Understand the BMI categories for adults, why the cutoffs don't change with age, and the healthy weight range by height in pounds — plus how BMI works for children and teens. ✓ CDC & WHO
For adults, the WHO/CDC BMI cutoffs are the same for everyone aged 20 and over — they do not change with age or differ by gender. BMI = weight (kg) ÷ height (m)².
| Category | BMI range | What it means |
|---|---|---|
| Underweight | Below 18.5 | May indicate under-nutrition; worth discussing with a clinician. |
| Healthy weight | 18.5 – 24.9 | Associated with the lowest weight-related health risk for most adults. |
| Overweight | 25.0 – 29.9 | Raised risk of some conditions; other factors matter too. |
| Obesity — Class 1 | 30.0 – 34.9 | Higher risk of type 2 diabetes, heart disease and more. |
| Obesity — Class 2 | 35.0 – 39.9 | Substantially higher health risk. |
| Obesity — Class 3 | 40.0 and above | Sometimes called severe obesity; highest weight-related risk. |
💡 BMI cutoffs don't change with age for adults — but the healthy weight in pounds does change with your height. The table below shows the healthy weight range (BMI 18.5–24.9) for each height.
Because BMI depends on height, the healthy weight range in pounds varies by height even though the BMI cutoffs are identical for all adults. Same for men and women at a given height.
| Height | Height (cm) | Healthy weight (lbs) | Healthy weight (kg) |
|---|---|---|---|
| 4'10" | 147 cm | 89 – 119 lbs | 40 – 54 kg |
| 4'11" | 150 cm | 92 – 123 lbs | 42 – 56 kg |
| 5'0" | 152 cm | 95 – 127 lbs | 43 – 58 kg |
| 5'1" | 155 cm | 98 – 132 lbs | 44 – 60 kg |
| 5'2" | 157 cm | 101 – 136 lbs | 46 – 62 kg |
| 5'3" | 160 cm | 104 – 141 lbs | 47 – 64 kg |
| 5'4" | 163 cm | 108 – 145 lbs | 49 – 66 kg |
| 5'5" | 165 cm | 111 – 150 lbs | 50 – 68 kg |
| 5'6" | 168 cm | 115 – 154 lbs | 52 – 70 kg |
| 5'7" | 170 cm | 118 – 159 lbs | 54 – 72 kg |
| 5'8" | 173 cm | 122 – 164 lbs | 55 – 74 kg |
| 5'9" | 175 cm | 125 – 169 lbs | 57 – 76 kg |
| 5'10" | 178 cm | 129 – 174 lbs | 58 – 79 kg |
| 5'11" | 180 cm | 133 – 179 lbs | 60 – 81 kg |
| 6'0" | 183 cm | 136 – 184 lbs | 62 – 83 kg |
| 6'1" | 185 cm | 140 – 189 lbs | 64 – 86 kg |
| 6'2" | 188 cm | 144 – 194 lbs | 65 – 88 kg |
| 6'3" | 191 cm | 148 – 199 lbs | 67 – 90 kg |
| 6'4" | 193 cm | 152 – 205 lbs | 69 – 93 kg |
| 6'5" | 196 cm | 156 – 210 lbs | 71 – 95 kg |
| 6'6" | 198 cm | 160 – 215 lbs | 73 – 98 kg |
| 6'7" | 201 cm | 164 – 221 lbs | 74 – 100 kg |
| 6'8" | 203 cm | 168 – 227 lbs | 76 – 103 kg |
Values are rounded. Ranges are identical for men and women of the same height because BMI uses only height and weight.
For anyone under 20, BMI is not compared to fixed adult cutoffs. Instead, the CDC uses BMI-for-age growth charts that account for age and sex, because healthy body fat changes as children grow and differs between boys and girls.
| Category | BMI-for-age percentile |
|---|---|
| Underweight | Less than the 5th percentile |
| Healthy weight | 5th to less than the 85th percentile |
| Overweight | 85th to less than the 95th percentile |
| Obesity | 95th percentile or greater |
A child's percentile depends on their exact age (in months) and sex, so it can't be read from a single static table. Use the official CDC tool for an accurate percentile: CDC BMI Percentile Calculator for Child & Teen ↗. We link out rather than reproducing the CDC's copyrighted growth charts.
For adults (20 and older), the BMI category cutoffs are fixed and do not change with age: underweight is below 18.5, a healthy weight is 18.5–24.9, overweight is 25–29.9, and obesity is 30 or above. These thresholds come from the World Health Organization and are used by the CDC. What does change with height is the number of pounds that fall inside the healthy range — which is why the height table above is the more practical reference for most people.
For children and teens (2–19), age is built directly into the assessment. The CDC compares a child's BMI to other children of the same age and sex and reports a percentile, because the amount of body fat considered healthy shifts a lot during growth. That's the key difference: adults are measured against fixed numbers, kids against age-and-sex percentiles.
BMI is a useful population-level screen, but it has real limitations for individuals — and especially for older adults. It doesn't distinguish muscle from fat or capture where fat is stored. With age, people tend to lose muscle and gain fat even if weight is stable, so BMI can understate body fat in seniors. Some research suggests a slightly higher BMI (into the mid-20s) may be acceptable or even protective in older age. BMI also doesn't account for athletes with high muscle mass (who may read as "overweight") or differences across ethnic groups. Treat BMI as one signal alongside waist circumference, body composition and a clinician's advice.