What Is Your Ideal Body Weight? Formulas, Ranges & What the Research Says (2026)

Why “Ideal Weight” Is a Range, Not a Number

The concept of a single ideal body weight is largely a myth. No formula can produce a magic number that applies to every person at a given height. Bodies differ in bone density, frame size, muscle mass, and fat distribution — none of which height alone captures.

What the four major formulas do give you is a clinically useful reference point. They were developed primarily to help physicians estimate appropriate medication doses for patients, not to set fitness targets. Understanding this origin explains both their usefulness and their limits.

According to the CDC (2024), the average American man weighs 199.8 lbs (90.6 kg) and the average woman weighs 170.8 lbs (77.5 kg). Both figures fall well above what any of the four formulas predict as “ideal” — a reflection of the fact that about 73.6% of U.S. adults are currently classified as overweight or obese (CDC, 2024 NHANES data).

The Four Main Ideal Weight Formulas

Each formula uses height as its sole input and produces a target weight in either pounds or kilograms. Here’s how each works and where it came from.

1. Hamwi Formula (1964)

The oldest of the four, developed by Dr. G.J. Hamwi and published in a clinical nutrition context. It’s the simplest to calculate by hand.

• Men: 106 lbs for 5 feet + 6 lbs per inch over 5 feet
• Women: 100 lbs for 5 feet + 5 lbs per inch over 5 feet

Example: a 5’10” man = 106 + (10 × 6) = 166 lbs. A 5’5” woman = 100 + (5 × 5) = 125 lbs.

Hamwi also recommended adjusting ±10% for small or large frame sizes, an acknowledgment that height alone is insufficient.

2. Devine Formula (1974)

Developed by Dr. B.J. Devine for estimating drug doses in clinical pharmacology. Despite being designed for pharmacokinetics, it became the most widely used IBW formula in hospitals.

• Men: 50 kg + 2.3 kg per inch over 5 feet
• Women: 45.5 kg + 2.3 kg per inch over 5 feet

Example: a 5’10” man = 50 + (10 × 2.3) = 73 kg (160.9 lbs). A 5’5” woman = 45.5 + (5 × 2.3) = 57 kg (125.7 lbs).

A 2005 analysis in the Journal of Clinical Pharmacologynoted that the Hamwi and Devine formulas were originally developed for drug dosing and were never validated as fitness targets — yet they remain the two most commonly referenced IBW formulas in clinical practice.

3. Robinson Formula (1983)

Developed by J.D. Robinson as a refinement of Devine, using a slightly different slope per inch. It tends to produce lower estimates, especially for men.

• Men: 52 kg + 1.9 kg per inch over 5 feet
• Women: 49 kg + 1.7 kg per inch over 5 feet

Example: a 5’10” man = 52 + (10 × 1.9) = 71 kg (156.5 lbs). A 5’5” woman = 49 + (5 × 1.7) = 57.5 kg (126.8 lbs).

4. Miller Formula (1983)

Also developed in 1983 by D.R. Miller, the Miller formula generally produces the highest estimates of the four, particularly for men.

• Men: 56.2 kg + 1.41 kg per inch over 5 feet
• Women: 53.1 kg + 1.36 kg per inch over 5 feet

Example: a 5’10” man = 56.2 + (10 × 1.41) = 70.3 kg (154.9 lbs). A 5’5” woman = 53.1 + (5 × 1.36) = 59.9 kg (132.1 lbs).

Formula Comparison: 5’10” Male and 5’5” Female

The four formulas can disagree by as much as 10–15 lbs for the same person. Here’s a side-by-side view:

The 11-lb spread for the male example (154.9 to 166 lbs) illustrates why “ideal weight” is a range. No single formula is right — they’re all reasonable estimates built on slightly different assumptions.

BMI vs. Ideal Body Weight: Which Matters More?

BMI and IBW formulas are both height-based shortcuts. Neither is a diagnostic tool. But they’re used differently.

The World Health Organization defines a healthy BMI as 18.5–24.9, but explicitly notes that BMI is a screening tool, not a diagnostic measure. A BMI outside the healthy range prompts further assessment — it doesn’t confirm anything by itself.

IBW formulas, especially Devine, are primarily used in clinical settings for calculating medication doses, ventilator settings, and nutritional requirements. They’re tools for healthcare providers, not personal fitness benchmarks.

For practical purposes: if you want to know where your weight falls relative to general population norms, BMI is the more common reference. If you’re looking for a specific target number to aim for, the IBW formulas give you a reasonable anchor — just understand the anchor was designed for pharmacists, not trainers.

The Problem with Both: Body Composition

A 185-lb man who is 10% body fat is objectively healthier than a 165-lb man who is 28% body fat — yet the second person might score better on every IBW formula and have a “healthier” BMI.

This is the core limitation. Both BMI and IBW formulas measure weight, not health. What actually predicts metabolic health outcomes is body composition: how much of your body weight is fat versus lean mass (muscle, bone, organs, water).

A 2016 study published in the International Journal of Obesity analyzed data from 40,420 adults and found that BMI misclassifies approximately 54 million Americansas metabolically unhealthy when standard cardiometabolic markers (blood pressure, blood glucose, triglycerides, cholesterol) show they are healthy. Conversely, about 30% of people with a “normal” BMI were metabolically unhealthy.

For athletes, the discrepancy is particularly stark. A competitive powerlifter, NFL lineman, or Olympic weightlifter may carry 230–280 lbs of predominantly lean mass — classifying as “obese” by BMI while having exceptional cardiovascular fitness and metabolic health.

Better Metrics Than Weight Alone

• Body fat percentage: Healthy ranges are roughly 6–24% for men and 16–30% for women, depending on age and fitness goals.
• Waist circumference: The CDC considers risk elevated above 40 inches (102 cm) for men and 35 inches (88 cm) for women.
• Waist-to-height ratio: Research suggests keeping your waist circumference under half your height is a strong predictor of metabolic health.
• Blood markers: Fasting glucose, HbA1c, triglycerides, HDL cholesterol, and blood pressure tell you far more about your actual health status than your weight.

Practical Tips for Reaching and Maintaining a Healthy Weight

The research on long-term weight management consistently points to a small set of behaviors that compound over time.

Prioritize Protein and Strength Training

High protein intake (0.7–1 g per lb of body weight) combined with resistance training preserves and builds lean muscle while fat is lost. This improves body composition without necessarily changing the number on the scale dramatically — and it improves insulin sensitivity, bone density, and resting metabolic rate.

Focus on Sustainable Caloric Deficit, Not Crash Diets

A 300–500 calorie daily deficit produces 0.6–1 lb of fat loss per week without triggering the aggressive metabolic adaptation that comes with very low-calorie diets. Extreme restriction causes muscle loss and hormonal disruption that makes long-term weight maintenance harder.

Track Body Composition, Not Just Weight

Weight fluctuates by 2–5 lbs daily due to water retention, glycogen stores, and digestive contents. Body fat percentage, clothing fit, and progress photos are better progress indicators. Weigh yourself at the same time each morning, average weekly readings, and don’t react to day-to-day swings.

Sleep and Stress Management

Chronic sleep deprivation elevates ghrelin (hunger hormone) and suppresses leptin (satiety hormone), increasing caloric intake by an estimated 300–400 calories per day. High cortisol from chronic stress promotes abdominal fat storage even at maintenance calories. Neither sleep nor stress shows up in any weight formula.

Frequently Asked Questions

What is the ideal weight for a 5’10” male?

For a 5’10” male, estimates range from about 155 to 166 lbs across the four main formulas. Hamwi gives 166 lbs, Devine gives 160.9 lbs, Robinson gives 156.5 lbs, and Miller gives 154.9 lbs. A healthy BMI range of 18.5–24.9 for 5’10” corresponds to roughly 129–174 lbs — so most men in that height range have considerable room for healthy variation.

What is the ideal weight for a 5’5” female?

For a 5’5” female, the four formulas give estimates between 125 and 132 lbs: Hamwi gives 125 lbs, Devine gives 125.7 lbs, Robinson gives 126.8 lbs, and Miller gives 132.1 lbs. A BMI of 18.5–24.9 for 5’5” corresponds to approximately 111–150 lbs, a wide healthy range that accommodates different body types.

Is BMI the same as ideal body weight?

No. BMI is a ratio of weight to height squared, used as a population screening tool. Ideal body weight (IBW) formulas produce a single reference number based on height. Both are height-based proxies that ignore body composition, muscle mass, age, and frame size. A clinician might check both, but neither replaces a comprehensive health assessment. The WHO explicitly states BMI is a screening tool, not a diagnostic measure.

Which ideal weight formula is most accurate?

No single formula is most accurate for all people. The Devine formula is most common in clinical settings because it was widely adopted for drug dosing calculations. Robinson (1983) was designed as a Devine refinement with a shallower weight-per-inch slope. All formulas perform poorly for very tall individuals (above 6’2”) and for people with unusually high or low muscle mass. They’re reference points, not precise targets — use a range from all four as your reference window.

Can you be overweight on the scale but still healthy?

Yes. A landmark 2016 study in the International Journal of Obesityfound that BMI misclassifies about 54 million Americans as metabolically unhealthy when standard blood markers show they’re healthy. Athletes and strength-trained individuals often register as “overweight” or even “obese” by BMI because muscle tissue is denser than fat. Conversely, some people with a normal BMI are metabolically unhealthy due to high visceral fat. Weight is one data point, not a verdict.

How do I calculate my ideal weight without a calculator?

The easiest formula to do by hand is Hamwi. For men: start with 106 lbs for 5 feet and add 6 lbs per inch above 5 feet. For women: start with 100 lbs for 5 feet and add 5 lbs per inch above 5 feet. A 5’8” man: 106 + (8 × 6) = 154 lbs. A 5’3” woman: 100 + (3 × 5) = 115 lbs. Adjust ±10% for small or large frame size. For a more precise multi-formula comparison, use our Ideal Weight Calculator.