Child BMI Calculator
Computes body mass index as weight in kilograms divided by height in metres squared, shown to one decimal. It reports the BMI number only and reminds you to compare it against a CDC age-and-sex percentile chart.
What this calculator does
The Child BMI Calculator estimates your result instantly from the values you enter, using standard health & fitness formulas. Computes body mass index as weight in kilograms divided by height in metres squared, shown to one decimal. It reports the BMI number only and reminds you to compare it against a CDC age-and-sex percentile chart. Calculations run in your browser, so nothing you type is sent to a server, and the output is an estimate rather than a certified or official figure.
Result
About Child BMI Calculator
The Child BMI Calculator computes body mass index using the standard formula: weight in kilograms divided by the square of height in metres (height in cm is converted for you). It returns the BMI value to one decimal place. Note that this tool outputs the raw BMI number and does not itself classify it; for children, BMI is interpreted against a CDC age-and-sex percentile chart.
Formula & Mathematical Calculation
BMI = f(Weight (kg), Height (cm))
Calculated according to standard health formulas implemented in the calculator core.
Calculation Example
For a weight of 30 kg and height of 130 cm (1.30 m): BMI = 30 / (1.30 x 1.30) = 30 / 1.69, which the tool shows as BMI = 17.8, with the note: "BMI is 17.8. For children, compare against a CDC age-and-sex percentile chart."
Key Benefits
- Calculates BMI with the standard weight-over-height-squared formula
- Converts height from centimetres to metres automatically
- Reminds you that a child's BMI should be read against a CDC percentile chart rather than adult cut-offs
How to Use this Calculator
-
Enter weight
Type the weight in kilograms into the Weight (kg) field (for example 30). -
Enter height
Type the height in centimetres into the Height (cm) field (for example 130). -
Calculate
Click Calculate and read the BMI result box and the note below it.
Assumptions & Limitations
What the calculation assumes
- Every value you enter is treated as an exact, known amount.
- Any rate or interval you enter is assumed to hold for the whole period unless the form asks for it separately.
- Results use standard published formulas and account only for the values entered above.
- Rounding is applied for display; the underlying calculation uses your full precision.
- Results are returned in the same units you enter, unless the tool states the output unit.
What it does not cover
- Child BMI Calculator produces a calculated result for reference and learning, not a certified or official measurement.
- Real-world outcomes differ when tolerances, rounding rules or local standards apply.
- Definitions and standards vary by region and change over time; verify the convention that applies to your case.
- Figures are only as accurate as the inputs you supply — check them before acting on the result.
- For work where the result carries real consequences, confirm it against an authoritative source.
Frequently Asked Questions
Free to use, no account needed. Calculations run in your browser, so nothing you type is sent to a server. Results are estimates — how we build and check our calculators.