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Ideal Weight Calculator: Estimate Your Reference Weight

An ideal weight calculator estimates a reference body weight based on your height and sex, using formulas originally developed for clinical and medical use. It’s not a single “correct” number so much as a useful target range, one that four different, well-established formulas each estimate slightly differently. Below, we’ll cover how those formulas work, how they compare to each other and to BMI, and what their real limitations are.

Quick answer: For a man at 5’10” (178 cm), ideal weight estimates range from about 70 to 75 kg (155–165 lbs) depending on the formula used. For a woman at 5’4″ (163 cm), estimates range from about 54 to 59 kg (120–129 lbs). This calculator compares four established ideal-body-weight formulas: Devine, Hamwi, Robinson, and Miller.

What Is an Ideal Weight Calculator?

An ideal weight calculator estimates your Ideal Body Weight (IBW): a reference weight based on your height and sex. Several widely used IBW formulas originated in clinical or height-weight reference work and were later applied to medication dosing and other medical calculations. Over time, they’ve been adopted more broadly as a general reference point for healthy weight.

This calculator uses four separate formulas—Devine, Hamwi, Robinson, and Miller—because no single one is “the” correct answer. Each was developed in a different decade for a slightly different purpose, so seeing all four side by side gives you a more honest picture than any one number alone.

Why It Matters

A single ideal weight number can feel authoritative, but it’s really just an estimate based on population averages from decades ago. Knowing that up front changes how useful the number actually is. It’s less a target to hit exactly and more a general reference point to weigh against your own body, health markers, and goals.

That context matters because these formulas are still genuinely useful. Pharmacists use versions of them today to dose medications safely, and they remain a reasonable starting point for general weight discussions. They’re just not the final word on what your weight “should” be.

How the Calculator Works: Ideal Weight Formulas Explained

All four formulas follow the same basic structure: a base weight at 5 feet tall, plus a fixed amount added for every inch above that. They differ in their starting point and their per-inch increment.

• Devine (1974)—Men: 50 kg + 2.3 kg per inch over 5 feet. Women: 45.5 kg + 2.3 kg per inch over 5 feet. Dr. B.J. Devine originally published this for calculating drug dosages, and it’s since become the most widely cited IBW formula in clinical practice.
• Hamwi (1964)—Men: 48 kg + 2.7 kg per inch over 5 feet. Women: 45.5 kg + 2.2 kg per inch over 5 feet. The oldest of the four was developed by Dr. George Hamwi as a quick reference for dietitians and diabetes management.
• Robinson (1983)—Men: 52 kg + 1.9 kg per inch over 5 feet. Women: 49 kg + 1.7 kg per inch over 5 feet. A later refinement of Devine’s formula, also developed for pharmacy dosing calculations.
• Miller (1983)—Men: 56.2 kg + 1.41 kg per inch over 5 feet. Women: 53.1 kg + 1.36 kg per inch over 5 feet. Published the same year as Robinson, using a higher base weight but a smaller per-inch increment.

Worked example, using a 5’10” (178 cm) man and a 5’4″ (163 cm) woman:

Formula	Male (5’10”)	Female (5’4″)
Devine (1974)	73.0 kg (161 lbs)	54.7 kg (121 lbs)
Hamwi (1964)	75.0 kg (165 lbs)	54.3 kg (120 lbs)
Robinson (1983)	71.0 kg (157 lbs)	55.8 kg (123 lbs)
Miller (1983)	70.3 kg (155 lbs)	58.5 kg (129 lbs)

Notice the spread: roughly 5 kg (11 lbs) between the highest and lowest estimate for the same person. That’s normal. It’s exactly why this calculator shows a range instead of pretending one formula has the definitive answer.

How to Use This Calculator

1. Select your sex and enter your height.
2. Choose a formula, or review results across all four for a fuller picture.
3. Optionally enter your current weight to see how it compares.
4. Treat the result as a reference band, not a strict target to hit exactly.

Understanding Your Results

Your result is a reference weight, not a verdict. If your current weight sits above or below the estimate, that’s genuinely common. These formulas were built from population averages, and none of them account for your individual muscle mass, bone density, or body frame.

What’s more useful than chasing an exact number is looking at the direction and the range. If your weight sits noticeably outside all four formulas’ estimates, that’s worth understanding through more informative measures. Your BMI Calculator result or your Body Fat Calculator result, can add useful context beyond the IBW number alone.

Ideal Weight vs. BMI

These two tools answer related but different questions. Ideal weight formulas give you a specific weight in kg or lbs based on height and sex. BMI gives you a category—underweight, normal, overweight, or obese—based on weight relative to height, without directly outputting a target weight.

BMI is generally considered the more modern, widely used reference for general health screening, while IBW formulas remain more common in specific clinical contexts, like medication dosing. Neither accounts for body composition, so pairing either one with your Body Fat Calculator result gives a fuller picture than relying on just one number.

Factors That Affect Ideal Weight & Limitations

A few things these formulas don’t account for, by design:

• Muscle mass—none of the four formulas know how much of your weight is muscle versus fat, so muscular people and athletes often land above their “ideal” weight despite being lean and healthy
• Bone density and body frame—naturally larger or smaller frames aren’t reflected in a formula based only on height and sex
• Age-related changes—body composition shifts with age, but these formulas were developed primarily from adult population data and don’t adjust for it
• Ethnicity—the original data behind these formulas came from specific population groups, which may not generalize evenly across all backgrounds

A few honest limitations worth stating directly: these formulas aren’t suitable for pregnant or lactating women, and they were developed for adults 18 and older, not children or teens. They’re a reference point built from height and sex alone; useful, but genuinely limited compared to a fuller body composition assessment.

Tips for Reaching or Maintaining a Healthy Weight

If you’re using your result as a general direction rather than a strict target, a few things help:

• Set your calorie target from your actual goal, not from the IBW gap. Our Calorie Calculator can help you find a sustainable number based on your body and activity level, rather than trying to close an IBW gap quickly.
• Build or maintain muscle through resistance training. Since these formulas don’t account for muscle, focusing on body composition rather than the scale alone often serves you better.
• Track trends, not single readings. Weight fluctuates day to day; what matters is the direction over weeks and months.
• Use the range, not a single number, as your reference. Given how much the four formulas can differ, aiming for “somewhere in this band” is more realistic than chasing one exact figure.

Common Mistakes & Misconceptions

• Treating the result as a strict target to hit exactly. These formulas produce a reference range, not a precise goal; the 5 kg spread between the formulas above makes that clear.
• Assuming one formula is “more correct” than the others. Each was developed for a specific clinical purpose in a different era. None is definitively more accurate for general use than the others.
• Applying it to athletes or very muscular people without adjustment. Since muscle mass isn’t factored in, these formulas often underestimate a healthy weight for people with significant muscle.
• Using it during pregnancy or lactation. These formulas weren’t developed for that context and shouldn’t be used to set weight goals during it.

When to Consult a Doctor

An ideal weight calculator gives you a reference point, not medical guidance. Talk to a doctor if:

• Your weight is changing significantly without a clear reason
• You’re pregnant or breastfeeding and want guidance on healthy weight during that time
• You’re an athlete or very muscular and want a more meaningful assessment than height-and-sex formulas can offer
• You have concerns about your weight that these general formulas don’t address

Frequently Asked Questions

What is an ideal weight calculator?

An ideal weight calculator estimates a reference body weight based on your height and sex, using formulas originally developed for clinical use, like medication dosing.

Is ideal weight the same as BMI?

No. Ideal weight formulas give you a specific target weight based on height and sex. BMI gives you a category based on weight relative to height. They’re related concepts but calculated differently.

Which ideal weight formula is most accurate?

None of the four is definitively more accurate than the others for general use. They were developed for different clinical purposes in different decades and typically land within about 5 kg of each other for the same height.

Can athletes use ideal weight calculators?

Athletes can use them, but the results are often less meaningful, since none of the four formulas account for muscle mass. A muscular athlete frequently weighs more than their “ideal” weight while being lean and healthy.

Does age affect ideal weight?

These formulas don’t adjust for age directly, even though body composition naturally changes over time. They were developed primarily from adult population data and apply to adults 18 and older.

How accurate are ideal weight calculators?

They’re reasonable reference points, not precise measurements. Since the four established formulas can differ by several kilograms for the same person, treat any single result as an estimate within a range, not an exact number.

Can I be healthy if I’m above my ideal weight?

Yes. These formulas don’t account for muscle mass, bone density, or overall health markers. Being above a formula’s estimate doesn’t automatically mean anything is wrong, especially if your fitness, energy, and health metrics are otherwise good.

What is ideal body weight (IBW)?

Ideal Body Weight is a reference weight calculated from height and sex. It was originally developed to support clinical calculations like medication dosing and is now more broadly used as a general weight reference point.

Related Calculators

• BMI Calculator
• BMR Calculator
• Body Fat Calculator
• Calorie Calculator
• Waist to Hip Ratio Calculator
• Lean Body Mass Calculator

Key Takeaways

• Ideal weight calculators estimate a reference weight from height and sex, originally built for clinical uses like medication dosing.
• This calculator uses four established formulas—Devine (1974), Hamwi (1964), Robinson (1983), and Miller (1983)—which can differ by several kilograms for the same person.
• None of the four formulas account for muscle mass, bone density, age-related changes, or ethnicity.
• Ideal weight and BMI measure related but different things; neither accounts for body composition on its own.
• Treat your result as a reference range, not a strict target—especially if you’re an athlete, pregnant, or breastfeeding.

References

• Hamwi GJ. Ideal body weight formula. In: Diabetes Mellitus: Diagnosis and Treatment. 1964.
• Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650–655.
• Robinson JD, Lupkiewicz SM, et al. Determination of ideal body weight for drug dosage calculations. Am J Hosp Pharm. 1983;40(6):1016–1017.
• Miller DR, Carlson JD, et al. Determination of ideal body weight. Clin Pharm. 1983;2(6):506–508.

Medical Disclaimer

This calculator and article provide general estimates for informational purposes only and are not a substitute for professional medical advice. Medication dosing is drug-specific and may use actual body weight, ideal body weight, adjusted body weight, lean body weight, or another dosing method depending on the medication and clinical situation. Consult a doctor or registered dietitian for guidance specific to your health.

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Written by: Suvojit Datta, M.Pharm
Last reviewed: August 2026