Health & Fitness Calculators
BMI Calculator
Check BMI using height and weight in US or metric units.
US units are selected by default. Switch to metric if needed.
Enter your weight in pounds.
Enter feet only.
Enter the remaining inches.
Calculation assumptions
- *BMI is a screening estimate based on height and weight only.
- *It does not directly measure body fat, muscle mass, or fat distribution.
- *Adult BMI categories may not apply well to children, pregnancy, athletes, older adults, or unusual body composition.
- *Use BMI as context, not as a diagnosis or medical recommendation.
Enter your values and press Calculate.
Results and breakdowns will appear here after a valid calculation.
What is BMI?
Body Mass Index (BMI) is a screening estimate based on height and weight. It is often used as a quick population-level reference, but it is not a diagnosis.
Formula: BMI = weight in kilograms / height in meters squared. Example: 70 kg at 1.75 m gives 70 / (1.75 x 1.75) = 22.9.
BMI Categories Explained
- Underweight:Below 18.5
- Normal weight:18.5 - 24.9
- Overweight:25.0 - 29.9
- Obese:30.0 or higher
Limitations of BMI
BMI has important limits. Athletes with high muscle mass may have a high BMI without high body fat, while older adults may have a normal BMI with lower muscle mass. BMI also does not account for pregnancy, children, ethnicity, body frame, or fat distribution.
Common mistakes
- Treating BMI as a diagnosis instead of a screening estimate.
- Using adult BMI categories for children or pregnancy.
- Ignoring body composition, muscle mass, and health context.
- Comparing results without checking that the same units were used.
Quick answers
What this calculator answers
- Result: Calculates BMI and places it in a broad adult BMI category.
- Method: Uses BMI = weight in kilograms divided by height in meters squared.
- Use cases: Useful as a quick adult screening estimate or starting point for a health conversation.
- Limit: BMI is not a diagnosis and does not measure muscle, body fat, pregnancy, age, or individual health status.
- Related guide: Read the BMI guide for what the number can and cannot tell you. what BMI can and cannot tell you
Transparency note
Accuracy and limitations
Calzivo tools are built for practical estimates, conversions, and checks. Some tools use standard formulas or simplified assumptions, and results can be affected by input accuracy, rounding, units, local rules, or changing official requirements.
Health and fitness results are estimates, not medical advice. Formulas simplify real bodies and cycles, so important health decisions should be checked with a qualified clinician.
Reference check
Sources and references
These references provide background context for the topic. They do not replace official advice or documents for personal decisions.
- Adult BMI Calculator
Centers for Disease Control and Prevention
How to Use This Tool
Use these steps to enter the right inputs and interpret the result correctly.
Choose US or Metric units.
Enter your weight and height in the matching unit system.
Press Calculate to see your BMI score and category.
Refer to the gauge chart to see where you fall on the scale.
Consult with a healthcare provider for a full health assessment.
Related Tools
Other helpful tools in the Health & Fitness Calculators category.
Body Fat Calculator
Estimate body fat percentage from body measurements or a rough BMI-based method with general category guidance.
Ideal Weight Calculator
Estimate ideal weight range from height and the Devine formula.
Calorie Calculator
Estimate how many calories you need daily.
BMR Calculator
Calculate your Basal Metabolic Rate.
Macro Calculator
Calculate your ideal macronutrient breakdown.
Lean Body Mass
Estimate your lean body mass and body composition.
Related Guides
Background reading and explanations related to BMI Calculator.
BMI Explained (What It Means and When It Misleads You)
What your BMI score really means.
BMI Limits: What BMI Can and Cannot Tell You
Understand BMI as a screening estimate and where body composition context matters.
Ideal Weight Is an Estimate, Not a Diagnosis
Read ideal-weight formula results as rough context, not medical conclusions.
Frequently Asked Questions
Common questions about BMI Calculator and how to read the result.
Is BMI accurate for everyone?
BMI is a general screening estimate for most adults. It can mislead for children, pregnancy, athletes, older adults, or people with unusual body composition.
What is a healthy BMI?
For many adults, 18.5 to 24.9 is commonly labeled normal weight, but health context matters and BMI alone is not a diagnosis.
Can BMI diagnose a health condition?
No. BMI does not diagnose, treat, or manage medical conditions.
Should I worry if my BMI is high?
A high BMI can be a reason to look at broader health context, but a clinician can interpret it alongside other measurements and history.
Does BMI measure body fat?
No. BMI uses only height and weight, so it does not directly measure body fat or muscle mass.
Which units can I use?
You can use US units with pounds, feet, and inches or metric units with kilograms and centimeters.