BMI Calculator
Calculate adult BMI from measured height and weight and show the CDC adult screening category. The result is general information, not a diagnosis.
Use the BMI Calculator
Calculate adult BMI from measured height and weight and show the CDC adult screening category. The result is general information, not a diagnosis.
Calculation, text generation and supported file processing happen locally in your browser; this batch does not require a new external processing service.
Health information only. This page performs the stated arithmetic/estimate and is not a diagnosis, treatment plan, medical clearance, fertility guarantee or substitute for a qualified health professional. Seek urgent medical care for urgent symptoms or concerning readings.
Reference used for this implementation: CDC adult BMI: https://www.cdc.gov/bmi/adult-calculator/bmi-categories.html
How to use it
Start with the realistic worked example, replace it with your own verified values or files, inspect the result, and check the stated assumptions and limitations before using the output.
How the BMI Calculator works
The BMI Calculator computes adult body mass index from weight and height and maps the number to the adult screening category displayed by the tool.
Calculation breakdown
ToolLott will explain the current inputs and displayed result here.
Adult BMI formula and screening categories
For adults, ToolLott divides weight in kilograms by height in metres squared. BMI is a screening measure and does not directly measure body fat or diagnose health conditions.
BMI = weight (kg) / height (m)^2The tool accepts adult ages 20 to 120 and uses the adult screening categories displayed on the page.
| Symbol / input | Meaning | Unit |
|---|---|---|
weight | Body weight | kg |
height | Height | m |
BMI | Body mass index | kg/m^2 |
Step-by-step method
- Confirm the age is in the adult input range used by the page.
- Square the entered height in metres.
- Divide weight in kilograms by height squared.
- Map the numeric BMI to the displayed adult screening category.
Worked example
An adult user enters age 35, weight 78 kg and height 1.75 m.
Example inputs
- Age = 35 years
- Weight = 78 kg
- Height = 1.75 m
Calculation / processing
Height squared = 1.75 x 1.75 = 3.0625 m^2BMI = 78 / 3.0625 = 25.469Displayed to one decimal place = 25.5 kg/m^2
BMI is one screening indicator. It does not distinguish muscle from fat, show fat distribution or replace an individual clinical assessment.
Assumptions
- The page uses the adult BMI formula for people aged 20 and older.
- Height and weight measurements entered by the user are assumed accurate.
- The category is a screening classification, not an individual diagnosis.
Limitations
- BMI does not directly measure body fat or body composition.
- Individual health interpretation can depend on medical history, physical examination, laboratory findings and other measures.
- Children and teenagers require age- and sex-specific growth references rather than the adult categories used here.
Common questions
Is BMI a diagnosis?
No. CDC describes BMI as a screening measure that should be considered with other health information.
Why does BMI use height squared?
That is the standard adult BMI definition: weight in kilograms divided by the square of height in metres.
Should children use this calculator?
No. Children and teenagers use age- and sex-specific BMI-for-age references rather than the adult category thresholds on this page.
Methodology sources
Related ToolLott tools
A realistic way Priya could use this tool
Priya is a person tracking general wellness information.
Priya records a measured height of 1.75 m and weight of 78 kg and wants the adult BMI arithmetic written down consistently for a personal tracking note.
Priya enters age 35, 78 kg and 1.75 m. The calculator applies BMI = weight / height², so 78 / 1.75² = 25.47 kg/m², then maps that number to the displayed CDC adult screening category.
The result is BMI 25.5 kg/m², displayed in the adult overweight screening category. Priya has a reproducible calculation for her note, while the tool explicitly avoids presenting BMI as a diagnosis or individual health assessment.
Fictional scenario using realistic example data. For Ready tools, the worked result is tied to the tested example shown in the tool. Replace the figures with your own inputs and independently verify important professional, financial, legal, health or safety decisions.
What this calculator is for
Use it to calculate adult BMI from measured height and weight and show the CDC adult screening category. The result is general information, not a diagnosis.
It sits within ToolLott’s Health Calculators collection, where you can also calculate BMI, BMR, body fat, calorie needs, heart-rate zones, ovulation dates and pregnancy dates for general information.