Ideal Weight Guide 2026: Formulas, Frames and Healthy Ranges
Table of Contents
The Classic Formulas
5'10" man: 50 + 2.3x10 = 73 kg = 161 lb. 5'5" woman: 45.5 + 2.3x5 = 57 kg = 126 lb.
Robinson and Miller formulas adjust slightly; Hamwi (used clinically for drug dosing) gives similar results. All were designed for medication dosing, not aesthetics - treat them as reference points.
Formula comparison for a 5'10" man — Devine: 161 lb; Robinson (52 + 1.9 x 10 = 71 kg): 156 lb; Miller (56.2 + 1.41 x 10 = 70.3 kg): 155 lb; Hamwi (106 + 6 x 10): 166 lb. An 11-lb spread from formulas answering the same question — because they were built for drug dosing, where "close enough" is calibrated differently than aesthetics. Treat any single output as ±5 lb and you'll never be misled by false precision.
The clinical use case, since it's the real one: chemotherapy and anesthesia dose from ideal or adjusted body weight, not actual — for obese patients, adjusted = IBW + 0.4 x (actual - IBW). A 250-lb man with IBW 161: adjusted = 161 + 0.4 x 89 = 197 lb dosing weight. This is the formulas' actual job; your mirror was never the intended audience.
Frame Size Adjustments
Measure wrist circumference to gauge frame:
| Frame | Men (wrist) | Women (wrist) | Adjustment |
|---|---|---|---|
| Small | Under 6.5" | Under 5.75" | -10% |
| Medium | 6.5-7.5" | 5.75-6.25" | Base |
| Large | Over 7.5" | Over 6.25" | +10% |
Large-framed 5'10" man: 161 x 1.10 = 177 lb - a 16-lb swing from frame alone.
Elbow breadth is the alternative frame test: extend the arm, measure across the elbow — men over 2.75", women over 2.5" suggest large frames. Or the height/wrist ratio: height ÷ wrist in inches — men >10.4 = small, 9.6-10.4 = medium, <9.6 = large (women: >11 = small, 10.1-11 = medium, <10.1 = large). A 5'10" (70") man with a 6.5" wrist: ratio 10.8 = small frame — his 161-lb Devine target stands unadjusted, no +10% for him.
Muscle overrides frame: a lifter with 2+ years of training adds 10-15% over formula weight — our large-framed 177-lb example becomes ~195-200 lb lean. Cross-check with FFMI: if the formula weight implies FFMI under 20 for a trained man, the formula is underweighting his muscle. Formulas describe skeletons; training builds the house, and the house weighs more.
BMI Range: The Saner Target
Convert the healthy BMI range (18.5-24.9) to weight for your height:
5'10" (1.78m): 18.5 x 3.17 = 129 lb to 24.9 x 3.17 = 174 lb. Range: 129-174 lb.
Ranges beat single numbers - healthy weight varies with muscle, age, and build. Aim for the range, then refine by waist, body fat, and how you feel.
Second height worked: 5'5" (1.65 m, 2.7225 m²): 18.5 x 2.7225 = 50.4 kg = 111 lb; 24.9 x 2.7225 = 67.8 kg = 149 lb. Range: 111-149 lb — a 38-lb span that embarrasses single-number formulas. Note the bottom: 111 lb at 5'5" suits almost no adult woman with muscle; most feel and perform best in the upper-middle of their range, which is exactly what ranges (not points) are for.
The mortality U-curve: large cohorts find lowest all-cause mortality around BMI 22-25, rising below 20 and above 27-30 — but the curve shifts right with muscle and age. Athletes sit healthily at 26-27; adults over 65 at 24-28. "Ideal" is a range with a personal sweet spot, found via waist, energy, bloodwork, and strength — not via a formula's decimal.
Setting a Realistic Goal Weight
- Start from your BMI range, adjusted for frame and muscle.
- Consider your weight history - maintaining near your adult baseline is easier than chasing high-school weight.
- Set process goals (training, protein, sleep) alongside outcome goals.
- Reassess every 10 lb - body composition changes the target.
- Talk to your doctor about medications or conditions affecting weight.
Respect the set point: the body defends a ~10-15 lb range via hunger hormones — a 220-lb adult targeting 150 fights biology the whole way, while targeting 198-208 (5-10% loss) works with it and still transforms health markers (diabetes risk −50%+ at 7% loss in the DPP trial). Stage the goal: lose 10%, stabilize 3 months, then decide if another 10% is worth it. Staircases beat cliffs.
Timeline honesty: 1 lb/week = 20 lb in 20 weeks, plus 2 diet breaks = ~26 weeks — six months, not six weeks. SMART-framed: "Reach 195 lb by April (0.8 lb/week) via 2,200 cal/day, 4 lifts/week, 8k steps" beats "lose weight" the way a map beats a wish. Reassess every 10 lb: body composition, hunger, and labs may move the target — the goal weight is a hypothesis, not a contract.
Frequently Asked Questions
A range, not a number: the healthy BMI range for your height, adjusted for frame size and muscle mass. Formulas give starting estimates.
Devine is the clinical standard (drug dosing). Robinson fits modern populations slightly better. All are approximations - ranges matter more.
Formulas don't adjust, but healthy body composition shifts - slightly higher weight with maintained muscle is fine and protective in older age.
They assume average frames and modest muscle. Muscular, large-framed, or tall people healthily exceed formula weights - check waist and body fat %.
It's a rough Hamwi simplification - decent for women of average frame, less so for men or athletes. Use proper formulas for better estimates.