Ideal Weight Calculator — 4 Clinical Formulas
Last reviewed: April 2026
The ideal weight calculator compares four widely-cited clinical formulas — Hamwi (1964), Devine (1974), Robinson (1983), and Miller (1983) — to give you a range of "ideal body weight" estimates for your height and sex. These formulas were originally developed in clinical and pharmaceutical settings to approximate lean body mass for medication dosing and were later adopted as general reference points. Because each formula was derived from different population samples and assumptions, they can differ by 5–15 lbs for the same person. No single number represents everyone's ideal weight — healthy weight is best understood as a range that also accounts for frame size, muscle mass, age, and individual health status. This tool displays all four estimates side by side, along with a healthy weight range based on a BMI of 18.5–24.9 for your height.
Calculate Your Ideal Weight Range
Ideal Weight by Formula
Healthy Weight Range (BMI 18.5 – 24.9)
| Formula | Year | Ideal Weight | ±10% Frame Range | Original Purpose |
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Why do the formulas differ? Each was developed from a different population sample with different goals. The Hamwi formula was created for clinical use at Metropolitan Life Insurance. Devine was designed for drug dosing in pharmacy — not intended as a fitness target. Robinson and Miller were later modifications of Devine derived from different reference populations. None were derived from comprehensive health outcome data.
What about frame size? Body frame (wrist circumference relative to height) can shift your ideal range by roughly ±10%. A person with a larger skeletal frame naturally carries more bone and connective tissue and may weigh more while still being at a healthy composition. Wrist circumference is a common proxy: for women, wrist < 5.5 in = small frame; 5.5–5.75 in = medium; >5.75 in = large. For men: < 6.5 in = small; 6.5–7.5 in = medium; > 7.5 in = large.
The bottom line: "Ideal weight" is a range, not a single number. Your best target weight depends on your body composition, health history, and personal goals. A registered dietitian or physician can help you set a personalized, realistic weight goal.
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Why Ideal Weight Is a Range, Not a Single Number
Every formula on this page outputs a single number, but your healthiest weight is actually a range. Two people with identical height and sex can look and feel completely different at the same body weight depending on muscle mass, bone density, body frame, and fat distribution. The BMI-based healthy weight range shown in the results — using the WHO standard of 18.5–24.9 — is generally a more defensible reference than any single formula, because it explicitly acknowledges the window of healthy weights rather than implying a precise target.
Body frame size alone can account for a 10–15 lb difference in appropriate weight at the same height. A large-framed person carries more skeletal mass and may weigh more while having lower body fat than a smaller-framed person at the formula's "ideal." Muscle mass adds further variation: a strength-trained person with excellent cardiovascular health may weigh 15–25 lbs above what Devine or Hamwi suggests, yet have a far better metabolic profile than someone at the formula target through inactivity.
"Ideal weight" is most useful as a directional benchmark — a rough starting point for goal-setting, not a verdict on your current health. For a personalized target, a physician or registered dietitian can account for your actual body composition, health history, and goals.
Frequently Asked Questions
Which ideal weight formula is most accurate?
None of the four formulas — Hamwi, Devine, Robinson, or Miller — was designed to predict health outcomes in the general population. All were created for narrow clinical purposes (drug dosing, hospitalized patient care) using limited historical datasets. For a general reference, the BMI-based healthy range (18.5–24.9 applied to your height) is the most widely supported benchmark, as it reflects the WHO classification used in population health research. Even so, no formula replaces a clinical assessment that accounts for body composition, health history, and personal goals.
Can you be healthy outside the ideal weight range?
Yes — many people are in excellent health at weights above or below what these formulas predict. A muscular athlete may weigh significantly above the formula range while having low body fat and outstanding cardiovascular fitness. Conversely, some people within the range have poor metabolic health markers. Weight is one data point among many. Blood pressure, blood glucose, cholesterol, aerobic capacity, and muscle strength are all meaningful health indicators that a scale cannot capture on its own.
Does ideal weight change as you age?
The four clinical formulas use only height and sex — they do not adjust for age. However, body composition shifts naturally over time: adults typically lose muscle and gain fat mass from their 30s onward, even when the scale stays the same. Some research suggests slightly higher BMI ranges (up to 27) may be associated with better outcomes in adults over 65, partly because modest fat reserves provide energy during illness. A physician can help you set an age-appropriate weight target that accounts for your current health status and body composition.
Is ideal weight different for muscular or athletic people?
Yes, significantly. Muscle tissue is denser than fat tissue, so a strength-trained person can weigh substantially more than formula-based ideal weights while being leaner and healthier than someone who hits the number through inactivity. If you train regularly, your practical ideal weight may be 10–20% above what these formulas suggest. Body fat percentage — measured via DEXA scan, hydrostatic weighing, or the Navy circumference method — is a more meaningful indicator of body composition than weight alone. See our Navy Body Fat Calculator for a body composition estimate.
Related Calculators
Sources & Methodology
Formulas used: Hamwi (1964) · Devine (1974) · Robinson (1983) · Miller (1983). Each formula starts from a base weight at 5 ft and adds a per-inch increment for heights above that, adjusted for sex. BMI-based range uses the WHO healthy BMI range (18.5–24.9) applied to height.
Sources: Hamwi GJ (1964) Therapy: changing dietary concepts. Diabetes; Devine BJ (1974) Gentamicin therapy. Drug Intell Clin Pharm; Robinson JD et al. (1983); Miller DR et al. (1983). These formulas are population-level estimates — they do not account for body composition, muscle mass, or individual health factors.
Last reviewed: April 2026