Ideal Weight Calculator

"What should I weigh?" It's one of the most common health questions. The answer isn't a single number—it's a range influenced by your height, body frame, sex, muscle mass, and age. Our Ideal Weight Calculator aggregates four validated medical formulas (Hamwi, Robinson, Miller, and Devine) to provide a comprehensive healthy weight target.

Ideal Weight Formulas Compared

Each formula was developed for a specific purpose (life insurance, clinical dosing, or general health). By comparing all four, you get a robust target range.

1. Hamwi Formula (1964) - For Insurance Underwriting

• Men: 106 lbs for first 5 feet + 6 lbs per additional inch
• Women: 100 lbs for first 5 feet + 5 lbs per additional inch
• Adjustments: Add 10% for large frame, subtract 10% for small frame
• Example: 5'10" man = 106 + (10 × 6) = 166 lbs base

2. Robinson Formula (1983) - Updated from Hamwi

• Men: 52 kg (115 lbs) for first 5 feet + 1.9 kg (4.2 lbs) per additional inch
• Women: 49 kg (108 lbs) for first 5 feet + 1.7 kg (3.7 lbs) per additional inch
• Generally 5-10 lbs lighter than Hamwi

3. Miller Formula (1983) - For Athletic Populations

• Men: 56.2 kg (124 lbs) for first 5 feet + 1.41 kg (3.1 lbs) per additional inch
• Women: 53.1 kg (117 lbs) for first 5 feet + 1.36 kg (3.0 lbs) per additional inch
• Yields lowest ideal weights of all formulas

4. Devine Formula (1974) - Drug Dosing Standard

• Men: 50 kg (110 lbs) for first 5 feet + 2.3 kg (5.1 lbs) per additional inch
• Women: 45.5 kg (100 lbs) for first 5 feet + 2.3 kg (5.1 lbs) per additional inch
• Still used to calculate medication dosages (e.g., Gentamicin, Theophylline)

Body Frame Size Adjustment

Your skeleton size affects your ideal weight. Measure your wrist circumference or elbow breadth to determine frame:

Wrist Measurement Method (Most Common):

• Men: Height >5'5": Wrist 6.5-7.5" = Medium frame. Smaller = small frame. Larger = large frame.
• Women: Height >5'5": Wrist 6.25-6.75" = Medium frame. Smaller = small frame. Larger = large frame.

Elbow Breadth Method (More Accurate):

1. Extend arm forward, bend elbow 90 degrees

2. Measure distance between humerus (outer elbow) and ulna (inner elbow)

3. Compare to frame size charts by height

Our calculator adjusts ideal weight by ±10% for small/large frames.

Ideal Weight vs Healthy BMI Range

The healthy BMI range (18.5-24.9) provides an alternative target. For a 5'6" (168 cm) person:

• BMI 18.5 = 115 lbs (52 kg)
• BMI 24.9 = 155 lbs (70 kg)
• Range = 40 lbs (18 kg)

Most ideal weight formulas fall in the middle of this range (for 5'6": ~130-140 lbs). This isn't a coincidence—formulas were calibrated to produce results consistent with BMI 21-22.

Ideal Weight for Athletes and Muscular Individuals

Standard ideal weight formulas assume average body composition. They will significantly under-estimate ideal weight for:

• Bodybuilders: A 5'10" bodybuilder at 200 lbs (90 kg) and 10% body fat has 180 lbs lean mass. His "ideal" per formula is 166 lbs—he'd need to lose muscle he doesn't have.
• Powerlifters: Heavier athletes in weight-class sports.
• Rugby/Football players: High muscle mass for position requirements.

If you have above-average muscle, ignore the ideal weight chart and focus on body fat percentage (men 10-18%, women 18-25%) and performance metrics.

Ideal Weight for Older Adults

After age 65, a slightly higher BMI (23-27) is associated with better health outcomes and lower mortality. The "obesity paradox" suggests some extra weight provides metabolic reserve during illness. Our calculator includes an "Age 65+" toggle that raises ideal weight targets by 5-10 lbs.

Setting Realistic Weight Goals

Your "ideal" weight might not be realistic or sustainable. Consider:

1. Lowest adult weight (maintained >1 year): Your body has a "set point" range. Losing below your historical low requires constant vigilance.

2. Weight at peak fitness: If you felt great at 160 lbs in college, that's more realistic than an ideal weight of 135 lbs you've never achieved.

3. Genetics and family history: Some ethnic groups (Polynesians, Pacific Islanders) have different body compositions.

4. Health markers over aesthetics: Normal blood pressure, cholesterol, blood sugar matter more than a specific number on the scale.

FAQ: Ideal Weight Calculator

Ideal Weight Calculator is optimized for fast browser-based use, so you can test multiple scenarios in seconds.