Ideal Body Weight & Body Fat Calculator Online Free
Enter height and sex to compare four classic clinical ideal-body-weight formulas side by side: Robinson, Miller, Devine and Hamwi. Switch metric or imperial units, pick any formula row to treat as your selected target, and see BMI plus weight delta against your current weight. Useful for medication dosing discussions, nutrition worksheets and classroom demos of how different equations diverge — all calculated offline in your browser.
Ideal Body Weight & Body Fat Calculator In-Browser Workspace
Input data or select files to begin. 100% private, client-side execution with zero server transmission.
How to Use Ideal Body Weight & Body Fat Calculator
- Step 1: Choose biological sex (formula constants differ) and metric or imperial units.
- Step 2: Enter height in cm, or feet plus extra inches for imperial.
- Step 3: Enter current weight in kg or lb for BMI and delta comparison.
- Step 4: Click Calculate Ideal Weight to run Robinson, Miller, Devine and Hamwi.
- Step 5: Click a result row to select that formula; review BMI and Δ vs current weight.
About Ideal Body Weight & Body Fat Calculator
Ideal body weight (IBW) equations predict a “desirable” weight from height (and sometimes sex) without measuring body composition. Devine (1974) uses 50 + 2.3 inches over 60 for men and 45.5 + 2.3 × inches over 60 for women; Hamwi (1964) uses 48 + 2.7 and 45.5 + 2.2 per inch over 60. Robinson (1983) softens the slope (52 + 1.9 for men, 49 + 1.7 for women) and Miller (1984) sits between Hamwi and Devine for many heights. All four were built around 5 ft–6 ft adult cohorts, so values far below 60 in or above ~78 in are extrapolations — the tool warns when you leave the validated band. IBW ignores frame size, muscle mass, age and ethnicity; BMI = weight(kg) / height(m)² is shown only as a screening context (WHO bands: underweight <18.5, normal 18.5–24.9, overweight 25–29.9, obese ≥30). Δ vs current weight is simply current_kg − selected_target_kg. For modern body-composition goals, waist circumference and DEXA-style methods outperform any single height-only formula. This tool is for education and clinical-reference arithmetic — not a diet plan.
Frequently Asked Questions
Which formula is most accurate?
None is a gold standard for body composition. Devine and Hamwi are common in dosing; Robinson/Miller are alternatives — treat results as a range.
Why do the four answers differ?
Each study used different cohorts and intercepts/slopes per inch over 5 ft, so targets diverge more at taller heights.
Do these formulas work for children or pregnancy?
No — they were derived for adults. Use age/sex-specific pediatric or obstetric tools instead.
Is BMI included?
Yes, as context only. BMI does not distinguish fat from muscle and can misclassify athletes.
Is this medical advice?
No. Discuss weight goals and dosing with a qualified healthcare professional.