Six science-backed formulas in one place — Robinson, Miller, Devine, Hamwi, Peterson, and the BMI healthy range. Get your consensus target with frame size adjustment, unit conversion, and a to-goal timeline.
Sex
Height unit
Display unit
Sex
Height unit
Formula
Display unit
How to find your frame size: Wrap your thumb and middle finger around your wrist. Small: fingers overlap. Medium: fingertips just touch. Large: fingers don’t meet. Frame size shifts ideal weight by about ±10%.
Sex
Height unit
Frame size
Display unit
Sex
Unit system
Safe: 0.25–1.0 kg/wk
The Six Ideal Weight Formulas Explained
Ideal body weight (IBW) formulas estimate a target weight based on height and sex. They were developed for specific medical and clinical purposes and remain in use today in pharmacology, nutrition, and fitness. Each formula takes height above 5 feet (60 inches / 152.4 cm) as its primary input and produces a single point estimate — not a range. The BMI-based range (18.5–24.9) is the broadest and most commonly cited healthy weight window.
Formula
Year
Male base (at 5ft)
Female base
Per inch over 5ft
Primary use
Robinson
1983
52 kg
49 kg
+1.9 / +1.7 kg
General medicine; most widely cited
Miller
1983
56.2 kg
53.1 kg
+1.41 / +1.36 kg
Nutritional assessment
Devine
1974
50 kg
45.5 kg
+2.3 / +2.3 kg
Pharmacy drug dosing (most cited in clinical settings)
Hamwi
1964
48 kg
45.4 kg
+2.7 / +2.2 kg
Quick nutritional needs estimation
Peterson
2016
2.2×BMI + 3.5×BMI×(height−1.5m)
BMI 22 target
Most recent; addresses height non-linearity
BMI Range
—
18.5–24.9 × height(m)²
N/A
Broadest healthy weight window
Which Formula Is Most Accurate?
No single formula is universally “best” — they were designed for different purposes and validated on different populations. For general use, Robinson (1983) is the most widely cited in medical literature. Devine (1974) is the standard formula used by pharmacists to calculate drug doses for obese patients. Peterson (2016) is the most recently published and specifically designed to address a mathematical limitation of earlier formulas: the linear-per-inch structure overestimates ideal weight for very tall people and underestimates it for very short people.
The practical difference between formulas is usually small — 3 to 8 kg (7 to 18 lbs) across all five point estimates for a given height. Your true ideal weight almost certainly falls within the range defined by the lowest to highest formula result. The consensus range (average minus 5% to average plus 5%) is more useful than any single formula.
Frame Size and Why It Matters
Frame size refers to skeletal size — the width of your bones. It is most commonly estimated using wrist circumference or elbow breadth. A large-framed person has broader, denser bones that weigh more and naturally support more muscle, making a higher body weight appropriate. A small-framed person has a lighter skeleton and is optimally lean at a lower weight. Most IBW formulas assume a medium frame; adjusting by ±10% for small or large frames provides a more personalized target.
Method
Small Frame
Medium Frame
Large Frame
Wrist wrap test
Thumb & finger overlap
Tips just touch
Gap remains
Male elbow breadth
< 6.4 cm (2.5 in)
6.4–7.3 cm
> 7.3 cm (2.9 in)
Female elbow breadth
< 5.7 cm (2.25 in)
5.7–6.3 cm
> 6.3 cm (2.5 in)
IBW adjustment
−10%
0% (baseline)
+10%
Ideal Weight vs BMI vs Body Fat
These three measures look at body weight from different angles. Ideal body weight formulas give a single-number target based purely on height and sex — fast and simple, but they ignore age, muscle mass, and body composition. BMI tells you where you currently are relative to population norms; a healthy BMI (18.5–24.9) corresponds to the BMI-range formula here. Body fat percentage is the most informative measure: a muscular person may be 20 lbs above their IBW with only 12% body fat and be in excellent health, while someone at their “ideal” weight with 32% body fat faces the same metabolic risks as an obese person.
Use ideal weight formulas as a rough navigational target, not a medical prescription. The formulas are most useful for tracking direction of change over time, setting initial weight-loss goals, and clinical dosing calculations — not for judging whether a specific weight is healthy for a specific individual.
Ideal Weight by Height — Reference Table
The following table shows the Robinson formula result (the most commonly referenced in general medicine) alongside the healthy BMI weight range for common heights.
Height
Robinson IBW (male)
Robinson IBW (female)
Healthy BMI range
5’0” (152 cm)
52.0 kg / 115 lbs
49.0 kg / 108 lbs
43–58 kg / 95–127 lbs
5’4” (163 cm)
59.6 kg / 131 lbs
55.8 kg / 123 lbs
49–66 kg / 108–146 lbs
5’7” (170 cm)
65.3 kg / 144 lbs
60.9 kg / 134 lbs
53–72 kg / 118–158 lbs
5’10” (178 cm)
71.0 kg / 156 lbs
66.1 kg / 146 lbs
58–79 kg / 129–173 lbs
6’0” (183 cm)
74.8 kg / 165 lbs
69.5 kg / 153 lbs
63–84 kg / 138–186 lbs
6’2” (188 cm)
78.6 kg / 173 lbs
72.9 kg / 161 lbs
66–89 kg / 146–196 lbs
Frequently Asked Questions
Why do the five formulas give different results?
Each formula was developed in a different decade (1964–2016), for a different primary purpose, using different population datasets. Devine (1974) was designed for pharmacy and tends to give slightly higher weights for men. Hamwi (1964) uses round numbers for quick clinical estimation. Robinson and Miller (both 1983) are more modern statistical updates. Peterson (2016) specifically addressed the mathematical problem that all earlier formulas assume a strictly linear relationship between height and ideal weight, which over-predicts for very tall people. The typical spread between all five formulas for a given height is 5–10 kg (10–22 lbs).
Do ideal weight formulas work for athletes and muscular people?
No — this is the most important limitation of IBW formulas. Muscle tissue is denser than fat and weighs significantly more per unit of volume. A 5’10” male with 10% body fat and significant muscle mass might weigh 185 lbs while the Robinson formula suggests 156 lbs. That extra 29 lbs is almost entirely lean muscle — healthier, not worse. Athletes and those who lift regularly should use body fat percentage as their primary metric, not ideal weight formulas. The IBW range becomes more reliable as a health signal for sedentary or lightly active individuals.
Should ideal weight be different for older adults?
The traditional IBW formulas do not adjust for age, but research suggests they probably should. Metabolic risk associated with being slightly overweight (BMI 25–27) appears to decrease with age, and some studies find slightly higher BMI is associated with lower mortality in adults over 65 — likely because weight loss in older adults often reflects muscle and bone loss rather than fat loss. A 70-year-old at the same IBW as a 30-year-old may actually have less muscle and more fat at the same scale number. For older adults, maintaining muscle mass through resistance training and adequate protein is more important than hitting a specific weight target.
What is the Peterson formula and why is it different?
Published by Peterson et al. in 2016, this formula uses the equation: IBW = 2.2 × 22 + 3.5 × 22 × (height in meters − 1.5). Unlike earlier formulas that add a fixed amount per inch of height, Peterson’s formula is derived from a BMI of 22 (middle of the healthy range) and maintains that relationship across all heights. This prevents the over-prediction of ideal weight for people above 6 feet and the under-prediction for people below 5 feet that affects the older formulas. It is the most mathematically consistent with healthy BMI targets.
Do these formulas apply to all ethnicities?
The classic IBW formulas were developed primarily on Caucasian populations and have known limitations for other ethnic groups. Research consistently finds that people of Asian descent face metabolic risks (type 2 diabetes, cardiovascular disease) at lower body weights and BMIs than the standard thresholds suggest. The World Health Organization’s Asia-Pacific guidelines suggest lower healthy weight thresholds for East and Southeast Asian populations. Conversely, some studies find that people of African descent have higher average bone density and muscle mass, making a slightly higher weight appropriate at the same height. These are population-level patterns; individual assessment with a healthcare provider is always more accurate.
How is the “consensus range” calculated?
The consensus range in this calculator is the range from the lowest to highest point estimate across all five IBW formulas (Robinson, Miller, Devine, Hamwi, Peterson). It represents the full spread of scientifically published ideal weight targets for your height and sex. The average of all five formulas is used as the central reference point. This range is typically 5–10 kg wide and is more useful as a practical target than any single formula result, since it acknowledges that “ideal weight” is inherently a range, not a precise number.