ToolForage.
HEALTH CALCULATOR

BMI Calculator

Enter adult height and weight in metric or US units. Use total inches or feet and inches, and read BMI with the adult screening category.

Calculator

Valid height is carried between entries and unit systems.
kg
cm
ft
in
Use a whole number of feet and remaining inches below 12.
YOUR RESULTS
Body mass index22.9
Adult screening range
Healthy weight
BMI 18.5 weight
56.7 kg
BMI 24.9 weight
76.3 kg
Detailed adult screening range
Healthy weight
BMI divided by 25
0.9143

The adult screening category is healthy weight, based on the unrounded BMI. Rounded displays can reach a category boundary. BMI is not a diagnosis.

Page guide

Adult BMI ranges and their limits

BMI relates weight to height squared. The category is a population screening range for adults aged 20 and older; it does not measure body fat directly or diagnose health. Categories use the unrounded BMI, so a rounded display near a threshold can look like the next category. The detailed range distinguishes obesity classes at BMI 30, 35 and 40. BMI divided by 25 is a unitless arithmetic ratio to the upper screening boundary, not a separate health score.

For a separate estimate of resting energy and daily calorie needs, the Calorie Calculator uses age, height, weight, and activity level; it does not turn a BMI category into a calorie target.

The formula

BMI = weight (kg) ÷ height (m)²

For pounds and inches, values are converted with exact factors. The familiar US formula multiplies pounds divided by inches squared by approximately 703.

70 kg at 175 cm

Convert 175 cm to 1.75 m. BMI is 70 ÷ 1.75² = 22.86, within the CDC healthy-weight screening range for adults.

How to use this calculator

  1. Choose metric or US customary measurements. US height can use total inches or separate feet and inches.
  2. Enter height and weight. Valid height carries between entry modes; switching units converts the measurements.
  3. Read the live adult BMI, detailed screening range and mathematical weight endpoints.

Adult BMI screening ranges

CDC adult ranges are underweight below 18.5, healthy weight from 18.5 to below 25, overweight from 25 to below 30, and obesity at 30 or above.

These are screening categories. Health professionals interpret them with history and other measurements.

Obesity class 1 spans BMI 30 to below 35, class 2 spans 35 to below 40, and class 3 begins at 40. These subdivisions also use the unrounded value. The BMI divided by 25 output is 1 exactly at the BMI 25 boundary.

What BMI cannot show

BMI does not distinguish muscle from fat or show fat distribution.

Children and teens require age- and sex-specific percentiles; this calculator is for adults.

Assumptions & limitations

What this calculation assumes

  • The user is an adult aged 20 or older.
  • Height and weight are measured accurately.
  • Category labels use CDC adult thresholds.

What to keep in mind

  • BMI is a screening measure, not a diagnosis.
  • Pregnancy, muscularity, and some conditions can make BMI less informative.
  • The displayed weight span is mathematical, not an individualized target.

Common questions

Is a healthy-range BMI proof of good health?

No. BMI does not capture fitness, diet, blood pressure, lab results, or body composition.

Can children use this result?

No. Children and teens need BMI-for-age percentiles.

Why does switching units keep the same BMI?

The form converts the physical measurements before recalculating.

Sources & further reading

Reviewed on