Ideal Weight Calculator

Why Four Different Formulas?

This calculator uses four established scientific formulas — Devine, Robinson, Miller, and Hamwi — and displays the range across all four. Each was developed independently by different researchers using different population datasets, which is why they produce slightly different results.

• Devine Formula (1974): The most widely cited formula, originally developed by Dr. B.J. Devine for calculating medication dosages. It remains commonly used in clinical settings. For men: 50 kg + 2.3 kg per inch over 5 feet. For women: 45.5 kg + 2.3 kg per inch over 5 feet.
• Robinson Formula (1983): Developed by J.D. Robinson as a refinement of Devine's work. Produces slightly lower estimates than Devine for most heights.
• Miller Formula (1983): Developed by D.R. Miller, also as a modification of the Devine formula. Tends to produce the highest estimates of the four.
• Hamwi Formula (1964): One of the oldest formulas, originally published by G.J. Hamwi. Uses a slightly different base weight and increment per inch.

No single formula is universally superior. Showing the range across all four gives you a more realistic picture of where a healthy weight for your height might fall, rather than a false sense of precision from a single number.

Ideal Weight vs Healthy Weight: What's the Difference?

These terms are related but not identical. Ideal weight formulas produce a single target number (or a narrow range) based purely on height and sex. Healthy weight, as defined by the World Health Organization, is a broader range determined by BMI — specifically, the weight that gives a BMI between 18.5 and 24.9.

For most people, their ideal weight from these formulas falls within their healthy BMI range — but not always. If your calculated ideal weight sits outside your healthy BMI range, the BMI range is generally considered the more clinically meaningful guide. You can check your current BMI using our BMI Calculator.

Limitations of Ideal Weight Formulas

These formulas were developed primarily from studies of hospitalised or military populations and may not represent the general public accurately. Key limitations include:

• They do not account for body composition. A highly muscular person may significantly exceed the ideal weight estimate while having excellent health. An older adult who has lost muscle may fall within range while having a high body fat percentage.
• They do not account for ethnicity. Research suggests that people of Asian descent may have higher health risks at lower body weights, while some other groups may have different healthy weight ranges from what these formulas suggest.
• They treat all heights the same. The linear inch-based increments in these formulas may overestimate ideal weight for very tall individuals and underestimate it for shorter individuals.
• They were designed for adults. These formulas should not be applied to children, teenagers, or pregnant women.

What to Do With Your Result

Your ideal weight range is a useful reference, not a strict prescription. Here are practical next steps depending on where you currently stand:

• Use the BMI Calculator to see your current weight category and healthy weight range for your height.
• Use the Calorie Calculator to find your daily energy needs — this is the most actionable number for managing weight.
• Use the Body Fat Calculator if you want to understand your body composition beyond just weight.
• Read our guide on how to lower your BMI if you are above your healthy range, or consult a healthcare professional for personalised guidance.