CalcIdeal Weight Calculator
Calculate your ideal weight for your height using Lorentz and Devine formulas.
What is Ideal Weight Calculator?
The Ideal Weight Calculator estimates a healthy body weight range based on your height, gender, and body frame size using multiple established medical formulas. Unlike BMI, which only categorizes your current weight status, ideal weight calculators provide target ranges to aim for. The four most commonly used formulas are the Devine formula (most widely used for medical dosing), Robinson formula (modified for broader populations), Miller formula (based on body surface area), and Hamwi method (commonly used in clinical nutrition). For a 5'6" woman, these formulas typically suggest 120-140 lbs as ideal; for a 5'10" man, 150-175 lbs. However, "ideal" varies significantly based on muscle mass, bone density, age, and individual health factors. This calculator provides multiple formula results so you can see the range and discuss realistic targets with your healthcare provider rather than fixating on a single number.
How Ideal Weight Calculator Works: The Formulas Explained
Each ideal weight formula uses height as the primary variable, with adjustments for gender and sometimes frame size. Devine Formula (1974): Most commonly used in medical settings for drug dosing. For men: 50 kg + 2.3 kg per inch over 5 feet. For women: 45.5 kg + 2.3 kg per inch over 5 feet. Example: A 5'8" man = 50 + (2.3 × 8) = 68.4 kg = 150.5 lbs. Robinson Formula (1983): Modified to be slightly more inclusive. Men: 52 kg + 1.9 kg per inch over 5 feet. Women: 49 kg + 1.7 kg per inch over 5 feet. Miller Formula (1983): Based on body surface area research. Men: 56.2 kg + 1.41 kg per inch over 5 feet. Women: 53.1 kg + 1.36 kg per inch over 5 feet. Hamwi Method (1964): Originally designed for diabetes management, includes frame size adjustments. Men: 106 lbs for first 5 feet + 6 lbs per additional inch. Women: 100 lbs for first 5 feet + 5 lbs per additional inch. Add or subtract 10% for large or small frame sizes respectively.
Step-by-Step Guide to Using This Calculator
- Enter your gender: Select male or female — all formulas use different base weights and adjustment factors for each gender due to differences in bone density and typical muscle mass.
- Enter your height: Input in feet/inches or centimeters. Be precise — each additional inch adds 4-6 lbs to the ideal weight calculation. If you're between heights (e.g., 5'7.5"), round to the nearest inch or enter both to see the range.
- Select your frame size (if available): Measure your wrist circumference to determine frame: Small (women: <5.5", men: <6.5"), Medium (women: 5.5-6.5", men: 6.5-7.5"), Large (women: >6.5", men: >7.5"). Frame size can shift your ideal weight by ±10% — a 10-lb difference for someone with a 100-lb ideal weight.
- Review results from all formulas: The calculator displays results from Devine, Robinson, Miller, and Hamwi formulas. Expect a range of 10-20 lbs between formulas — this variation is normal and shows why no single number is definitive.
- Consider your individual context: Compare the calculated range to your current weight, body composition, and health markers. A physically active person with high muscle mass may be healthy well above the "ideal" range, while someone with low muscle mass may need to focus on body composition rather than scale weight alone.
Real-World Examples
Example 1 — Average Height Woman: A 5'4" woman with medium frame. Devine: 45.5 + (2.3 × 4) = 54.7 kg = 120.6 lbs. Robinson: 49 + (1.7 × 4) = 55.8 kg = 123 lbs. Miller: 53.1 + (1.36 × 4) = 58.5 kg = 129 lbs. Hamwi: 100 + (5 × 4) = 120 lbs. Range: 120-129 lbs. At 5'4", the BMI healthy range (18.5-24.9) translates to 107-145 lbs — wider than the formula recommendations. If she currently weighs 145 lbs at 25% body fat, losing 20 lbs to reach 125 lbs would likely improve health markers. If she weighs 145 lbs at 18% body fat (athletic build), the "ideal weight" may be less relevant than maintaining her current composition.
Example 2 — Tall Man with Large Frame: A 6'2" man with large frame. Devine: 50 + (2.3 × 14) = 82.2 kg = 181 lbs. Robinson: 52 + (1.9 × 14) = 78.6 kg = 173 lbs. Miller: 56.2 + (1.41 × 14) = 75.9 kg = 167 lbs. Hamwi: 106 + (6 × 14) = 190 lbs, +10% for large frame = 209 lbs. Range: 167-209 lbs — a 42-lb spread showing why frame size matters. The Hamwi method with frame adjustment is most appropriate here. At 6'2" with a large frame, 175 lbs (Devine) might actually be underweight for his bone structure, while 195 lbs could be ideal.
Example 3 — Weight Loss Goal Setting: A 5'6" woman weighs 180 lbs and wants a realistic target. Formulas suggest 130-145 lbs. Losing 35-50 lbs is a 19-28% reduction — medically significant and likely to improve blood pressure, blood sugar, and joint pain. However, losing to 135 lbs (25% loss) may be more realistic than 130 lbs (28% loss). Research shows 5-10% weight loss provides substantial health benefits. Her first milestone: 162 lbs (10% loss), which already improves metabolic health. The ideal weight is a direction, not a pass/fail threshold.
Common Mistakes to Avoid
- Treating ideal weight as a single target: All formulas produce estimates, not prescriptions. The 15-20 lb range between formulas represents genuine medical uncertainty about what weight is "ideal" for any individual. Focus on the range, not a specific number. Someone told their ideal is 145 lbs may struggle unnecessarily when 150 lbs is equally healthy.
- Ignoring body composition: Two people can weigh 160 lbs at 5'8" — one with 12% body fat (muscular, metabolically healthy) and one with 30% body fat (high visceral fat, insulin resistant). The muscular person may be labeled "overweight" by ideal weight formulas despite being healthier. Waist circumference, body fat percentage, and blood work matter more than the scale alone.
- Using ideal weight for children or teens: These formulas were developed for adults and don't account for growth patterns, puberty, or developing bone structure. Children should use BMI percentiles adjusted for age and sex, not adult ideal weight formulas. A 14-year-old at 5'6" is still growing — their healthy weight at 18 may be 20 lbs higher than current calculations suggest.
- Comparing yourself to others at the same height: Your ideal weight depends on YOUR frame size, muscle mass, age, and health history — not your friend's weight or celebrity heights/weights. Two 5'5" women can have legitimately different ideal weights if one has a small frame (wrist <5.5") and one has a large frame (wrist >6.5"). That's a 12-15 lb difference explained by bone structure alone.
Pro Tips for Better Results
- Measure your wrist for frame size: Wrap a flexible measuring tape around your dominant wrist just below the styloid process (the bony bump). Women: <5.5" = small, 5.5-6.5" = medium, >6.5" = large. Men: <6.5" = small, 6.5-7.5" = medium, >7.5" = large. This simple measurement adjusts your ideal weight by ±10% and explains why you may naturally weigh more or less than someone the same height.
- Use ideal weight as one data point among many: Track waist circumference (<35" women, <40" men), resting heart rate (60-100 bpm, lower is better for athletes), blood pressure (<120/80), fasting glucose (<100 mg/dL), and how your clothes fit. Someone at the top of their ideal weight range with excellent markers is healthier than someone at the bottom with poor markers.
- Set milestone goals, not just endpoint goals: If you're 190 lbs and your ideal is 150 lbs, don't fixate on the 40-lb gap. Set 5-lb milestones: 185, 180, 175... Each 5-lb loss produces measurable health improvements. Celebrate reaching 170 lbs (10% loss) as a major victory — you've already reduced diabetes risk by 30-40% at this point, even if you haven't reached "ideal."
- Adjust expectations for age: Ideal weight formulas don't account for age-related muscle loss (sarcopenia). Adults over 50 may find their "ideal" weight is 5-10 lbs higher than formulas suggest because they need reserve muscle mass. A 60-year-old at 10% above ideal weight with good strength has better survival odds than the same person at exactly ideal weight with frailty. Focus on maintaining muscle through resistance training, not just hitting a number.
Frequently Asked Questions
Which ideal weight formula is most accurate?
No single formula is universally "most accurate" — they were developed for different purposes. Devine is best validated for medical drug dosing and is most commonly used in hospitals. Hamwi is preferred in nutrition counseling and includes frame size adjustments. Robinson and Miller were developed to address limitations in earlier formulas for broader populations. Research comparing all four shows they correlate similarly with health outcomes, so the best approach is to look at the range all formulas produce. If Devine says 150 lbs, Robinson says 147 lbs, and Hamwi says 155 lbs, your personal ideal is likely somewhere in the 147-155 lb range. Use the average or midpoint as a target, understanding ±5 lbs is equally healthy.
Should I aim for the low end or high end of my ideal weight range?
Current research suggests the high end of ideal weight (or even 10-15 lbs above) may be protective for adults over 40. Multiple large studies show adults with BMI 25-27 (slightly "overweight" by standard definitions) have equal or lower mortality than those with BMI 18.5-22 (low "normal"). This "obesity paradox" may reflect that extra weight provides metabolic reserve during illness. For adults under 40, the middle of the range is reasonable. For adults 40-60, the middle to high end is appropriate. For adults over 60, being at the high end or slightly above (BMI 25-27) is associated with better survival. Muscle mass matters more than weight at any age — prioritize strength training over scale numbers.
How does muscle mass affect ideal weight calculations?
Ideal weight formulas cannot distinguish muscle from fat — they assume average body composition. A 5'10" male bodybuilder weighing 195 lbs at 10% body fat is classified as "30 lbs over ideal" by Devine (165 lbs), but he's actually healthier than a sedentary person at 165 lbs with 25% body fat. Muscle is denser than fat (takes less space per pound) and metabolically active (burns more calories at rest). If you lift weights regularly, have visible muscle definition, or work in a physical job, your healthy weight may be 15-25 lbs above formula recommendations. Use body fat percentage (men: 10-20%, women: 18-28%) and waist circumference as better health indicators than weight alone.
What if my current weight is far above my ideal weight?
First, understand that 5-10% weight loss provides substantial health benefits even if you don't reach "ideal." Someone weighing 250 lbs with an ideal of 170 lbs doesn't need to lose 80 lbs to improve health — losing 25 lbs (10%) significantly reduces blood pressure, blood sugar, inflammation, and joint pain. Second, focus on behaviors, not the endpoint: consistent nutrition, regular movement, adequate sleep, and stress management. These produce sustainable weight loss regardless of starting point. Third, consider that your personal healthy weight may differ from formula predictions — discuss with your doctor whether 190 lbs with excellent blood work is an acceptable goal versus struggling to reach 170 lbs. Health is multidimensional; weight is one factor among many.
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See also: BMI Calculator, Body Fat Percentage Calculator, Daily Calorie Calculator, Waist-to-Hip Ratio Calculator
Related calculators: BMI Calculator (Body Mass Index) · Healthy Weight Range Calculator · Daily Calorie Calculator (TDEE)