Ideal Weight Calculator

Calculate your ideal body weight using multiple medical formulas and compare healthy weight ranges.

Ideal Weight Calculator

Estimate a reference body weight for your height and sex using several published medical formulas. These formulas were originally developed for tasks such as drug dosing, and today they serve as rough benchmarks rather than personal targets.

The formulas

The most widely cited ideal body weight formulas all start from a base weight at 5 feet (152.4 cm) and add a fixed amount per inch (2.54 cm) of height above that:

  • Devine (1974), men: IBW = 50 kg + 2.3 kg per inch over 5 ft
  • Devine (1974), women: IBW = 45.5 kg + 2.3 kg per inch over 5 ft
  • Robinson (1983), men: IBW = 52 kg + 1.9 kg per inch over 5 ft
  • Robinson (1983), women: IBW = 49 kg + 1.7 kg per inch over 5 ft
  • Hamwi (1964), men: IBW = 48 kg + 2.7 kg per inch over 5 ft
  • Hamwi (1964), women: IBW = 45.5 kg + 2.2 kg per inch over 5 ft

The Devine formula remains the standard in clinical pharmacology. Because each author derived their formula differently, the results form a range rather than a single answer, and many clinicians also compare them against the healthy BMI range of 18.5 to 24.9 for the same height.

Worked example

A man who is 5 feet 10 inches tall (about 178 cm) is 10 inches over 5 feet:

  • Devine: 50 + 2.3 x 10 = 73 kg;
  • Robinson: 52 + 1.9 x 10 = 71 kg; and
  • Hamwi: 48 + 2.7 x 10 = 75 kg.

The three formulas place his reference weight between roughly 71 and 75 kg. For comparison, the healthy BMI range at 178 cm spans about 59 to 79 kg, which is considerably wider.

How to interpret your result

Ideal weight formulas are screening references, not prescriptions. They consider only height and sex, ignoring frame size, muscle mass, age, ethnicity, and body composition, so a muscular or athletic person can be perfectly healthy well above every formula's output. The spread between formulas for the same person shows how approximate they are. A weight that supports your health, activity, and lab results matters more than matching any single equation.

Practical tips

  • Treat the range across formulas, not one number, as the meaningful output.
  • Compare the result with the healthy BMI band for your height for extra context.
  • Consider body composition; two people at the same weight can look and perform very differently.
  • Avoid setting an aggressive goal weight from a formula alone, especially if it implies rapid loss.
  • Recheck expectations with a professional if the suggested range feels far from your history.

Related calculators

The BMI calculator screens your current weight against your height, and the lean body mass calculator estimates how much of your weight is fat-free tissue. The BMR calculator estimates resting calorie needs, while the calories burned calculator and pace calculator support activity planning.

This calculator does not replace assessment or advice from a qualified healthcare or nutrition professional.

Frequently asked questions

Which formulas does the ideal weight calculator use?
It uses the published Devine (1974), Robinson (1983), and Hamwi (1964) formulas. Each starts from a base weight at 5 feet of height and adds a fixed number of kilograms per inch above that, with separate coefficients for men and women.
Why do the formulas give different answers?
Each author derived their formula from different data and assumptions, so results for the same height typically spread across a few kilograms. That spread is a feature, not an error: it shows these are rough reference points, and the range is more meaningful than any single value.
Is ideal body weight a target I should aim for?
Not by itself. The formulas consider only height and sex, ignoring frame size, muscle mass, age, and body composition, so a muscular person can be healthy well above every formula's output. They were originally created for purposes such as drug dosing rather than goal setting.
How does ideal weight relate to BMI?
The healthy adult BMI range of 18.5 to 24.9 defines a weight band for each height, and it is usually much wider than the spread of ideal-weight formulas. For a 178 cm man, the formulas cluster around 71 to 75 kg, while the healthy BMI band spans roughly 59 to 79 kg.
Do these formulas work for children or very short adults?
No. The formulas were derived for adults and behave poorly below 5 feet (152 cm), where the per-inch adjustment no longer applies cleanly. Children and teenagers should be assessed with age- and sex-specific growth references instead.
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