CalculateHealth & Fitness
BMI Calculator
Body Mass Index (BMI) is a simple screening tool that uses your height and weight to estimate whether your weight falls within a healthy range.
♢ Your data is private and not stored.
Your BMI
22.9
● Healthy weightYour BMI is within the healthy weight range for adults of your height.
Understand your result
BMI categories for adults (20+ years). Source: World Health Organization (WHO).
Underweight
BMI < 18.5May be associated with nutritional deficiency and other health risks.
Normal weight
BMI 18.5 – 24.9Associated with the lowest risk of many chronic diseases.
Overweight
BMI 25 – 29.9May increase risk for heart disease, diabetes and other conditions.
Obesity
BMI ≥ 30Higher risk of serious health conditions; support and treatment are available.
BMI is a screening tool, not a diagnosis. It does not measure body fat directly or account for muscle, bone, age, sex or ethnicity.
What BMI measures
BMI estimates body fat based on height and weight. It is used worldwide as a quick screening indicator of potential weight-related risk.
Key terms explained
WeightYour body mass.
HeightMeasured without shoes.
BMIWeight (kg) ÷ height (m)².
How to use this calculator
- Choose Metric or Imperial units.
- Enter your accurate weight.
- Enter your height.
- Review your BMI and category.
The formula
BMI is calculated using this formula:
÷ height (m)²
Worked example
Example: 70 kg, 175 cm
Height in metres: 1.75 m
BMI = 70 ÷ (1.75)² = 22.9
Result: Normal weight
What BMI cannot tell you
- Body fat percentage
- Muscle mass or strength
- Fat distribution
- Overall fitness or health status
When to speak with a professional
Speak with a doctor or dietitian if you:
- Have health conditions or take medication
- Are pregnant or planning pregnancy
- Have concerns about your weight or health
Frequently asked questions
- How accurate is BMI?
- Is BMI the same for men and women?
- Does BMI change with age?
- What is a healthy BMI goal?
Trusted sourcesWorld Health Organization (WHO)
Centers for Disease Control and Prevention
Reviewed byThis content is medically reviewed.
Last reviewed: July 28, 2026
Important noteThis calculator is for informational purposes only and does not replace professional medical advice.
Your privacy mattersYour values stay in your browser and are not sent to CalculateBetter.
Frequently asked questions
Clear answers to common questions about BMI, its uses and its limitations.
How accurate is BMI?+
BMI is a useful population-level screening measure because it relates weight to height, but it is not a direct measurement of body fat or health. Its accuracy for an individual can be affected by muscle mass, bone density, age, sex and ethnicity. Use it as a starting point alongside other health information.
Is BMI calculated differently for men and women?+
The adult BMI formula and standard category thresholds are the same for men and women. However, people with the same BMI can have different body-fat percentages and fat distribution, so sex and other individual factors still matter when a clinician interprets the result.
Does BMI change with age?+
The mathematical formula does not change for adults, but body composition often changes with age. Children and teenagers should not use adult category thresholds; their BMI is interpreted using age- and sex-specific growth percentiles.
What is considered a healthy BMI?+
For most adults, a BMI from 18.5 to 24.9 is classified as the healthy or normal-weight range. This range is a general screening guide rather than a personal target. Your appropriate weight range may depend on medical history, pregnancy, athletic build and advice from a healthcare professional.
Can BMI tell me my body-fat percentage?+
No. BMI uses only height and weight, so it cannot distinguish fat from muscle, bone or water. Skinfold measurements, bioelectrical impedance, DEXA scans and clinical assessment can provide more specific information about body composition.
Why can muscular people have a high BMI?+
Muscle is dense and contributes to body weight. An athlete or muscular person may therefore fall into an overweight BMI category despite having relatively low body fat. Waist measurement, body composition and overall metabolic health can add important context.
Should BMI be used during pregnancy?+
Standard adult BMI categories are not designed to assess weight changes during pregnancy. Pre-pregnancy BMI may help a clinician discuss recommended pregnancy weight gain, but current pregnancy weight should be interpreted with professional guidance.
When should I speak with a healthcare professional?+
Consider professional advice if your BMI is outside the healthy range, changes unexpectedly, or is accompanied by symptoms or concerns about eating, weight, growth or general health. A clinician can interpret BMI alongside your medical history, waist measurement, blood pressure and laboratory results.