What Is Ideal Body Weight (IBW)?
Ideal Body Weight (IBW) is a clinically derived target weight for a given height and sex. It was originally developed in the 1960s and 1970s to help medical professionals calculate appropriate drug dosages — particularly for medications where dosing based on actual body weight in obese patients would lead to overdosing. Over time, IBW calculations became broadly used in nutrition, fitness, and health contexts as a reference point for healthy weight goals.
It is important to understand that IBW is not a perfect measure of health. Body composition — the ratio of lean muscle to fat — matters as much as total weight. An athletic person may exceed their IBW while having very low body fat, whereas someone at their IBW might still carry excessive visceral fat. Always use IBW alongside other measures such as BMI, waist circumference, and body fat percentage for a complete health picture.
This ideal weight calculator uses four widely-cited IBW formulas and also shows the healthy BMI-based weight range (BMI 18.5–24.9) for your height, giving you a realistic, evidence-informed healthy weight target.
The 4 IBW Formulas Explained
Four major formulas are used to determine ideal body weight. Each was derived from different population studies and intended for different clinical contexts. All four use height in inches as the primary input and produce results in kilograms.
| Formula | Men (kg) | Women (kg) | Context |
|---|---|---|---|
| Devine (1974) | 50 + 2.3 × (H″ − 60) |
45.5 + 2.3 × (H″ − 60) |
Most widely used; standard for pharmaceutical dosing |
| Hamwi (1964) | 48 + 2.7 × (H″ − 60) |
45.5 + 2.2 × (H″ − 60) |
Oldest formula; common in dietetics practice |
| Robinson (1983) | 52 + 1.9 × (H″ − 60) |
49 + 1.7 × (H″ − 60) |
Refined from Devine; broader population study |
| Miller (1983) | 56.2 + 1.41 × (H″ − 60) |
53.1 + 1.36 × (H″ − 60) |
Typically higher estimate; useful for muscular frames |
Where H″ = height in total inches. For heights under 5 feet (60 inches), the formulas use proportional adjustments. Note that IBW formulas do not account for body frame size, age, or muscle mass — they are estimates, not prescriptions.
How to Use This Ideal Weight Calculator
Choose Your Unit System
Select Metric (centimetres) or Imperial (feet and inches). The calculator converts automatically — results are shown in both kg and lbs regardless of which unit you use for input.
Select Your Gender
Biological sex affects IBW calculations because men and women have different muscle mass distributions and bone density. All four formulas use different base constants for men and women. Select accordingly for an accurate result.
Enter Your Height
In metric mode, enter your height in centimetres (e.g. 175). In imperial mode, enter feet and inches separately. Height is the only required input — the calculator derives all four IBW values instantly from this single measurement.
Add Your Current Weight (Optional)
Entering your current weight is optional. If provided, the calculator shows a weight gap analysis — exactly how far above or below your ideal weight you currently are — and displays a visual progress bar showing your position within the healthy BMI range.
Review Your Results
The results show your Devine IBW as the primary reference, all four formula values for comparison, the BMI-based healthy weight range, and — if you entered your current weight — a personalised gap analysis with actionable context.
Ideal Weight for Men vs Women
All four IBW formulas use different base values for men and women. Generally, the male IBW is 4–7 kg higher than the female IBW at the same height. This reflects average differences in lean muscle mass and skeletal density between biological sexes.
For example, at 175 cm (5'9"):
— Male IBW (Devine): ~71.7 kg — Female IBW (Devine): ~67.1 kg
The Hamwi formula produces slightly higher values for men relative to women than Devine does, while Robinson and Miller produce a closer spread. None of the formulas account for hormonal status, menopause, pregnancy, or athletic conditioning — consult a registered dietitian for personalised targets if these factors apply.
Ideal Weight vs. BMI: Key Differences
The BMI calculator tells you where your current weight falls — underweight, normal, overweight, or obese — relative to a population-based scale. The ideal weight calculator tells you what a target weight would be based on clinical formulas and your height.
The BMI healthy range (18.5–24.9) typically translates to a weight range of roughly 8–12 kg for most adults at a given height. The four IBW formulas tend to cluster within the lower half of this BMI-healthy range. If your IBW result seems low, cross-referencing it with the BMI healthy range can help you set a more realistic and personalised target weight.
To understand your full calorie and nutritional picture alongside your ideal weight, you may also find the BMR calculator and calorie calculator helpful — together they form the foundation of evidence-based weight management.
Staying Hydrated on Your Weight Journey
Hydration plays a meaningful role in body weight management. Many people confuse mild dehydration with hunger, leading to excess calorie intake. Drinking adequate water before meals has been shown in multiple studies to reduce calorie consumption. To find out exactly how much water your body needs daily based on your weight, activity, and climate, use the daily water intake calculator.