Quick start
- Open the BMI Calculator.
- Enter height in centimeters (cm) and weight in kilograms (kg). This calculator uses metric inputs only.
- Use the first example, "Healthy range example: 170 cm, 70 kg", if you want to see a filled-out calculation before entering your own values.
- Calculate, read the formula line, then copy the result only after the units and assumptions look right.
Best uses
Start here if one of these sounds like your job. The examples below show which inputs matter most.
- Estimate adult BMI from metric height and weight.
- Compare BMI with common adult screening categories.
- Find the weight range that matches BMI 18.5 to 24.9 for a height.
- Use a consistent estimate while tracking health or fitness changes.
What this calculator is for
The BMI Calculator turns height and weight into one adult screening number. It is useful for a quick reference, but it does not see muscle, pregnancy, age-related body composition, or a clinician view of health.
Use it when you want to: Estimate adult BMI from metric height and weight. Compare BMI with common adult screening categories.
What to enter
Check that height is in centimeters and weight is in kilograms before calculating. This page has no feet, inches, or pounds input mode.
- Enter height in centimeters (cm) and weight in kilograms (kg). This calculator uses metric inputs only.
- For feet and inches, multiply feet by 12 and add the remaining inches. Multiply that total by 2.54 for centimeters. Multiply pounds by 0.45359237 for kilograms.
- Use a recent weight if you are checking today, or use the same measurement conditions if you are tracking a trend.
- Use this adult tool for adults, not for child or teen BMI percentiles.
Example walkthrough
Try the calculator example: Healthy range example: 170 cm, 70 kg. The example result is BMI about 24.2.
- For 170 cm and 70 kg, the calculator converts height to meters, squares it, then divides 70 by that squared height.
- The result is about 24.2, which sits inside the common adult healthy-weight BMI category.
Formula and steps
In plain language: BMI is calculated as weight in kilograms divided by height in meters squared, then compared with adult BMI screening categories. Read the result together with the notes on the page, because health and fitness numbers often need personal context.
Read the formula note when you need to understand where the number came from, especially before comparing results over time.
How to read the answer
Read the main estimate first, then read the note beside it. For health, pregnancy, nutrition, kidney, alcohol, or training decisions with real consequences, use qualified professional guidance.
- Start with the BMI number, then read the category label as a broad screen rather than a final health score.
- The healthy weight range shows what weights would land between BMI 18.5 and 24.9 for the same height.
Common mistakes to avoid
Most bad results come from a small input mistake or from using a rough estimate for a decision it cannot safely answer.
- Do not use BMI alone to judge fitness, body fat, or medical risk.
- Do not enter feet or inches in the centimeter field, or pounds in the kilogram field. Convert those measurements first.
- Do not use adult BMI categories for children, teens, or pregnancy weight questions.
What to try next
A related health tool can help check the same topic from another angle, but one number should not replace proper care.
- Use Healthy Weight Calculator for the height-based range.
- Use Body Fat Calculator if you want a tape-measure estimate alongside BMI.
Sources and safety notes
This guide uses public-health, clinical, or peer-reviewed references where the calculator needs a specific formula or interpretation boundary.
Source links are provided for transparency, but they do not turn the calculator into medical advice or a replacement for professional care.
Worked examples for BMI Calculator
BMI about 24.2
BMI about 24.5
BMI about 20.3
FAQ in plain language
When should I use the BMI Calculator?
Use it for simple educational checks, trend tracking, or planning tasks like these: Estimate adult BMI from metric height and weight. Compare BMI with common adult screening categories. It can help you understand a number, but it cannot explain your whole health situation.
What do the main BMI Calculator inputs mean?
Enter adult height in centimeters (cm) and weight in kilograms (kg). For feet and inches, multiply feet by 12 and add the remaining inches. Multiply that total by 2.54 for centimeters. Multiply pounds by 0.45359237 for kilograms. This page is for adult BMI screening only. Children and teens use age-and-sex percentiles instead.
What is the BMI Calculator doing with my inputs?
In plain language: BMI is calculated as weight in kilograms divided by height in meters squared, then compared with adult BMI screening categories. Read the result together with the notes on the page, because health and fitness numbers often need personal context.
How should I read the BMI Calculator result?
Read BMI as a quick adult screening number. It can miss important context such as pregnancy, high muscle mass, waist size, body composition, age, medical history, and ethnicity. Use it as a clue, not a final health answer.
Can children, teens, pregnant people, or athletes use adult BMI the same way?
No. Children and teens need BMI percentiles, pregnancy changes body weight for a different reason, and athletes can have more muscle mass than BMI expects. In those cases, use BMI only as a rough note and ask a qualified professional for real guidance.
Can I use this as medical advice?
No. BMI is an educational adult screening estimate, not medical advice and not a diagnosis. Talk with a qualified health professional before making medical, pregnancy, nutrition, medication, or safety decisions. Use the calculator as a learning tool, then ask a qualified professional about decisions that affect care, pregnancy, medication, nutrition, or safety.
What should I double-check before trusting the result?
Check the units, date, and personal details before reading the answer. For example, pounds and kilograms, inches and centimeters, or a wrong activity level can change the result quickly. If the number feels surprising, rerun it slowly and compare it with the examples.
Related tools
- Healthy Weight CalculatorFind the adult BMI 18.5 to 24.9 weight range for a height.
- Body Fat CalculatorEstimate body fat percentage with a Navy-style tape method.
- Ideal Weight CalculatorEstimate Devine ideal body weight and compare it with the adult healthy BMI range.
Keep exploring
If this guide is close but not exact, these links keep you near the same kind of problem.
- Health & FitnessBrowse the full category for related tools that help with the same job.
- All free toolsSearch the complete Access Free Tools library by task, category, or tool name.
- All calculator and utility guidesFind more plain-language examples, formulas, mistakes, and result explanations.
- Free calculator resourcesStart here when you are not sure which calculator page fits.
Privacy and copying results
Recent answers stay visible only while you work in the current browser tab. They are not sent to a server.
Use Copy answer when you want to save the inputs and result in notes, homework, a message, or a project list. Check the units, labels, and limits before copying.