What is my BMI?
Enter your height and weight to see your BMI and its adult category. Or enter a BMI to find the weight or height that gives it.
- Your BMI
- 23
At 160 lb, your BMI is 23, which is in the Healthy weight range for adults.
Healthy weight
- Underweight
- Healthy weight
- Overweight
- Obesity
- Category
- Healthy weight
- Healthy weight from
- 128.6 lb
- Healthy weight up to
- 173.9 lb
Your BMI: 23. At 160 lb, your BMI is 23, which is in the Healthy weight range for adults.
Where does my BMI fall?
Your BMI by weight
This calculator gives general information only. It is not medical advice and does not replace a doctor or other health care provider. Talk with a professional about your results. Terms of use
How to calculate
Computes body mass index (weight in kilograms divided by height in metres squared) and its CDC adult category, or the weight or height that gives a chosen BMI.
Example with the default inputs (Height 5 ft 10 in, Weight 160 lb): At 160 lb, your BMI is 23, which is in the Healthy weight range for adults.
Formula: BMI = weight ÷ height², with weight in kilograms and height in metres (CDC).
- The categories are the CDC adult categories, for people aged 20 and older. Children and teens use BMI-for-age percentiles instead.
- BMI is a screening measure. It does not measure body fat directly and does not diagnose health.
- The category is read from the BMI rounded to one decimal place, as shown: 18.5 to 24.9 is healthy weight, so 24.96 (rounded to 25.0, shown as 25) is overweight.
- The healthy weight range is the weights whose BMI shows as 18.5 to 24.9 at your height: BMI 18.45 to just under 24.95.
Worked examples
Each example is checked against the calculator on every build.
- Weight 150 lb, Height 5 ft 5 in gives BMI 24.96, Category Overweight.Source: CDC English formula: 150 lb ÷ (65 in)² × 703 = 24.96 (weight and height given here in kg and m: 1 lb = 0.45359237 kg, 1 in = 0.0254 m); rounded to 25.0, overweight in the NHLBI one-decimal table (25.0 to 29.9)
- Weight 154.3 lb, Height 5 ft 8.9 in gives BMI 22.857143, Healthy weight from 124.6 lb, Healthy weight up to 168.5 lb.Source: hand calculation in content.mdx: 70 ÷ 1.75² = 22.86; 18.45 × 1.75² = 56.50 kg; 24.95 × 1.75² = 76.41 kg
- BMI 18.5, Height 5 ft 9 in gives Weight 125.3 lb.Source: CDC adult BMI categories: at 5 ft 9 in, 125 lb is the start of the healthy range; 18.5 × 1.7526² = 56.82 kg = 125.3 lb (hand calculation in content.mdx)
- Weight 198.4 lb, BMI 30 gives Height 5 ft 8.2 in, Category Obesity.Source: hand calculation in content.mdx: height = √(90 ÷ 30) = √3 = 1.732 m; BMI 30 is obesity (CDC)
How BMI is worked out
BMI = weight ÷ height²
- weight is in kilograms and height is in metres. The calculator converts pounds, feet and inches for you (1 lb = 0.45359237 kg and 1 in = 0.0254 m, exactly).
- In pounds and inches the same formula is weight ÷ height² × 703. The 703 comes from the unit conversion (it is 703.07 to two decimals), so the two versions can differ in the second decimal place.
Fill in any two of height, weight and BMI, and the calculator finds the third:
- weight = BMI × height²
- height = √(weight ÷ BMI)
The calculator shows BMI to one decimal place, with halves rounded up (24.95 rounds to 25.0). A trailing .0 is left off, so 25.0 shows as 25.
Adult categories (CDC, age 20 and older)
| BMI | Category |
|---|---|
| Less than 18.5 | Underweight |
| 18.5 to less than 25 | Healthy weight |
| 25 to less than 30 | Overweight |
| 30 or greater | Obesity |
The category comes from the BMI as shown, rounded to one decimal place. This is how the NHLBI table lists the same categories (healthy 18.5 to 24.9, overweight 25.0 to 29.9), and it means the number and its category never disagree. On the unrounded BMI the edges are:
| Unrounded BMI | Shows as | Category |
|---|---|---|
| Less than 18.45 | 18.4 or less | Underweight |
| 18.45 to less than 24.95 | 18.5 to 24.9 | Healthy weight |
| 24.95 to less than 29.95 | 25.0 to 29.9 | Overweight |
| 29.95 or greater | 30.0 or more | Obesity |
The healthy weight range for your height is the weights whose BMI shows as 18.5 to 24.9: from 18.45 × height² up to (just under) 24.95 × height².
Obesity is sometimes split further: class 1 is 30 to less than 35, class 2 is 35 to less than 40, and class 3 is 40 or greater.
Assumptions
- The categories are for adults aged 20 and older. Children and teens use BMI-for-age percentiles.
- BMI is a screening measure, not a diagnosis. It does not measure body fat directly.
Worked examples by hand
150 lb at 5 ft 5 in. In pounds and inches: 150 ÷ 65² × 703 = 150 ÷ 4,225 × 703 = 24.96. In metric units: 150 lb = 68.039 kg and 65 in = 1.651 m, so 68.039 ÷ 1.651² = 24.961. To one decimal that is 25.0 (shown as 25), so the category is overweight. The healthy range at 5 ft 5 in ends just under 24.95 × 1.651² = 68.01 kg (149.93 lb, shown as 149.9 lb). The range ends are shown to 0.1 lb, so a weight within 0.05 lb of an end can fall on either side of it.
70 kg at 1.75 m. 70 ÷ 1.75² = 70 ÷ 3.0625 = 22.86, shown as 22.9, a healthy weight. The healthy range at 1.75 m is 18.45 × 3.0625 = 56.50 kg up to (just under) 24.95 × 3.0625 = 76.41 kg.
The weight that gives BMI 18.5 at 5 ft 9 in. 69 in = 1.7526 m. weight = 18.5 × 1.7526² = 18.5 × 3.07161 = 56.82 kg, which is 125.3 lb. The CDC chart for 5 ft 9 in starts the healthy range at 125 lb.
The height at which 90 kg is BMI 30. height = √(90 ÷ 30) = √3 = 1.732 m. A BMI of 30 is in the obesity range.
Other questions people ask
How is BMI calculated?
BMI is your weight in kilograms divided by your height in metres squared. In pounds and inches, it is weight ÷ height² × 703. For example, 150 lb at 5 ft 5 in (65 in) is 150 ÷ 65² × 703 = 24.96, which rounds to 25.0 (the calculator shows 25).
What do the BMI categories mean?
For adults 20 and older, the CDC uses these categories. Underweight is a BMI under 18.5. Healthy weight is 18.5 to less than 25. Overweight is 25 to less than 30. Obesity is 30 or more, split into class 1 (30 to less than 35), class 2 (35 to less than 40) and class 3 (40 or more). The calculator reads the category from the BMI rounded to one decimal place, as the NHLBI table does (18.5 to 24.9 is healthy weight), so the number you see and its category always agree.
What is a healthy weight for my height?
The weights that give a BMI of 18.5 to 24.9 (rounded to one decimal) at your height: 18.45 × height² up to just under 24.95 × height², with height in metres and weight in kilograms. At 5 ft 9 in, that is about 125 to 168 pounds, as on the CDC chart.
Can I use this calculator for children or teens?
No. For people under 20, the CDC compares BMI with others of the same age and sex using BMI-for-age percentiles. The adult categories here do not apply.
Does BMI measure body fat?
Not directly. BMI is a quick screening measure based only on height and weight. Two people with the same BMI can have different amounts of body fat, for example an athlete with a lot of muscle. A health care provider can do further checks.