmacology for drug dosing, Hamwi in nutritional assessments — so showing them together makes clear there is no single 'ideal' weight. The formulas are defined from 5 ft (60 in / 152 cm) upward; for shorter heights the tool shows a note instead of results.

Why use it

• Shows results from the four classic ideal weight formulas side by side.

• Demonstrates the range of targets rather than a single misleading number.

• Adds the average of the four formulas and the BMI 18.5-24.9 weight range for comparison.

• Supports metric (cm/kg) and imperial (in/lbs) units.

• Educational tool that demystifies the wide range across published 'ideal weight' formulas — there is no single correct answer.

• Privacy-first: height and sex inputs stay in your browser and are never logged or transmitted.

How to use

1. Select Male or Female (each formula uses different constants by sex).
2. Choose cm / kg or in / lbs to set the height input and result units.
3. Enter your height — in centimetres, or in total inches (for example 70 for 5'10").
4. Read the four formula results, which update as you type.
5. Check the average of the four formulas and the healthy BMI weight range shown below them.
6. Treat the spread between the lowest and highest formula result as a target band rather than chasing one number.

When it helps

• Setting a personal goal weight range for a fitness or health program.
• Clinical reference for medication dosing calculations based on ideal body weight.
• Educational comparison of different medical weight estimation formulas.
• Getting a realistic healthy weight range beyond a single-point target.
• Curious about how different historical formulas would categorize your weight at your height.
• Discussing body composition goals with a coach or trainer who needs a starting target band.

Examples

Tips

• Compare all four formula results and aim for a healthy weight within the band rather than chasing a single specific number.
• Use the BMI-based range (BMI 18.5-24.9) as the most modern and inclusive target — older formulas like Hamwi were calibrated to mid-20th-century averages.
• Adjust the target upward by 5-10% if you have visibly higher-than-average muscle mass — these formulas underestimate ideal weight for athletes.
• Skip these formulas entirely for clinical applications like medication dosing — let your physician calculate from validated pharmacy references.
• Weigh yourself separately and compare against the band weekly; if you stay 5%+ above the upper limit for 6+ weeks, consider a structured fat-loss approach.
• Remember that ideal weight tells you nothing about body composition — two people at the same 'ideal' weight can have wildly different fat-to-muscle ratios.

Frequently Asked Questions

Glossary

Hamwi formula (1964)

Men: 48 kg + 2.7 kg per inch above 5 ft. Women: 45.4 kg + 2.2 kg per inch above 5 ft in this tool (often published as 45.5 kg). Created by G.J. Hamwi for diabetes management.

Devine formula (1974)

Men: 50 kg + 2.3 kg per inch above 5 ft. Women: 45.5 kg + 2.3 kg per inch above 5 ft. The pharmacology standard for IBW dosing.

Robinson formula (1983)

Men: 52 kg + 1.9 kg per inch above 5 ft. Women: 49 kg + 1.7 kg per inch above 5 ft. A modernized refinement of Devine.

Miller formula (1983)

Men: 56.2 kg + 1.41 kg per inch above 5 ft. Women: 53.1 kg + 1.36 kg per inch above 5 ft. Slightly higher target than other formulas.

BMI (Body Mass Index)

Weight (kg) / height² (m²). Normal range 18.5-24.9. The BMI-based ideal weight is the weight range corresponding to BMI 18.5-24.9 at your height.

Ideal Body Weight (IBW)

A reference weight historically used in clinical pharmacology to standardize medication dosing for tall, short, or obese patients.

Adjusted Body Weight (ABW)

IBW + 0.4 × (actual weight − IBW); used in dosing calculations for obese patients to avoid under- or overdosing.