Ideal Weight Calculator — 4 Clinical Formulas + BMI (2026)

Your healthy weight range from the BMI 18.5–24.9 band plus four classic clinical formulas (Devine, Robinson, Miller, Hamwi) — shown side by side with their caveats. Free.

There is no single 'ideal' weight — there's a healthy range, and four decades-old clinical formulas that land at different points inside (and sometimes outside) it. Enter five details and see the full picture: the BMI-based range for your height, the four classic estimates, and where you stand today.

Why the formulas disagree

Devine (1974) was built for drug dosing, Hamwi (1964) for quick clinical estimation, and Robinson and Miller (1983) as refinements of Devine against actuarial data. None was designed as a health target — which is why they can spread 5+ kg apart for the same person and why we show all four instead of averaging away the disagreement.

The healthy-BMI band is the more defensible reference: it's the weight range associated with the lowest population-level health risk for your height. It's also wide — usually 15–20 kg — which is how much room individual healthy weights occupy.

What to do with the number

If you're inside the band: weight alone is a weak reason to change anything — energy, strength, labs, and habits tell you more. If you're outside it, direction matters more than distance: a sustained, modest change of even 5% of body weight measurably improves most health markers.

Set the eating side with tools that respect both the science and your life: the calorie-deficit calculator for the target, and the MyPlate Plan for what the target looks like as food.

Formula & sources

Devine (1974)

IBW={50.0+2.3 xmale45.5+2.3 xfemale\text{IBW} = \begin{cases} 50.0 + 2.3\,x & \text{male} \\[2pt] 45.5 + 2.3\,x & \text{female} \end{cases}

Robinson (1983)

IBW={52.0+1.9 xmale49.0+1.7 xfemale\text{IBW} = \begin{cases} 52.0 + 1.9\,x & \text{male} \\[2pt] 49.0 + 1.7\,x & \text{female} \end{cases}

Miller (1983)

IBW={56.2+1.41 xmale53.1+1.36 xfemale\text{IBW} = \begin{cases} 56.2 + 1.41\,x & \text{male} \\[2pt] 53.1 + 1.36\,x & \text{female} \end{cases}

Hamwi (1964)

IBW={48.0+2.7 xmale45.5+2.2 xfemale\text{IBW} = \begin{cases} 48.0 + 2.7\,x & \text{male} \\[2pt] 45.5 + 2.2\,x & \text{female} \end{cases}

Healthy-BMI weight band

weight range={18.5, 24.9}×[height (m)]2\text{weight range} = \{18.5,\ 24.9\} \times [\text{height (m)}]^2

IBW in kg; x = inches of height above 5 ft (60 in), and 0 for anyone shorter, so under 5 ft every formula gives its 5 ft value. The headline is the healthy-BMI band; the four clinical formulas are shown for comparison.

A realistic first goal

first goal={0.90, 0.95}×W\text{first goal} = \{0.90,\ 0.95\} \times W

W = current weight. 5 to 10% under it, shown when the current weight is above the healthy-BMI band.

Adjusted body weight

AdjBW=IBW+0.25 (W−IBW)\text{AdjBW} = \text{IBW} + 0.25\,(W - \text{IBW})

IBW by the Hamwi formula above, W = current weight, both in kg to one decimal. Shown when the current weight is above the healthy-BMI band.

Sources

  • Jensen MD, Ryan DH, Apovian CM, et al. (2014) 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults. Circulation 129(25 Suppl 2):S102–S138. The first goal: a loss of 5 to 10% of baseline weight within 6 months.
  • Karkeck J (1984) Adjusted body weight for obesity. American Dietetic Association Renal Dietitians Practice Group Newsletter 3:6. The origin of the 25% factor.
  • Krenitsky J (2005) Adjusted body weight, pro: evidence to support the use of adjusted body weight in calculating calorie requirements. Nutr Clin Pract 20(4):468–473.
  • Devine BJ (1974) Gentamicin therapy. Drug Intell Clin Pharm 8:650–655.
  • Robinson JD, et al. (1983) Determination of ideal body weight for drug dosage calculations. Am J Hosp Pharm 40(6):1016–1019.
  • Miller DR, Carlson JD, Lloyd BJ, Day BJ (1983) Determining ideal body weight (and mass). Am J Hosp Pharm 40(10):1622-1627.
  • Hamwi GJ (1964) Therapy: changing dietary concepts. In: Diabetes Mellitus: Diagnosis and Treatment. American Diabetes Association.

Ideal weight questions, answered

What is my ideal weight for my height?

A range, not a number: the weights that give a BMI of 18.5 to 24.9 at your height, and this page computes yours. From 5 ft to 7 ft (152 to 213 cm), the four clinical formulas each land at one point inside that band; shorter or much taller, some can fall outside it. They disagree because of how each was built, not because of your body.

Which ideal-weight formula is most accurate?

None is 'accurate' as a health target — Devine was built for drug dosing, Hamwi for bedside estimation. They're shown because they're widely quoted; the BMI band is the better-evidenced reference for population health.

Is BMI reliable for me?

It's a screening tool with known blind spots: it can't distinguish muscle from fat, so muscular people often read 'above range' at healthy body-fat levels, and it under-flags low muscle mass in older adults. Waist measurements and body composition tell richer stories.

How fast can I reach a healthy weight safely?

The conventional sustainable rate is 0.25–0.5 kg (0.5–1 lb) per week — a 250–500 kcal/day deficit. Our calorie-deficit calculator builds the targets with below-BMR warnings included.

Does age change my ideal weight?

The BMI band is defined for adults generally, but evidence suggests slightly higher BMIs are not harmful — and may be protective — in older adults. After ~65, preserving muscle matters more than chasing the lower half of the range.

Do I need to hit the middle of the range?

No. Anywhere inside the band carries similar population-level risk, and your healthiest weight within it depends on build, history, and what you can maintain while living well. The middle is a statistic, not a prescription.

What is a realistic goal weight?

Start with 5 to 10% of what you weigh today. The 2013 U.S. obesity guideline sets that as the first goal, over about six months, and this page works it out for you when your weight is above the healthy range. Reach it, hold it, then set the next one.

What is adjusted body weight?

Your ideal weight plus 25% of the weight above it. Hospitals use it for feeding plans at higher weights and for some medicine doses, and some dietitians use it as a nearer goal weight. The adjusted body weight calculator shows the sum with your numbers.

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