Know your numbers.
See your progress.
Calculate your body mass index, understand the result, and follow your measurements over time.
Your measurements
Your live BMI meter
The needle moves as you type. Enter valid weight, height and age to begin.
Only saved readings appear in your progress graph.
Small check-ins. A bigger picture.
Your progress over time
See the pattern behind your readings.
Your journey will take shape here.
Calculate and save a reading to start your graph.
Only readings you choose to save will appear here.
Your reading history
One saved reading per date. Edit whenever you need.
Keep a goal in view.
A weight goal is optional. Choose a suitable target with your healthcare professional.
Your data stays with you.
Readings stay in this browser on this device. Clearing browser data can remove them.
One person's history per browser profile. Use a backup to move it to another device. No account sync or server upload.
A little context helps.
How is BMI calculated?
BMI = weight in kilograms ÷ height in metres squared. Imperial inputs are converted using 1 lb = 0.45359237 kg and 1 inch = 2.54 cm. The result is rounded for display; adult categories use the unrounded value.
Standard adult categories: underweight below 18.5; healthy weight 18.5 to <25; overweight 25 to <30; obesity class 1: 30 to <35; class 2: 35 to <40; class 3: 40 or above.
Who can use this calculator?
Numerical BMI is available from ages 2–120. Standard adult categories and the reference weight range are shown only from age 20 and outside pregnancy. Ages 2–19 need sex-specific BMI-for-age growth charts; this tool does not calculate percentiles or classify a child's weight.
During pregnancy, speak to your maternity care team about weight monitoring. Personal weight goals are disabled for children, teens, and pregnancy readings.
What can BMI tell me?
BMI is a screening measure, not a diagnosis or a body-fat test. It does not distinguish fat from muscle, bone, or fluid. Muscle mass, older age, medical conditions, and ethnic background can affect interpretation.
Some backgrounds, including South Asian, can have cardiometabolic risk at a lower BMI. A clinician can assess this alongside waist measurements and other health factors.
How are the graphs and saves handled?
One reading is saved per local calendar date. Weekly averages use Monday–Sunday weeks; monthly and yearly averages use calendar periods. Each average includes only saved readings, not unmeasured days. The 12-month view includes this month and the previous 11 months.
Graphs connect saved measurements; they do not estimate values for missing days. Download a JSON backup to restore your readings. CSV is for spreadsheets. Print / PDF uses your browser's print dialog.