Ideal Weight Calculator - Free Online Tool

Calculate your ideal body weight using six scientifically validated formulas

Welcome to our free Ideal Weight Calculator, a comprehensive tool that estimates your ideal body weight using six scientifically recognized formulas: Devine, Robinson, Miller, Hamwi, Peterson, and Lorentz. Rather than relying on a single formula, our calculator compares results across all six methods and provides a healthy BMI-based weight range for a complete picture. Ideal body weight (IBW) formulas were originally developed for medical purposes, particularly for calculating drug dosages and setting clinical benchmarks. Over time, these formulas became widely used for general health assessments. Each formula uses your height and gender to estimate a target weight, with slight variations in their calculations reflecting different research approaches and populations. The Devine formula (1974) is the most commonly used in clinical settings and is the basis for many BMI charts. The Robinson formula (1983) and Miller formula (1983) offer alternative calculations that some researchers consider more accurate for certain populations. The Hamwi formula (1964) is one of the earliest ideal weight equations and remains popular among dietitians. The Peterson formula (2016) is a modern BMI-based approach that calculates ideal weight using a target BMI of 22, making it height-proportional and independent of gender. The Lorentz formula is a widely used European method that provides gender-specific estimates based on height in centimeters. Our calculator also factors in body frame size (small, medium, or large), which significantly affects what weight is healthy for your build. A person with a larger frame naturally carries more bone and muscle mass, so their ideal weight will be higher than someone of the same height with a smaller frame. In addition to the six formula results, we provide a healthy BMI weight range (18.5-24.9) calculated from your height. This gives you a medically recognized range to compare against the formula estimates. All calculations run instantly in your browser with complete privacy. Remember that ideal weight calculators provide estimates based on height and gender. They do not account for muscle mass, body composition, age, or ethnic background. Athletes and muscular individuals may weigh more than their calculated ideal weight while being perfectly healthy. Use these results as general guidelines and consult a healthcare professional for personalized advice.

Understanding Ideal Weight Formulas

Ideal weight formulas estimate a healthy target weight based on height and gender. Each formula was developed by different researchers using different population data, which is why results vary slightly.

The Six Major Formulas

Devine (1974): Men = 50 + 2.3 kg per inch over 5 ft; Women = 45.5 + 2.3 kg. Robinson (1983): Men = 52 + 1.9 kg; Women = 49 + 1.7 kg. Miller (1983): Men = 56.2 + 1.41 kg; Women = 53.1 + 1.36 kg. Hamwi (1964): Men = 48 + 2.7 kg; Women = 45.5 + 2.2 kg per inch over 5 feet. Peterson (2016): IBW = 2.2 x BMI + 3.5 x BMI x (height_m - 1.5) where BMI target = 22, a modern gender-neutral formula. Lorentz: Men = (height_cm - 100) - (height_cm - 150)/4; Women = (height_cm - 100) - (height_cm - 150)/2.5, a popular European formula.

Body Frame Size

Frame size affects ideal weight by 5-10%. To estimate your frame size, wrap your thumb and middle finger around your wrist. If they overlap, you have a small frame. If they just touch, medium. If they don't touch, you have a large frame. Frame adjustments help personalize the formula results.

Formulas

Devine Formula (1974)

Men: IBW = 50 + 2.3 × (height_in − 60) kg | Women: IBW = 45.5 + 2.3 × (height_in − 60) kg

The most widely used formula in clinical medicine and pharmaceutical dosing. Baseline is for 5 feet (60 inches), adding 2.3 kg per additional inch.

Robinson Formula (1983)

Men: IBW = 52 + 1.9 × (height_in − 60) kg | Women: IBW = 49 + 1.7 × (height_in − 60) kg

A refined formula that produces slightly different results, often considered more accurate for the general population than Devine.

Miller Formula (1983)

Men: IBW = 56.2 + 1.41 × (height_in − 60) kg | Women: IBW = 53.1 + 1.36 × (height_in − 60) kg

Tends to give slightly higher ideal weights, which some researchers consider more realistic for modern populations.

Hamwi Formula (1964)

Men: IBW = 48 + 2.7 × (height_in − 60) kg | Women: IBW = 45.5 + 2.2 × (height_in − 60) kg

One of the earliest ideal weight formulas, widely used by dietitians. Uses higher per-inch coefficients than most other formulas.

Reference Tables

Ideal Weight by Height (All Formulas, Medium Frame)

Comparison of ideal body weight in pounds across four major formulas for men and women at common heights

Height	Devine (M/F)	Robinson (M/F)	Miller (M/F)	Hamwi (M/F)
5'0" (152 cm)	110 / 100	115 / 108	124 / 117	106 / 100
5'4" (163 cm)	130 / 120	131 / 123	137 / 129	130 / 120
5'8" (173 cm)	150 / 140	148 / 138	149 / 141	154 / 139
5'10" (178 cm)	161 / 150	156 / 145	155 / 147	166 / 149
6'0" (183 cm)	171 / 161	165 / 152	162 / 153	178 / 158
6'4" (193 cm)	191 / 181	181 / 167	174 / 165	202 / 178

Worked Examples

Example 1: Ideal Weight for a 5'10" Male (Multiple Formulas)

A male with a height of 5'10" (70 inches, 178 cm), medium frame.

Inches over 5 feet = 70 − 60 = 10 inches

Devine: IBW = 50 + 2.3 × 10 = 73.0 kg (161 lbs)

Robinson: IBW = 52 + 1.9 × 10 = 71.0 kg (156 lbs)

Miller: IBW = 56.2 + 1.41 × 10 = 70.3 kg (155 lbs)

Hamwi: IBW = 48 + 2.7 × 10 = 75.0 kg (165 lbs)

Average of four formulas = (73.0 + 71.0 + 70.3 + 75.0) ÷ 4 = 72.3 kg (159 lbs)

The average ideal weight across all four formulas is approximately 72.3 kg (159 lbs). The healthy BMI range for this height is 131–174 lbs.

Example 2: Ideal Weight for a 5'5" Female with Large Frame

A female with a height of 5'5" (65 inches, 165 cm), large body frame.

Inches over 5 feet = 65 − 60 = 5 inches

Devine: IBW = 45.5 + 2.3 × 5 = 57.0 kg (126 lbs)

Robinson: IBW = 49 + 1.7 × 5 = 57.5 kg (127 lbs)

Miller: IBW = 53.1 + 1.36 × 5 = 59.9 kg (132 lbs)

Hamwi: IBW = 45.5 + 2.2 × 5 = 56.5 kg (125 lbs)

Average = (57.0 + 57.5 + 59.9 + 56.5) ÷ 4 = 57.7 kg (127 lbs)

Large frame adjustment (+10%): 57.7 × 1.10 = 63.5 kg (140 lbs)

Frame-adjusted ideal weight is approximately 63.5 kg (140 lbs) for a large-framed 5'5" female.

How to Use the Ideal Weight Calculator

Select Your Gender

Choose male or female. Gender significantly affects ideal weight calculations because men and women have different body compositions, bone density, and muscle mass distributions.

Enter Your Height

Switch between imperial (feet and inches) or metric (centimeters) units, then enter your height. All six formulas use height as the primary variable for calculating ideal weight.

Choose Your Frame Size

Select small, medium, or large body frame. To determine your frame size, wrap your thumb and middle finger around your wrist: overlapping fingers mean small frame, touching means medium, and a gap means large frame.

Review Your Results

Compare ideal weight estimates from the Devine, Robinson, Miller, Hamwi, Peterson, and Lorentz formulas. Check the average ideal weight, healthy BMI range, and frame-adjusted range to get a complete picture of your target weight.

Frequently Asked Questions

What is the most accurate ideal weight formula?

No single formula is universally the most accurate because each was developed using different population samples and methodologies. The Devine formula (1974) is the most widely used in clinical practice and pharmaceutical dosing. The Robinson formula (1983) is often considered more accurate for the general population. The Miller formula (1983) tends to give slightly higher ideal weights, which some researchers believe is more realistic for modern populations. The Hamwi formula (1964) is the oldest and simplest. The Peterson formula (2016) is a modern BMI-based approach that uses a target BMI of 22 and is gender-neutral. The Lorentz formula is a popular European method with gender-specific calculations. Our calculator shows all six so you can see the range. The average of all six formulas typically provides the most balanced estimate for most people.

Why do the different formulas give different results?

Each formula was developed by different researchers using different study populations, time periods, and methodologies. The Devine formula was originally created for calculating medication dosages, not for general health guidance. Robinson and Miller refined the approach using larger datasets in 1983. Hamwi's formula from 1964 uses different coefficients based on earlier population data. The Peterson formula (2016) takes a fundamentally different approach by using a target BMI of 22, making it gender-neutral. The Lorentz formula, widely used in Europe, applies height-based subtractions with gender-specific divisors. These variations in research approach and reference populations explain why results differ by several pounds. The differences are typically small (5-15 pounds) and all results generally fall within the healthy BMI range. Using the average of all six provides a reasonable middle ground.

How does body frame size affect ideal weight?

Body frame size reflects your bone structure and skeletal width, which directly impacts how much you should weigh. People with larger frames have wider bones, broader shoulders, and larger joints, so they naturally carry more weight even at the same height as someone with a smaller frame. Generally, small-framed individuals should target the lower end of the ideal weight range (about 10% below average), while large-framed individuals should target the higher end (about 10% above average). You can estimate your frame size by wrapping your thumb and middle finger around your wrist. This simple test gives a reasonable approximation of your skeletal build.

Are ideal weight formulas accurate for athletes and muscular people?

Ideal weight formulas have significant limitations for athletes and muscular individuals. These formulas only use height and gender as inputs, so they cannot account for muscle mass, which weighs more than fat. A muscular person at 5'10" might weigh 200 pounds with low body fat and excellent health, but the formulas would suggest they are overweight. Similarly, the formulas do not account for age, ethnicity, or body composition. For athletes and active individuals, body fat percentage and waist-to-hip ratio are more useful metrics than ideal weight formulas. Consider using our BMI calculator alongside this tool for additional context.

What is a healthy BMI range and how does it relate to ideal weight?

A healthy BMI (Body Mass Index) falls between 18.5 and 24.9. BMI is calculated by dividing your weight in kilograms by your height in meters squared. Our calculator converts this into a weight range for your specific height, showing you the minimum and maximum weight that would give you a healthy BMI. This BMI-based range is typically wider than the individual formula results and is recognized by the World Health Organization as a standard health metric. Most ideal weight formula results fall within the healthy BMI range. If a formula result falls outside this range, the BMI range may provide a more medically relevant target to aim for.