Ideal Weight Calculator

How to Use the Ideal Weight Calculator

Our free ideal weight calculator estimates your optimal body weight using four of the most widely referenced medical formulas: Devine, Robinson, Miller, and Hamwi. Start by selecting your unit system — metric (centimeters) or imperial (inches). Enter your height, select your gender, and choose your frame size (small, medium, or large). The calculator instantly displays the ideal weight from each formula, their average, a frame-adjusted value, and a recommended weight range. All results update in real time as you change any input.

Knowing your ideal weight range can help you set realistic fitness goals, track progress, and make informed decisions about nutrition and exercise. Unlike BMI, which only tells you whether your weight-to-height ratio falls in a general category, ideal weight formulas give you a specific target number adjusted for your body frame.

Understanding the Four Formulas

The Devine formula (1974) was originally created to calculate drug dosages based on body weight. It estimates ideal weight as 50 kg (males) or 45.5 kg (females) for a height of 5 feet, adding 2.3 kg for each additional inch. The Robinson formula (1983) is a refinement that uses slightly different base weights and increments: 52 kg plus 1.9 kg per inch for males, and 49 kg plus 1.7 kg per inch for females. The Miller formula (1983) starts with higher base weights — 56.2 kg for males and 53.1 kg for females — but uses smaller increments of 1.41 and 1.36 kg per inch respectively. Finally, the Hamwi formula (1964) uses 48 kg plus 2.7 kg per inch for males and 45.5 kg plus 2.2 kg per inch for females.

Frame Size and Its Impact

Your body frame — determined by bone structure and skeletal width — significantly impacts your natural weight. People with larger frames have heavier bones and can carry more lean mass at the same height. The calculator adjusts the average ideal weight by minus 10% for a small frame and plus 10% for a large frame. To estimate your frame size at home, wrap your thumb and index finger around your wrist: if they overlap, you likely have a small frame; if they just touch, a medium frame; and if they do not meet, a large frame.

Using Ideal Weight as a Guide

Ideal weight formulas provide useful benchmarks, but they are not definitive health indicators. They do not account for muscle mass, body fat distribution, age, or ethnic differences. Athletes and highly active individuals may naturally weigh more than their calculated ideal weight due to greater muscle mass. For a comprehensive assessment, consider using ideal weight alongside BMI, body fat percentage, and waist circumference measurements, and always consult a healthcare professional for personalized guidance.

Frequently Asked Questions

How is ideal body weight calculated?

Ideal body weight is estimated using medical formulas based on your height and gender. The most commonly used formulas are Devine (1974), Robinson (1983), Miller (1983), and Hamwi (1964). Each formula uses a base weight for a height of 5 feet and adds a set amount per inch above that. The results vary slightly between formulas, so averaging them provides a more reliable estimate.

What is the Devine formula for ideal weight?

The Devine formula (1974) calculates ideal body weight as follows: for males, 50 kg + 2.3 kg for each inch over 5 feet; for females, 45.5 kg + 2.3 kg for each inch over 5 feet. It was originally developed for drug dosage calculations and has become one of the most widely referenced ideal weight formulas.

Does frame size affect ideal weight?

Yes, frame size (small, medium, or large) significantly affects ideal weight. People with larger bone structures naturally weigh more at the same height. A common adjustment is minus 10% for a small frame and plus 10% for a large frame relative to the medium frame baseline. You can estimate your frame size by measuring your wrist circumference.

Is ideal body weight the same as a healthy weight?

Ideal body weight formulas provide a general target, but a healthy weight range is broader. BMI between 18.5 and 24.9 is considered healthy for most adults. Ideal weight formulas do not account for muscle mass, body composition, or individual health factors. Use them as a general guide rather than an absolute target.

Why do different ideal weight formulas give different results?

Each formula was developed using different study populations, time periods, and methodologies. Devine's formula was created for pharmaceutical dosing, while others were derived from actuarial or clinical data. The differences are usually small — typically within 5-10 pounds of each other. Averaging multiple formulas gives a more balanced estimate.