Ideal Weight Calculator

“Ideal weight” formulas have an interesting and often overlooked history: several of the most widely cited ones weren’t originally developed as a public wellness target at all — they were built for calculating medication dosages. This calculator shows four of these classic formulas side by side, along with the modern BMI-based healthy range for comparison.

How the Ideal Weight Calculator Works

Enter your sex and height, and the calculator applies four established formulas — Robinson (1983), Miller (1983), Devine (1974), and Hamwi (1964) — each producing a specific reference weight, alongside the standard healthy BMI range (18.5 to 25) converted into actual weight boundaries for the same height.

The Devine Formula: Born From a Practical Clinical Need, Not a Wellness Goal

The Devine formula, published in 1974, is perhaps the most consequential of the four historically, because it was developed specifically to help calculate drug dosages — many medications need to be dosed based on an estimate of “ideal” body weight rather than actual weight, particularly for patients who are significantly overweight or underweight, since actual weight in those cases can lead to inaccurate dosing if used directly. Devine’s formula was a practical clinical tool for that specific purpose, not a public-facing wellness benchmark — its widespread adoption as a general “ideal weight” reference happened later, extending it well beyond its original, narrower clinical dosing context.

The Hamwi Formula: The Oldest of the Four, From a Different Clinical Tradition

Predating Devine by a decade, the Hamwi formula (1964) emerged from a similar clinical nutrition and dosing tradition, developed as a quick, easy-to-calculate reference for clinicians working without more sophisticated body composition tools available at the time. Like Devine’s, it uses a base weight adjusted by a fixed amount per inch of height over a reference point — a simple, linear calculation that was practical to compute by hand in a clinical setting decades before body composition analysis tools became widely available.

Robinson and Miller: Later Refinements to the Same Basic Approach

The Robinson (1983) and Miller (1983) formulas, both published the same year, refined the same basic height-based linear approach as Devine and Hamwi before them, adjusting the specific coefficients based on additional research data available by the early 1980s. Despite being developed independently and refining the same underlying concept, all four formulas share the same fundamental structure: a base weight for a reference height, adjusted by a fixed amount for each inch above that reference — which is exactly why they tend to track reasonably close to each other, even though their specific numerical outputs differ.

Why These Four Formulas Disagree — Sometimes by 10 Pounds or More

Because each formula was calibrated using different research data at different points across two decades, they can produce noticeably different specific weight figures for the identical height — a gap of 10 pounds or more between the highest and lowest of the four isn’t unusual. This spread itself is informative: it demonstrates that even among established clinical reference formulas developed by different researchers, there’s no single universally agreed “ideal” weight number for a given height, which is exactly why this calculator shows all four together rather than presenting one as definitively correct.

Why the BMI Range Is Generally More Relevant Today

Given that three of these four formulas originated specifically for clinical dosing purposes rather than general wellness guidance, the standard BMI-based healthy weight range — developed and validated specifically for general population health screening — is generally considered the more directly relevant reference for everyday health purposes. This calculator includes that BMI-based range specifically for that reason: while the four historical formulas offer interesting reference points and remain in occasional clinical use for their original dosing purpose, the BMI range is the more appropriate general-purpose comparison for most people checking this calculator out of general health interest rather than a specific clinical dosing need.

What None of These Formulas Can See: Individual Body Composition

All four historical formulas, along with the BMI range itself, are calculated from height alone (or height and weight, for BMI) — none can account for individual differences in muscle mass, bone density, or frame size, all of which genuinely affect what a healthy weight looks like for a specific person. An athletic, muscular individual can reasonably and healthily exceed every one of these reference figures without carrying excess body fat at all, which is exactly why these numbers should be treated as general population reference points rather than individually tailored targets.

BMI Calculation Directly

The healthy range this calculator includes is derived from the standard BMI formula. The BMI Calculator performs that calculation in the more commonly needed direction — computing your actual current BMI from your height and weight, along with additional detail like BMI Prime and category classification.

Lean Body Mass: A Different Way to Think About Ideal Weight

Rather than a single ideal weight figure, some people find lean body mass — the weight of everything in the body that isn’t fat — a more useful reference point, since it accounts for the distinction between muscle and fat that these height-based formulas can’t capture. The Lean Body Mass Calculator estimates that figure using three different established formulas.

Body Fat Percentage for a More Individualized Assessment

For an estimate that incorporates actual body measurements rather than height and weight alone, the Body Fat Calculator uses circumference measurements to estimate body fat percentage directly, offering more individualized input than any of these height-based ideal weight formulas.

Frequently Asked Questions

Were these ideal weight formulas originally designed for general wellness use?

Not entirely — several, including Devine’s, were originally developed specifically to help calculate medication dosages for patients whose actual weight might lead to inaccurate dosing. Their adoption as general “ideal weight” wellness references came later, extending them beyond their original clinical purpose.

Why do the four formulas give such different results for the same height?

Because each was calibrated using different research data at different points across roughly two decades (1964 to 1987), producing results that can differ by 10 pounds or more for the identical height. This reflects genuine disagreement even among established clinical formulas about a single ideal figure.

Which formula should I actually trust?

None is universally considered more accurate than the others, which is exactly why this calculator shows all four together. For general health reference purposes, the standard BMI-based healthy range is generally considered more directly relevant than any single one of these historical dosing-derived formulas.

Are these formulas still used clinically today?

Some, particularly Devine’s, remain in occasional clinical use for their original purpose — estimating ideal body weight for certain medication dosing calculations — even though they’re now more commonly encountered by the general public as informal wellness reference points.

Can a muscular person healthily exceed all four formulas’ results?

Yes — none of these formulas account for muscle mass, bone density, or body frame, so an athletic, muscular individual can reasonably and healthily weigh more than any of these figures suggest without that additional weight representing excess body fat.