BMI Calculator

Calculate your Body Mass Index instantly. Enter your weight and height to see your BMI, category, and healthy weight range for your height.

Optional: Add age and gender for additional context (BMI calculation remains the same)

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What is BMI?

BMI (Body Mass Index) is a simple measure that uses your height and weight to determine if your weight is healthy. It's calculated by dividing your weight in kilograms by your height in meters squared.

BMI is widely used as a screening tool by healthcare professionals to identify possible weight problems in adults. While it doesn't measure body fat directly, research has shown that BMI correlates with direct measures of body fat.

How is BMI Calculated?

The BMI formula is straightforward:

BMI Formula

Metric: BMI = weight (kg) / height (m)²

Imperial: BMI = (weight in lbs × 703) / height (inches)²

Example: A person weighing 70 kg who is 1.75 m tall: BMI = 70 / (1.75 × 1.75) = 22.9

BMI Categories

BMI values are divided into categories that help indicate whether your weight may pose health risks:

<18.5

Underweight

May indicate malnutrition or other health concerns

18.5-24.9

Normal Weight

Healthy weight range with lowest health risks

25-29.9

Overweight

Increased risk of health problems

30-34.9

Obese Class I

High risk of weight-related health conditions

35-39.9

Obese Class II

Very high risk of health complications

40+

Obese Class III

Extremely high risk, medical attention recommended

BMI Chart Reference

Use this chart to quickly reference BMI values for different height and weight combinations:

HeightBMI 18.5BMI 25BMI 30
5'0" (152 cm)94 lbs (43 kg)128 lbs (58 kg)153 lbs (69 kg)
5'4" (163 cm)108 lbs (49 kg)145 lbs (66 kg)174 lbs (79 kg)
5'8" (173 cm)122 lbs (55 kg)164 lbs (74 kg)197 lbs (89 kg)
6'0" (183 cm)136 lbs (62 kg)184 lbs (83 kg)221 lbs (100 kg)
6'4" (193 cm)152 lbs (69 kg)205 lbs (93 kg)246 lbs (112 kg)

* Values shown are approximate weights at each BMI threshold for the given height

Important Limitations of BMI

While BMI is a useful screening tool, it has several important limitations you should be aware of:

Doesn't Measure Body Fat

BMI cannot distinguish between muscle and fat mass. A muscular athlete may have a high BMI despite having low body fat.

Age Not Considered

Older adults may have more body fat than younger people at the same BMI. Standard BMI categories may not apply equally to all ages.

Gender Differences

Women naturally have more body fat than men. BMI does not account for these biological differences between sexes.

Ethnic Variations

Health risks associated with specific BMI values can vary by ethnicity. Some populations may have different optimal BMI ranges.

Important: BMI should be used as a general guide, not a definitive health measure. For a complete health assessment, consult with a healthcare provider who can consider additional factors like waist circumference, blood pressure, cholesterol levels, and family history.

When to Consult a Healthcare Provider

Consider speaking with a healthcare professional if:

  • Your BMI falls outside the normal range (below 18.5 or above 24.9)
  • You're experiencing unexplained weight changes
  • You have concerns about your weight and health
  • You want personalized advice on achieving a healthy weight
  • You have other health conditions that may affect weight

Frequently Asked Questions

What is BMI?

BMI (Body Mass Index) is a measure that uses your height and weight to calculate if your weight is healthy. It's calculated by dividing your weight in kilograms by your height in meters squared and is used as a screening tool to identify potential weight problems.

How is BMI calculated?

For metric units: BMI = weight (kg) / height (m)². For imperial units: BMI = (weight in lbs × 703) / height (inches)². Our calculator does this math automatically for you.

What are the BMI categories?

Underweight: below 18.5, Normal: 18.5-24.9, Overweight: 25-29.9, Obese Class I: 30-34.9, Obese Class II: 35-39.9, Obese Class III: 40 or higher. Each category indicates different levels of health risk.

Is BMI accurate for everyone?

BMI has limitations. It doesn't distinguish between muscle and fat, so muscular people may have a high BMI despite being healthy. It also doesn't account for age, gender, or ethnicity. Use BMI as one tool among many for health assessment.

What is a healthy BMI range?

A healthy BMI is generally considered to be between 18.5 and 24.9. This range is associated with the lowest health risks for most adults. However, optimal BMI can vary based on individual factors.

How often should I check my BMI?

For most adults, checking BMI once every few months is sufficient. If you're actively managing your weight, monthly checks can help track progress. Remember that BMI is just one health metric among many.

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