Calculate your ideal body weight using four proven medical formulas — Hamwi, Devine, Robinson, and Miller. Compare results and find your healthy weight range.
By Formula:
These are statistical estimates, not personal health targets. Consult a healthcare professional for personalized advice.
Enter your height and gender to calculate ideal weight
This ideal weight calculator — usable as a straightforward perfect weight calculator, too — estimates a healthy weight for your height using four established clinical formulas: Hamwi, Devine, Robinson, and Miller. Rather than relying on a single number, it shows all four results side by side plus their average, so you can see the natural spread between formulas built for different purposes. Free to use in both metric (cm/kg) and imperial (ft/lbs) units, it also adjusts for body frame size and includes an age-aware informational note, making it more personalized than a plain height-weight chart.
This calculator doesn't measure anything about your actual body composition — it calculates a statistical reference weight from your height, gender, and frame size, using formulas built from historical clinical and actuarial datasets. Each formula starts from a base weight at exactly 5 feet of height and adds a fixed amount for every inch above that, then the calculator shifts the result up or down by roughly 10% depending on the body frame size you select.
This ideal weight calculator is useful for anyone setting a broad weight goal, clinicians and pharmacists who want a quick reference figure for ideal body weight (the Devine formula in particular is still used in medication dosing), and anyone who wants a sanity check on where their current weight sits relative to long-used medical benchmarks. Results are shown in both ideal weight kg and ideal weight in lbs, so it works equally well as an imperial or metric ideal weight calculator. It's designed for adults; for anyone under 18, a pediatric growth chart is more appropriate.
Ideal weight formulas give doctors and pharmacists a standardized reference point — the Devine formula in particular remains widely used for calculating medication dosages by ideal body weight rather than actual weight, since some drugs need to be dosed relative to lean body mass rather than total mass. For general use, comparing across all four formulas rather than trusting just one gives a more balanced picture, and pairing that with a healthy weight BMI range or a body fat percentage reading gives a fuller sense of where a reasonable target might sit.
Exactly how this ideal weight calculator converts your height into four reference weights
The calculator computes all four adjusted results, averages them for the headline "Average Ideal Weight" figure, and compares your current weight against that average. It also shows a ±10% band around each individual formula's result (displayed as its "range") as a broader visual reference — separate from, and applied on top of, the frame-size adjustment above.
Men: 48 kg + 2.7 kg per inch over 5 ft. Women: 45.5 kg + 2.2 kg per inch over 5 ft. Originally developed as a quick clinical reference for medication dosing calculations.
Men: 50 kg + 2.3 kg per inch over 5 ft. Women: 45.5 kg + 2.3 kg per inch over 5 ft. Popular in pharmacology and critical care medicine for drug dosing by ideal body weight.
Robinson (Men): 52 kg + 1.9 kg per inch over 5 ft. Miller (Men): 56.2 kg + 1.41 kg per inch over 5 ft. Derived from insurance actuarial height-weight data.
From entering your height to comparing four formula results
Gender determines which set of base weights and per-inch multipliers each of the four formulas uses.
Pick Metric (cm/kg) or Imperial (ft/lbs), then enter your height. This is the only measurement all four formulas require.
Type your current body weight so the calculator can show how far it sits above or below the four-formula average.
Age triggers an informational note for under-18 or 65+ users. Frame size shifts every formula's result by roughly 10% up or down.
See all four formula results with their ranges, the overall average, your current weight, the difference from that average, and two comparison charts.
Using the calculator's own default scenario — a man, 170 cm tall, 75 kg, medium frame
A man is 170 cm tall, weighs 75 kg, and has a medium body frame (no frame adjustment applied).
Explanation: All four formulas land within about 1.5 kg of each other (65.2 to 66.7 kg) for this height, which shows the kind of natural agreement you can expect between formulas built on different historical data. Because no age was entered in this example, no age-related informational note is shown. A 13.7% difference from the average falls in the "moderately above average" interpretation band described below — not extreme, but a reasonable prompt to look at body composition alongside the number.
How to read the "Difference from Ideal" figure against the four-formula average
| Difference from Average Ideal Weight | Interpretation | General Consideration |
|---|---|---|
| Within ±5% | Very close to average | Your current weight closely matches the four-formula average for your height and frame |
| 5–10% above or below | Within typical range | Still within the ±10% band these formulas treat as broadly expected |
| 10–20% above average | Moderately above average | Worth considering alongside body composition and other health markers, not weight alone |
| 10–20% below average | Moderately below average | Worth considering alongside body composition and other health markers, not weight alone |
| More than 20% above or below | Notably outside typical range | A conversation with a healthcare professional is a reasonable next step |
If your result falls within ±10% of average: this generally aligns with the range these formulas treat as typical for your height and frame — no specific action is implied by the number alone.
If your result falls more than 10% above or below average: the individual formula results and their ranges give you more context than the single average figure. Body composition, muscle mass, and overall health markers matter more than closing the gap to a formula's output.
This result is for informational purposes only and is not a medical diagnosis. These four formulas are statistical estimates from historical population data, not an individual diagnostic measure — they do not know your muscle mass, body fat percentage, or medical history.
This calculator provides educational estimates only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Results may vary depending on individual health conditions. Always consult a qualified healthcare professional regarding medical concerns.
Where a four-formula reference weight is genuinely useful
Use the four-formula average as an evidence-informed starting point instead of an arbitrary target number.
See how Hamwi, Devine, Robinson, and Miller compare for your exact height instead of trusting just one number.
Understand how the Devine formula is used as an ideal-body-weight reference point in medication dosing contexts (informational only).
Compare your current weight to a statistical benchmark and see the percentage difference from average.
Coaches can use the average and range as one data point among several when discussing goals with clients.
Adjust a reference weight for small, medium, or large body frame instead of using a flat height-weight chart.
Switch freely between metric and imperial units — useful for international travelers, expats, or bilingual households.
Bring an objective reference figure into a conversation with a dietitian alongside other body composition data.
Get a periodic sanity check on your weight relative to established medical reference formulas.
Students and educators can use the worked formulas to illustrate how ideal body weight has historically been estimated.
Establish a reference figure before starting a weight-management plan, to revisit later alongside progress data.
See side-by-side how four historically significant formulas diverge for the same height and gender.
Check a weight goal given by another source (app, chart, or provider) against four independent formulas.
What this ideal weight calculator does well, and where it can't replace professional advice
Base weight at 5 feet and the per-inch multiplier each formula adds above that
| Formula (Year) | Men — Base / Per Inch | Women — Base / Per Inch |
|---|---|---|
| Hamwi (1964) | 48 kg + 2.7 kg/in | 45.5 kg + 2.2 kg/in |
| Devine (1974) | 50 kg + 2.3 kg/in | 45.5 kg + 2.3 kg/in |
| Robinson (1983) | 52 kg + 1.9 kg/in | 49 kg + 1.7 kg/in |
| Miller (1983) | 56.2 kg + 1.41 kg/in | 53.1 kg + 1.36 kg/in |
Summary: This free ideal weight calculator gives you an instant reference weight from four established medical formulas — Hamwi, Devine, Robinson, and Miller — in metric or imperial units, adjusted for body frame size, with an age-aware note. It's a useful sanity-check tool, not a medical diagnosis. Pair it with related tools like the BMI Calculator and Body Fat Calculator for a fuller picture of your healthy weight range and body composition.
Common questions about ideal weight and the formulas used
Men: 48kg + 2.7kg per inch over 5ft. Women: 45.5kg + 2.2kg per inch over 5ft. Originally developed for medication dosing calculations in clinical settings.
Men: 50kg + 2.3kg per inch over 5ft. Women: 45.5kg + 2.3kg per inch over 5ft. Popular in pharmacology and critical care medicine for drug dosing by ideal body weight.
Robinson (Men): 52kg + 1.9kg per inch over 5ft. Miller (Men): 56.2kg + 1.41kg per inch over 5ft. These formulas use slightly different multipliers derived from insurance actuarial data.
Population note: All four formulas were developed using primarily Western population data from the 1960s–1980s. For South Asian and East Asian users, results may slightly overestimate ideal weight, as these populations show higher metabolic risk at lower BMI levels. Consider using the BMI-based healthy range (18.5–23 for South/East Asian populations) alongside these estimates.
Official guidance to complement this calculator — not a substitute for licensed medical advice
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