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HEALTH CALCULATOR

BMI Calculator

Calculate body mass index for an adult using metric or US customary measurements. See the CDC adult screening range and a weight span corresponding to BMI 18.5–24.9.

Calculator

kg
cm
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

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

Understanding your result

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.

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 units.
  2. Enter adult weight and height.
  3. Calculate and interpret the value with the limitations below.

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.

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