Calculators
Ideal Weight Calculator
Compare historical height-based formulas and an adult BMI reference. None of these numbers defines your ideal weight or a personal health goal.
Historical formula comparisons and an adult BMI reference for ages 20+. These values do not set your ideal weight, diagnose health or determine medication doses. Not intended for children, teens or pregnancy.
Enter a height between 122 cm (4 ft) and 244 cm (8 ft) to compare ideal weight estimates.
Formula coefficients and sources
Let x be height in inches minus 60. Male/female weights in kg: Robinson 51.65 + 1.85x / 48.67 + 1.65x; Miller 56.2 + 1.41x / 53.1 + 1.36x; Devine 50 + 2.3x / 45.5 + 2.3x; Hamwi 48 + 2.7x / 45.5 + 2.2x. Hamwi is a rounded metric version. No frame-size adjustment is applied.
Primary research: Robinson et al., 1983. BMI reference: CDC adult categories and screening limitations.
Your inputs are calculated in your browser and are not uploaded by this tool.
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Frequently asked questions
What does ideal weight mean here?
It is the historical name of these formulas, not a claim that there is one correct weight for you. They use height and male/female coefficients without assessing your body composition, medical history or circumstances. The results are presented for comparison and explanation.
How do the named formulas work?
Each starts with a weight assigned at 5 feet and adds a fixed number of kilograms per additional inch. The complete coefficients appear beside the calculator. Robinson uses the coefficients in the linked original paper; the Hamwi version uses rounded metric coefficients. No frame-size adjustments are applied.
What happens below 5 feet?
The named formula comparison is hidden below its 5-foot base instead of pretending that every shorter person has the same calculated weight. The adult BMI reference can still be displayed within the tool’s accepted height range of 4–8 feet. The page does not extrapolate a shorter-height version of the four formulas.
What does the BMI interval show?
It solves weight = BMI × height in metres squared at BMI 18.5 and 25, with the upper endpoint excluded. These are the CDC adult reference boundaries for ages 20 and older. Displayed weights are rounded to one decimal; this interval is a screening reference, not proof of health or an instruction to gain or lose weight.
Can this be used for children, pregnancy or medication dosing?
No. This page is intended only as an adult comparison and has no adjustment for growth, pregnancy, clinical conditions or drug-specific dosing requirements. A label that appears in a medical calculation does not make this general-purpose tool suitable for that decision.
Why are two people of the same height given the same result?
Because age, muscle mass, body shape, medical history and other individual factors are not inputs to these height-based formulas. That is a limitation of the model. The calculator cannot determine which result, if any, is appropriate for either person.
About this tool
This page puts several commonly named historical calculations side by side so their differences are visible. It does not average them into a new target or rank one as the correct personal answer. The formula details and source links let you see what is actually being calculated.
Height is converted to inches for the named formulas. For example, 5 feet 9 inches is nine inches above the base. Using the male coefficients from the original Robinson paper gives 51.65 + 1.85 × 9 = 68.30 kg. Other listed formulas give different results because their coefficients differ, not because the tool has collected more information about the person.
The BMI panel uses a separate calculation in metres and shows the interval from 18.5 up to, but not including, 25. The CDC source linked beside it explains why BMI is a screening measure to consider with other factors. This tool does not infer an individual’s health from being inside or outside that interval.
When checking the arithmetic, keep the inputs and units visible. Imperial height uses whole feet and additional inches below 12; displayed outputs use kilograms or pounds according to your unit choice. Calculations run in the browser, and this tool does not upload or save the measurements.