Devine formula
Male: 50 + 2.3 × inches over 5 ftFemale: 45.5 + 2.3 × inches over 5 ftPublished in a report on gentamicin therapy and later reused as a clinical reference-weight method. It was not designed as a personalized wellness target.
Free adult ideal body weight calculator
Ideal Body Weight (IBW) Calculator
Estimate ideal body weight by height with four common equations: Devine, Robinson, Miller, or Hamwi. Choose the formula you need, then compare all four adult reference estimates in kilograms and pounds.
4 named formulas
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Instant kg & lb results
Free IBW calculator
Calculate adult ideal body weight by height
Select a formula, the sex-specific equation, and your adult height in centimetres or feet and inches. The calculator shows your selected estimate alongside the other three formulas for context.
Formula comparison
How the four ideal body weight formulas work
Each equation starts with a base weight at 5 ft (60 in), then adds its sex-specific amount for every inch above 5 ft. Different coefficients can produce different estimates at the same height.
Robinson formula
Male: 51.65 + 1.85 × inches over 5 ftFemale: 48.67 + 1.65 × inches over 5 ftDerived from height-weight tables for drug-dosage calculations. These are the original reported all-frame coefficients; the paper also describes frame-specific estimates.
Miller formula
Male: 56.2 + 1.41 × inches over 5 ftFemale: 53.1 + 1.36 × inches over 5 ftMiller's 1983 equation uses a higher 5-ft base and a smaller increase per added inch than Devine, so the comparison changes with height.
Hamwi formula
Male: 48 + 2.7 × inches over 5 ftFemale: 45.5 + 2.2 × inches over 5 ftHamwi's original rule is usually reproduced in pounds. This calculator uses one commonly reproduced metric version; conversion and rounding conventions can differ slightly.
Do not average formulas for clinical dosing unless a protocol explicitly tells you to. If a medicine, hospital policy, or professional guideline names Devine, Robinson, Miller, or another method, use that named method rather than substituting a different one.
Interpretation
IBW is a reference weight—not your personal “perfect” weight
Classic IBW equations use only height and a sex-specific coefficient. They do not know your muscle mass, body-fat percentage, bone structure, training status, medical history, or performance goals.
Strength athletes
More lean mass can make a healthy, well-trained athlete weigh more than a height-only IBW estimate. Pair IBW with body composition and performance data.
General fitness
Treat the number as context, not a required target. Trends in waist size, fitness, energy, nutrition, and recovery can be more actionable.
Clinical use
Some dosing or nutrition protocols use a specific reference-weight method. Follow the exact method named by the relevant clinician or protocol.
Practical use
How to put an IBW estimate in context
For most fitness goals, one height-derived number is only one piece of the picture.
Compare, don't chase
Look at how the four formulas cluster rather than treating a single kilogram value as a mandatory goal weight.
Add body composition
If physique change is the goal, body-fat percentage, waist-to-height ratio, and lean-mass trends can provide more specific context.
Match the metric to the goal
Strength, endurance, nutrition, and health goals may need different measurements. Use TDEE, protein, 1RM, or heart-rate tools when those metrics are more relevant.
Use clinical formulas as specified
For medication dosing or medical nutrition decisions, do not substitute a general web calculator for a protocol or clinician-directed calculation.
Common questions
Ideal body weight calculator FAQs
Get quick answers about the formulas, height inputs, and appropriate use of an ideal body weight estimate.
How do I calculate ideal body weight from height?
Each formula starts with a base weight at 5 ft (60 in), then adds a formula-specific amount for every inch above 5 ft. This calculator converts adult height for the selected equation and compares Devine, Robinson, Miller and Hamwi estimates in kilograms and pounds.
Which ideal body weight formula should I use?
There is no single equation that fits every person or purpose. If a clinical or medication protocol names a formula, use that exact method. For general information, compare the estimates and treat them as historical height-based references, not personal targets.
Why do the four ideal body weight results differ?
Devine, Robinson, Miller and Hamwi use different starting weights and height increments. Their estimates can therefore spread apart as height changes; a difference between formulas does not show that one is more accurate for an individual.
Is ideal body weight the same as the healthy BMI weight range?
No. Ideal body weight is estimated with a height-based equation and sex-specific coefficient. The BMI range shown here is a separate adult screening reference based on BMI 18.5–24.9. Neither directly measures body composition or personal health.
Can I use this calculator for medication dosing?
Do not use this general calculator to choose a dose. Some medicine protocols specify an ideal or other dosing weight, but the correct equation and instructions depend on the medicine and patient. Follow the exact protocol and advice from a qualified clinician or pharmacist.
Is this ideal body weight calculator for children or pregnancy?
No. This tool is intended for adults within the height range shown in the calculator. These equations may not be appropriate for children or pregnancy; ask a qualified healthcare professional for individualized guidance.
Tool guide
Understand and use the Ideal Body Weight Calculator
Use these tool-specific notes to understand the method, enter better data, interpret the output, and apply the result appropriately.
What IBW Means
IBW equations are historical height-based reference formulas. They are not direct measurements of healthy body composition and should not be treated as a mandatory target weight.
Enter Height
The classic formulas are primarily height driven and use sex-specific constants. Accurate standing height matters because each additional inch above the reference height changes the estimate.
Compare Equations
Devine, Robinson, Miller, and Hamwi use different coefficients, so a spread between estimates is expected. Seeing several formulas helps show the uncertainty of any single IBW number.
Use With Context
Actual healthy weight can vary with frame, muscle mass, age, health status, and goals. Use IBW as historical reference context rather than as a diagnosis or body-composition prescription.
Frequently asked questions
Ideal Body Weight Calculator FAQs
Practical answers about this tool's inputs, method, results, limitations, and common real-world use.
Which ideal body weight formula should I use?
Use the equation required by the context. If a clinical or medication protocol names Devine, Robinson, Miller, or another method, use that named formula. For general curiosity, compare the formulas rather than treating one as universally correct.
Why do the formulas give different results?
They use different base weights at 5 ft and different per-inch increments. Those coefficient differences create a wider spread as height moves away from 5 ft.
Does IBW use my current weight?
No. These classic equations use height and a sex-specific coefficient only. Your actual weight does not change the IBW estimate.
Can I use this calculator if I am under 5 ft tall?
This page does not extrapolate the standard equations below 5 ft (152.4 cm). If a clinical protocol applies to a shorter adult, follow the method specified by that protocol or qualified professional.
Is ideal body weight the same as a healthy weight?
No. IBW is a historical reference-weight concept. A healthy body weight depends on more than height, and adult BMI healthy-weight ranges are broader than a single IBW number.
Is IBW accurate for athletes?
It can be limited for muscular athletes because the formulas do not measure lean mass or body fat. Use body composition, waist measures, and performance context alongside the IBW estimate.
Why do the IBW formulas give different answers?
They were created for different historical purposes and use different base weights and per-inch adjustments. There is no single universally correct IBW equation for every person.
What happens if I am shorter than five feet?
Some classic equations were framed around a five-foot baseline and are less well supported at shorter heights. Treat extrapolated values cautiously rather than assuming the same linear relationship is validated there.
Does body frame size change the calculator result?
The main equations used here do not directly measure frame size. Some older rules proposed frame adjustments, but they are not a substitute for individualized assessment of body composition or health.
Should I diet until I reach my IBW result?
Not automatically. A formula-based reference weight does not account for your full medical, nutritional, or performance context. Use broader health information and professional guidance when setting weight goals.
Method & references
Sources and methodology
The calculator keeps the four equations separate and shows the coefficients used. Robinson's values are the original all-frame coefficients; Hamwi is shown using a commonly reproduced metric approximation.
- Newfoundland & Labrador Health — Devine IBW formula reference
- Pai & Paloucek — Historical background on ideal body weight equations
- Robinson et al. — Original all-frame equations for drug-dosage calculations
- CDC — Adult BMI categories for healthy-weight context
Content reviewed: .
Health and clinical-use disclaimer
This calculator provides educational adult reference-weight estimates. “Ideal body weight” is a historical clinical term, not a diagnosis or a personalized target. It is not intended for children, pregnancy, or unsupervised medication dosing. For clinical decisions, follow the method specified by the relevant medicine reference, healthcare professional, or institutional protocol.