# Ideal Body Weight Calculator | Forge > **Quick Answer:** The Forge Ideal Body Weight Calculator runs the Devine, Robinson, Miller, and Hamwi formulas side by side and headlines their average, with a frame-size range of plus or minus 10 percent. Free and ungated. Example: a 6'0" man averages about 169 lb across the four formulas. These formulas describe an average untrained adult, so anyone who lifts should treat the answer with suspicion and track body composition instead. **dateModified:** 2026-08-09 --- ## Key Facts - **Four formulas:** Devine (1974), Robinson (1983), Miller (1983), Hamwi (1964), computed exactly as published - **Headline:** The arithmetic mean of the four, which usually land within a few pounds of each other - **Frame range:** The classic convention adjusts the estimate by about 10 percent up for a large frame and 10 percent down for a small one - **Inputs:** Sex and height. Heights under 5 feet extrapolate below the original data. - **Units:** Imperial and metric (formulas return kilograms, pounds convert at 1 kg = 2.20462 lb) - **Context:** The formulas see height and sex. Muscle never enters the math, so lifters often sit above every estimate while being lean. - **Cost:** Free. No sign-up. --- ## How to Use It 1. Pick your sex. 2. Enter your height. 3. Read the headline average and the four individual formula results. 4. Check the frame range under the headline if your wrists and ankles run notably wide or narrow. 5. If you lift, take the number as trivia and head to the body fat or lean body mass calculators for something that responds to training. --- ## How the Math Works Devine, Robinson, Miller, and Hamwi, each computed exactly as published. Your height converts to inches over 5 feet, the formulas return kilograms, and pounds convert at 1 kg = 2.20462 lb. The headline is the arithmetic mean of the four. The frame range applies the classic 10 percent adjustment up or down. The four formulas were published between 1964 and 1983, each fitting a simple line to a reference population. They answer one narrow question: what does an average, mostly untrained adult of your height tend to weigh. Devine became the most cited because hospitals adopted it for medication dosing, which says more about convenience than accuracy. A lifter carrying 15 to 20 lb more muscle than the reference population sits above every formula while being leaner than the estimate assumes. Heights under 5 feet extrapolate below the original data, so treat that output as a rough sketch. --- ## Frequently Asked Questions ### What is ideal body weight? Ideal body weight is a statistical estimate of a typical weight for your height and sex. The four formulas here were published between 1964 and 1983, each fitting a simple line to a reference population. They answer one narrow question: what does an average, mostly untrained adult of your height tend to weigh. ### Which formula should I trust? None of them alone. Devine became the most cited because hospitals adopted it for medication dosing, which says more about convenience than accuracy. The four formulas usually land within a few pounds of each other, so their average is the most useful single number on this page. ### I lift. Why does my number look so low? Muscle is the reason. A lifter carrying 15 to 20 lb more muscle than the reference population will sit above every formula while being leaner and healthier than the estimate assumes. These formulas see your height and sex. Your body composition never enters the math. ### What should I use instead? Body composition. Our body fat calculator estimates your fat percentage from tape measurements, and the lean body mass calculator turns that into the weight of your muscle, bone, and water. Those numbers respond to training. A height-based formula stays frozen while you change. ### Do the formulas work if I am under 5 feet tall? They still compute, since each formula subtracts its per-inch amount below the 5-foot base. The error grows quickly down there because the original data barely covered those heights, so treat the output as a rough sketch. ### What about frame size? Frame size is real. Wider wrists and ankles usually come with more bone and muscle at the same height. The classic convention adjusts the estimate by about 10 percent up for a large frame and 10 percent down for a small one, which is the range shown under the headline. --- ## Forge Tracks What Changes With Training Forge is an AI personal trainer for iOS and Android. It builds an adaptive plan around your goals, schedule, and equipment, logs every workout, and adjusts as you progress. You get 4 trainer personalities and a 24/7 trainer chat. Pricing: $19.99/month, $59.99/year, or $6.99/week. All plans include a 7-day free trial. - **App Store:** https://apps.apple.com/us/app/forge-ai-personal-trainer/id6758403402 - **Google Play:** https://play.google.com/store/apps/details?id=com.tendylabs.forge - **Website:** https://forgetrainer.ai --- *https://forgetrainer.ai/tools/ideal-body-weight-calculator*