OnlineCalculatorYour ideal weight for height and age depends on several factors beyond a single number on a scale. According to the World Health Organization (WHO), a healthy Body Mass Index (BMI) falls between 18.5 and 24.9 for most adults worldwide. However, BMI alone misses roughly 30% of people with unhealthy body fat levels because it cannot distinguish muscle from fat. Your bone structure, muscle mass, sex, and age all shift what "healthy" actually means for you. This guide breaks down the proven formulas, official charts, and practical factors that determine your personal healthy weight range — so you can stop guessing and start knowing.
What Is Ideal Weight for Height and Age?
Ideal body weight is a clinically estimated range — not a single magic number — considered healthy for your height, age, and sex. Doctors and dietitians use it as a screening baseline, not a final diagnosis. The concept dates back to 1943 when Metropolitan Life Insurance published its first height-weight tables based on mortality data.
The key word is range. A 5'7" (170 cm) adult male might have a healthy weight anywhere from 133 to 163 lbs (60 to 74 kg). That 30-pound spread exists because two people of identical height can have very different body compositions. Age matters too — adults naturally gain 1 to 2 lbs per year after age 30 as metabolism gradually slows.
No single formula works for everyone. The WHO, CDC, and NIH all recommend using BMI as a starting point, then factoring in waist circumference, body fat percentage, and individual health markers for a complete picture.
How Ideal Weight Is Calculated
Medical professionals rely on several formulas to estimate healthy weight. Each has strengths and blind spots. Here are the most widely used methods:
- BMI Formula: Weight (kg) ÷ Height (m²). A BMI of 18.5–24.9 is classified as normal weight by the WHO.
- Devine Formula (1974): Used in clinical drug dosing. Males: 50 kg + 2.3 kg per inch over 5 feet. Females: 45.5 kg + 2.3 kg per inch over 5 feet.
- Robinson Formula (1983): Males: 52 kg + 1.9 kg per inch over 5 feet. Females: 49 kg + 1.7 kg per inch over 5 feet.
- Miller Formula (1983): Males: 56.2 kg + 1.41 kg per inch over 5 feet. Females: 53.1 kg + 1.36 kg per inch over 5 feet.
- Hamwi Formula (1964): Males: 48 kg + 2.7 kg per inch over 5 feet. Females: 45.5 kg + 2.2 kg per inch over 5 feet.
Comparison Table: Ideal Weight Estimates for 5'7" (170 cm) Adults
| Formula | Male (lbs / kg) | Female (lbs / kg) |
|---|---|---|
| Devine | 154 lbs / 69.9 kg | 139 lbs / 63.1 kg |
| Robinson | 150 lbs / 68.0 kg | 137 lbs / 62.2 kg |
| Miller | 156 lbs / 70.8 kg | 140 lbs / 63.5 kg |
| Hamwi | 159 lbs / 72.1 kg | 143 lbs / 64.9 kg |
| BMI Midpoint (21.7) | 152 lbs / 69.0 kg | 152 lbs / 69.0 kg |
Expert insight: The Devine formula was originally designed for drug dosage calculations, not fitness goals. Yet it became the most commonly cited weight formula online. For general health screening, the Robinson or Miller formulas tend to give more realistic ranges for everyday adults.
Use a free online calculator to plug in your own height and instantly compare results across all these formulas.
Ideal Weight — Key Facts and Figures
The WHO classifies adult weight status using these BMI categories:
| BMI Range | Classification |
|---|---|
| Below 16.0 | Severe Underweight |
| 16.0 – 16.9 | Moderate Underweight |
| 17.0 – 18.4 | Mild Underweight |
| 18.5 – 24.9 | Normal Weight |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Obese Class I |
| 35.0 – 39.9 | Obese Class II |
| 40.0+ | Obese Class III |
According to WHO 2024 data, over 1.9 billion adults worldwide are overweight, and 650 million are classified as obese. Obesity rates have tripled since 1975 across every region.
⚠️ NOTE: BMI thresholds differ for Asian populations. The WHO Western Pacific Region recommends a healthy BMI cutoff of 23.0 (not 25.0) for overweight in East and South Asian adults, because health risks begin at lower BMI levels in these populations.
Age-related benchmarks also matter. The NIH acknowledges that adults over 65 may have slightly better health outcomes with a BMI of 25–27 compared to the standard "normal" range. Older adults with very low body weight face higher risks of fractures, muscle loss, and weakened immunity.
Key Factors to Consider
- Sex and Body Composition: Males typically carry more muscle mass, which weighs more than fat. Two people with identical BMIs can have vastly different body fat percentages. Women naturally carry 6–11% more body fat than men.
- Age: Metabolism drops roughly 1–2% per decade after age 20. Muscle mass decreases by about 3–8% per decade after age 30 (a process called sarcopenia). This means your healthy weight at 25 may differ from your healthy weight at 55.
- Frame Size: Wrist circumference is a quick proxy for bone structure. A small-framed 5'8" person may weigh 15 lbs less than a large-framed person of the same height and still be equally healthy.
- Waist Circumference: The WHO recommends tracking waist size as a separate risk indicator. Men above 40 inches (102 cm) and women above 35 inches (88 cm) face increased risk of heart disease and type 2 diabetes — regardless of BMI.
- Muscle Mass vs. Fat Mass: A muscular athlete at 5'10" and 210 lbs may have a BMI of 30.1 (classified as obese) but a body fat percentage of only 12%. BMI alone fails these individuals entirely.
- Ethnicity: Research published in The Lancet (2021) confirms that metabolic risk thresholds vary by ethnicity. South Asian adults show higher diabetes risk at lower BMIs compared to European adults.
Common Mistakes People Make
- Trusting a single number as gospel. No formula gives a universal "perfect weight." Your ideal range depends on body composition, health history, and fitness level. Correct approach: Use BMI as a starting point, then measure waist circumference and body fat percentage for a complete picture.
- Ignoring age-related changes. Many people compare themselves to their weight at age 20 and panic. Some weight gain with age is normal and even protective. Correct approach: Focus on maintaining muscle mass through resistance training rather than chasing a number from decades ago.
- Confusing BMI with body fat percentage. A BMI of 26 does not mean you are unhealthy. If your body fat percentage is within range and your bloodwork is normal, you may be perfectly fine. Correct approach: Ask your doctor for a body composition analysis, not just a BMI reading.
- Using children's charts for teens or vice versa. Pediatric weight assessment uses BMI-for-age percentile charts — completely different from adult BMI. A BMI of 22 means something very different for a 12-year-old than a 35-year-old. Correct approach: Use CDC growth charts for anyone under 20 and adult BMI tables for those 20 and older.
⚠️ WARNING: Crash dieting to reach an "ideal weight" number can cause muscle loss, metabolic damage, and nutrient deficiencies. The American Medical Association warns that rapid weight loss exceeding 2 lbs (1 kg) per week increases health risks significantly.
- Overlooking regional BMI differences. Applying Western BMI thresholds universally is a documented clinical mistake. Asian populations face elevated metabolic risks at lower BMI cutoffs. Correct approach: Use ethnicity-adjusted guidelines when available.
Practical Tips
Measure your waist-to-height ratio. This is a stronger predictor of cardiovascular risk than BMI alone. Keep your waist circumference below half your height. A 5'8" (68-inch) person should aim for a waist under 34 inches.
Track body composition, not just weight. A $30 body fat caliper or a smart scale with bioelectric impedance gives you far more useful data than a bathroom scale alone. Trends over weeks matter more than any single reading.
Adjust expectations by decade. A realistic target for a 50-year-old looks different than for a 25-year-old. Aim for the upper half of your healthy BMI range as you age, and prioritize strength and mobility over a number.
Recalculate after major life changes. Pregnancy, menopause, surgery, or prolonged illness all shift your baseline. Recalculate using an online calculator after any major physical change and set new, updated goals.
Prioritize protein intake. The NIH recommends 0.8 g of protein per kg of body weight as a minimum for adults. Active adults and those over 50 benefit from 1.0–1.2 g/kg to preserve muscle mass and maintain a healthy weight.
Consult a professional for personalized targets. If you earn $5,000 per month and can afford one specialist visit, a registered dietitian or sports medicine doctor can give you a body composition analysis and a personalized weight range that no online formula can match.
Your Next Step
Your healthy weight is a range, not a single number — and that range is unique to your body. Start by calculating your BMI and waist-to-height ratio using a trusted online calculator, then layer in body fat data and bloodwork for the full picture. Talk to a healthcare provider if your numbers fall outside the healthy range or if you are unsure how to interpret your results. Small, consistent steps toward strength and balanced nutrition will always serve you better than chasing a number on a scale.