Ideal Weight Calculator
Compare your ideal body weight across four established formulas, plus your healthy BMI weight range
What Is Ideal Body Weight?
Ideal body weight (IBW) is an estimated weight considered generally healthy for a given height and gender. Rather than relying on a single formula, this calculator compares four well-established methods — Hamwi, Devine, Robinson, and Miller — alongside the healthy BMI weight range, so you get several reference points instead of one rigid number.
Formulas Used
Hamwi (1964) — Male: 48.0 kg + 2.7 kg per inch over 5 ft
Hamwi (1964) — Female: 45.5 kg + 2.3 kg per inch over 5 ft
Devine (1974) — Male: 50.0 kg + 2.3 kg per inch over 5 ft
Devine (1974) — Female: 45.5 kg + 2.3 kg per inch over 5 ft
Robinson (1983) — Male: 52.0 kg + 1.9 kg per inch over 5 ft
Robinson (1983) — Female: 49.0 kg + 1.9 kg per inch over 5 ft
Miller (1983) — Male: 56.2 kg + 1.41 kg per inch over 5 ft
Miller (1983) — Female: 53.1 kg + 1.36 kg per inch over 5 ft
The primary "Ideal Weight" figure shown in your results is the Hamwi formula adjusted for frame size (±10% for small/large frames), since frame size most directly affects this particular formula in common clinical use.
Explanation of Every Input
Gender
Each formula uses different base weights and per-inch increments for men and women, reflecting average differences in frame and composition.
Height
All formulas calculate a base weight for 5 feet (152.4 cm) and add a fixed amount per inch of height beyond that.
Frame Size
Frame size adjusts the primary Hamwi-based estimate by roughly ±10% to account for skeletal structure — see the FAQ below for how to estimate your own frame size from wrist circumference.
Current Weight (Optional)
If entered, the calculator shows how far your current weight is from each formula's estimate and from the healthy BMI weight range.
Healthy BMI Weight Range
In addition to the four formulas, this calculator shows the weight range corresponding to a BMI between 18.5 and 24.9 at your height — a widely used general reference range associated with lower health risk in population studies.
Ideal Weight by Frame Size
Small Frame
Narrower wrists and shoulders. The Hamwi-based estimate is adjusted about 10% lower.
Medium Frame
Average build. The Hamwi-based estimate is used without adjustment.
Large Frame
Broader wrists and shoulders. The Hamwi-based estimate is adjusted about 10% higher.
Advantages of Using This Calculator
- Compares four established formulas instead of relying on just one.
- Shows the healthy BMI weight range as an additional reference point.
- Optionally compares your current weight against every estimate.
- Works in metric or imperial units.
Limitations
- None of these formulas account for muscle mass or body composition.
- Not designed for children, adolescents, or pregnant women.
- Frame size is self-assessed and inherently approximate.
Common Mistakes to Avoid
- Treating a single formula's result as an exact medical target.
- Ignoring muscle mass when comparing results, especially for athletes.
- Assuming Medium Frame without checking wrist circumference guidance.
Worked Examples
Medium-Frame Woman
Profile: Female, 165 cm, Medium Frame
Hamwi: 58.5 kg Devine: 58.5 kg
Robinson: 58.9 kg Miller: 56.3 kg
Healthy BMI Range: 50.4 - 67.8 kg
At this height, all four formulas cluster within about 2.6 kg of each other, giving a confident estimate.
Large-Frame Man
Profile: Male, 183 cm, Large Frame
Hamwi: 82.1 kg Devine: 82.5 kg
Robinson: 79.6 kg Miller: 75.6 kg
Healthy BMI Range: 62.2 - 83.7 kg
The Large Frame adjustment raises the Hamwi estimate above the other unadjusted formulas, reflecting a bigger skeletal structure.
Small-Frame Woman
Profile: Female, 158 cm, Small Frame
Hamwi: 46.3 kg Devine: 51.5 kg
Robinson: 54.3 kg Miller: 51.6 kg
Healthy BMI Range: 46.2 - 62.1 kg
The Small Frame adjustment pulls the Hamwi-based estimate toward the lower end of the healthy BMI range.
Tall Medium-Frame Man
Profile: Male, 190 cm, Medium Frame
Hamwi: 87.5 kg Devine: 85.8 kg
Robinson: 81.9 kg Miller: 77.9 kg
Healthy BMI Range: 66.8 - 89.9 kg
For taller heights, the formulas spread out more — Hamwi and Devine trend higher than Robinson and Miller.
Frequently Asked Questions
How accurate is this ideal weight calculator?
This calculator uses four well-established formulas (Hamwi, Devine, Robinson, and Miller) alongside the healthy BMI weight range, so you can compare several estimates rather than relying on a single number. Individual factors like muscle mass, bone density, and body composition still mean the real healthy weight for any person can fall outside these estimates.
Why do the different formulas give different results?
Each formula was developed at a different time using different reference populations and study goals — Devine (1974) was created for medical drug-dosing calculations, while Hamwi (1964) was designed for quick clinical estimates. The formulas agree closely for many heights but can diverge somewhat, especially for people who are notably tall or short.
What is frame size and why does it matter?
Frame size refers to the size of your skeletal structure — small, medium, or large — based on wrist and elbow measurements relative to height. A larger frame supports more lean mass and bone at a healthy weight, so this calculator adjusts the Hamwi-based estimate by roughly ±10% depending on frame size.
How do I know my frame size?
A common method is to measure your wrist circumference: for women, under 14 cm is typically small frame, 14-14.6 cm medium, and over 14.6 cm large; for men the thresholds are slightly higher. If you are unsure, Medium Frame is a reasonable default.
What is the healthy BMI weight range?
The healthy BMI weight range is the span of body weights that correspond to a Body Mass Index between 18.5 and 24.9 at your height — the range generally associated with lower health risk in population studies. It is shown alongside the formula-based estimates as an additional reference point.
Should athletes use this calculator?
Athletes and people with significant muscle mass often weigh more than these formulas suggest while still being lean and healthy, since none of these formulas account for body composition. Body fat percentage is typically a more meaningful measure of health for very muscular individuals.
Which formula should I trust most?
No single formula is definitively "best" — Devine is the most widely used in clinical settings (including medication dosing), while the average of all four formulas shown here gives a reasonable, well-rounded estimate for general reference.
What if my current weight is far from my ideal weight range?
These estimates are general reference points, not medical targets — a large gap does not necessarily mean anything is wrong. If you are concerned about your weight, consult a healthcare professional who can consider your full health picture, not just height and gender.
Do these formulas work for children?
No — all of the formulas used here (Hamwi, Devine, Robinson, Miller) were developed for adults and are not appropriate for estimating a healthy weight for children or adolescents, who should be assessed using pediatric growth charts instead.
Can I use pounds and inches instead of kilograms and centimeters?
Yes — Advanced Options lets you switch height to inches and any current weight you enter to pounds, and the calculator converts everything internally so results stay accurate regardless of units.
Conclusion
No single formula perfectly captures what "ideal weight" means for every individual, which is why comparing several established methods alongside the healthy BMI range gives a more balanced picture. Use these estimates as general reference points, not strict targets, and consult a healthcare professional for personalized guidance.