Calculator Tools

BMI Calculator

Calculate adult BMI from height and weight in metric or US units. Review the formula and CDC screening category for adults aged 20 and older, with private local processing.

Your content stays on your device Free, with no account

Height and weight. Adult screening only. Local calculation · no uploads

Screening scope

Measurement units

Weight (kg)

Height (cm)

Height · whole feet

Additional inchesEnter 0–less than 12 inches. Use zero when the height is an exact number of feet.

Changing measurement units clears the measurements so old numbers cannot be silently reinterpreted. Enter measurements or load the example to enable quick sliders.

Quick weight · kg (20–250)Drag to set weight to 0.1 kg/lb. The exact field supports positive values outside this quick range.

Quick height · cm (100–220)Drag to set height to 0.1 cm/in. Exact fields remain available when the quick slider is disabled.

BMI decimal places

Category uses the unrounded result, even if the displayed number rounds over a boundary.

For adults 20 and older, outside pregnancy. BMI is a screening measure, not a diagnosis or a direct body-fat measurement. Inputs stay on this device.

YOUR CALCULATION

BMI · kg/m²

Enter values to convert.

Adult screening reference

CDC categories for ages 20 and older. Highlighting uses the unrounded calculation.

Adult BMI categories · kg/m²
Category	BMI range
Underweight	Below 18.5
Healthy weight	18.5 to less than 25
Overweight	25 to less than 30
Obesity — class 1	30 to less than 35
Obesity — class 2	35 to less than 40
Obesity — class 3	40 or greater

CDC adult category reference ↗ · CDC child and teen calculator ↗

A FEW SIMPLE STEPS

How to use BMI Calculator

Check the screening scope: this tool uses CDC adult categories for ages 20 and older, outside pregnancy.
Choose metric or US measurements, then enter weight and height. A unit change clears measurements to avoid silently changing their meaning.
Use the quick sliders for convenient adjustment or type exact measurements. For US height, enter whole feet and additional inches from 0 to less than 12.
Review BMI, the adult screening category, formula and reference table. Choose display decimals, then copy or download a TXT report.

PRIVATE BY DESIGN

Why use this tool?

Height and weight are personal information. This calculator processes them entirely in your browser and never uploads or saves them. The formula and applied unit conversions are shown, with category comparisons made before display rounding.

Tool inputs stay in your browser. Only your theme preference is saved on this device.

A few things worth knowing

How is BMI calculated?

BMI equals weight in kilograms divided by height in metres squared. US inputs use exact conversions of 0.45359237 kg per pound and 0.0254 metres per inch. BMI is reported in kg/m².

Who are these categories for?

This page uses CDC screening categories for adults aged 20 and older. Children and teens need age-specific assessment, so adult categories are not applied here below age 20. Standard interpretation is also not used here during pregnancy.

Does BMI diagnose health or measure body fat?

No. BMI is a screening measure that needs context. It does not distinguish muscle from fat, measure fat distribution or account for all individual health factors. Discuss interpretation with a qualified health professional; this tool does not prescribe treatment or weight targets.

Why can a rounded BMI appear in the neighboring category?

Categories are compared using the unrounded calculation. For example, 24.96 can display as 25.0 to one decimal place while remaining below 25. Exact calculation details and additional display decimals are available.

Why do units clear the fields or sliders become disabled?

Changing units clears measurements rather than silently treating a kg value as lb. Quick sliders cover a convenient range; empty, invalid, out-of-range or unsuitable high-precision values disable them. Exact inputs remain available.

Are height and weight uploaded or stored?

No. All calculation happens locally and inputs are not persisted. Copy and TXT download happen only when you choose. Only the website theme preference is saved.

Adult screening reference

How to use BMI Calculator

Why use this tool?

A few things worth knowing

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