Ideal Weight Calculator
Five formulas, one chart. See where the medical literature actually places your "ideal" — and how much they disagree.
An ideal weight calculator estimates a healthy target weight using clinical formulas (Devine, Robinson, Miller, Hamwi) and the modern healthy-BMI range (18.5–24.9, midpoint BMI 22). We adjust ±10% for small or large frame size.
Now turn the number into action
A calculator gives you a target. A tracker tells you whether you're actually hitting it. These are the three we recommend — Welling first, because it's the only one that goes beyond logging.
Welling
Doesn't just log food — it coaches. Welling pairs effortless calorie and macro tracking with an AI coach that reads your data, flags patterns (under-eating protein, weekend over-shoots, plateau windows), and adjusts your plan. The best fit for anyone who wants the math and the accountability.
MacroFactor
The most accurate auto-adjusting calorie target on the market. MacroFactor recalculates your expenditure weekly from your actual weight trend and food log — so when adaptive thermogenesis kicks in, your target shifts before the scale stalls. Best for serious dieters who want hands-off precision.
MyFitnessPal
The most well-known calorie tracker, with the biggest food database (millions of crowd-sourced entries). Easy to use, free tier covers the basics, and barcode-scanning is fast. Trade-off: entries vary in accuracy — verify generic foods against USDA values when precision matters.
Further reading: round-ups of AI calorie trackers, food trackers, and calorie counters.
How ideal body weight is calculated
Five different formulas. Each was developed for a slightly different purpose — most originated in the 1960s–80s for drug dosing — and they disagree by 5–15 lbs at any given height.
Devine (1974) — the medical default
Women: IBW (kg) = 45.5 + 2.3 × (height inches − 60)
Robinson (1983)
Women: IBW (kg) = 49 + 1.7 × (height inches − 60)
Miller (1983)
Women: IBW (kg) = 53.1 + 1.36 × (height inches − 60)
Hamwi (1964) — quick clinical estimate
Women: IBW (lb) = 100 + 5 × (height inches − 60)
Healthy BMI range — the modern anchor
Upper bound (kg) = 24.9 × (height m)²
Midpoint (BMI 22) = 22 × (height m)²
Frame size adjustment
- Small frame — subtract 10%
- Medium frame — no adjustment
- Large frame — add 10%
Why ideal-weight calculations are useful
- It anchors a long-term goal. "I want to lose weight" is vague. "I'd like to be around 145 lb (BMI 22)" is concrete and trackable.
- It tempers aspirational thinking. Going below the formulas' range without ample lean mass usually means losing muscle, not just fat.
- It checks against social comparisons. Body weight depicted on social media often falls well below clinical ideal-weight ranges. The math is a useful reality check.
- It informs medical dosing. Many drug dosages (especially in hospitals) are calculated using Devine IBW. Knowing yours is occasionally useful.
- It pairs with body composition. Combine an IBW target with a body-fat goal — e.g., "BMI 22 at 18% body fat" — and you'll know how much should be muscle.
FAQ
What is 'ideal' body weight?
There's no single ideal weight — there's a healthy range. The clinical 'ideal body weight' (IBW) formulas (Devine, Robinson, Miller, Hamwi) were originally developed in the 1960s–80s for drug dosing, not aesthetics. Use them as one reference among several.
Which IBW formula is most accurate?
None is consistently 'best'. Devine is the most widely used in medicine. Robinson and Miller produce slightly lower values. The healthy-BMI range (18.5–24.9) is a more modern, evidence-based target.
How does frame size affect ideal weight?
Larger frame = more bone and lean mass at the same height. We adjust the IBW formulas by ±10% for small vs. large frames. To estimate frame size, measure wrist circumference relative to height.
Is BMI 22 the perfect target?
BMI 22 sits roughly in the middle of the WHO healthy band and aligns with the lowest all-cause mortality in large cohort studies. It's a reasonable long-term anchor for non-athletes, but body composition matters more than weight.
What if I have a lot of muscle?
All of these formulas — including BMI-based — will underestimate your healthy weight. For athletes and lifters, body fat percentage and waist-to-height ratio are better individual targets.
Sources
- Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650–55.
- Robinson JD, et al. Determination of ideal body weight for drug dosage calculations. Am J Hosp Pharm. 1983;40(6):1016–9.
- Miller DR, et al. Predicting theophylline clearance in normal adults. Drug Intell Clin Pharm. 1983;17(2):129–32.
- Hamwi GJ. Therapy: Changing dietary concepts. In: Diabetes Mellitus. 1964;73–8.