Ideal Weight Calculator

What Is Ideal Body Weight?

Ideal body weight (IBW) is an estimate of a healthy weight for a person based on their height and biological sex. It was originally developed by physicians to help calculate safe drug dosages, where administering medications based on total body weight could lead to under or over-dosing. Today, it is also used as a general health reference to understand what a reasonable weight target looks like for a given height.

It is important to understand that IBW formulas produce estimates, not precise targets. A person's optimal weight depends on factors including muscle mass, bone structure, age, and overall health, none of which these formulas account for.

What This Calculator Does

This calculator computes your ideal body weight using four widely referenced formulas: Devine, Robinson, Miller, and Hamwi. It presents each result side by side along with an average, giving you a useful range rather than a single number.

Inputs Required

• Biological Sex: Male or female (formulas use different base values for each)
• Height: In feet and inches (imperial) or centimeters (metric)

Outputs Provided

• Ideal Weight per Formula: Results from Devine, Robinson, Miller, and Hamwi formulas
• Average Ideal Weight: The average across all four formulas

How the Calculation Works

All four formulas use height above 5 feet as the key variable. Each adds a fixed weight per inch of height above 60 inches, starting from a base weight.

Devine Formula (1974)

Robinson Formula (1983)

Miller Formula (1983)

Hamwi Formula (1964)

How to Use the Calculator

1. Select imperial or metric units
2. Select your biological sex
3. Enter your height using the sliders
4. View your ideal weight from all four formulas and their average

Example Calculation

A male who is 5 feet 10 inches tall is 10 inches over 5 feet:

• Devine: 50 + (2.3 x 10) = 73 kg (161 lbs)
• Robinson: 52 + (1.9 x 10) = 71 kg (157 lbs)
• Miller: 56.2 + (1.41 x 10) = 70.3 kg (155 lbs)
• Hamwi: 106 + (6 x 10) = 166 lbs (75.3 kg)
• Average: approximately 160 lbs (72.5 kg)

Real World Scenarios

Clinical Drug Dosing Reference

A pharmacist calculating the dose of a weight-sensitive medication for an obese patient uses the IBW formula to avoid dosing based on excess adipose tissue. Using total body weight would result in a dangerously high dose for certain drugs.

Setting a Weight Loss Goal

A person who weighs 220 lbs at 5 feet 8 inches uses the ideal weight calculator to understand that a reasonable long-term target is around 155 to 165 lbs, rather than setting an unrealistic goal based on a celebrity or magazine standard.

Fitness Program Assessment

A personal trainer uses ideal weight ranges as a starting point to discuss realistic health goals with a new client. The four-formula comparison helps the trainer frame the target as a range, not a single fixed number.

Why This Calculation Matters

Understanding a realistic weight range for your height helps you set health goals grounded in physiology rather than appearance trends. These formulas also underpin clinical guidelines for ventilator settings, nutritional support, and medication dosing in medical settings, making them the most widely cited reference points in healthcare.

Common Mistakes to Avoid

• Treating one formula as definitive: Each formula was developed for a specific clinical purpose. The average of all four gives a more balanced estimate than any single formula alone
• Ignoring body composition: A heavily muscular person may weigh more than the ideal weight range and still be in excellent health. Ideal weight does not account for muscle mass
• Applying adult formulas to children: These formulas are validated for adults. Different methods apply to pediatric populations
• Using IBW as your only health measure: Pair this with BMI, body fat percentage, and advice from your healthcare provider for a complete picture