BMI (Body Mass Index) is a fast height/weight screening metric. It’s useful for trend tracking and broad category guidance, but it doesn’t measure body composition directly. Use this page for clear BMI math and practical interpretation.
BMI Calculator - Body Mass Index
Calculate your BMI and get personalized health recommendations
BMI Formula:
BMI = weight (kg) ÷ height² (m²) Or in imperial: weight (lbs) × 703 ÷ height² (inches²)
Your BMI
25.1
★ Rate this calculator:
Overweight
Healthy Weight Range:
125 - 169 lbs
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BMI Scale
▼ You
1518.5253040
Health Recommendation:
Consider increasing physical activity and focusing on portion control. Small, sustainable changes can make a significant difference.
Health disclaimer:BMI is a screening tool, not a diagnostic measure. Consult a qualified healthcare professional before making any health decisions based on this result.
BMI category ranges
Category
BMI Range
What it means
Underweight
Below 18.5
May indicate nutritional deficiency
Normal weight
18.5 – 24.9
Associated with lowest health risk
Overweight
25.0 – 29.9
Increased risk of some conditions
Obese Class I
30.0 – 34.9
High risk — consult a professional
Obese Class II
35.0 – 39.9
Very high risk
Obese Class III
40.0 and above
Extremely high risk
How BMI is calculated
According to standard WHO formulas, BMI is calculated by dividing weight in kilograms by height in meters squared. For imperial measurements, the formula uses a conversion factor of 703.
A BMI calculator is a health tool that estimates body mass index from height and weight to classify underweight, normal, overweight, or obesity in adults.
Where: symbols follow the inputs and conventions used in this calculator (principal, rates, terms, or units as labeled).
Real-World Example
Someone who is 5'10" and 180 lb has a BMI near 25.8.
Quick Reference
How to calculate Body Mass Index (BMI)?
Select units (metric or imperial) Enter your height Enter your weight Click calculate to see BMI and category Use results as a screening metric—not a diagnosis
Can you give a real-world Body Mass Index (BMI) example?
Someone who is 5'10" and 180 lb has a BMI near 25.8.
Is BMI accurate for athletes?
BMI can overestimate body fat for muscular people and underestimate it for older adults who have lost muscle. Pair BMI with waist size and professional advice when relevant.
📊 Did You Know?
As of 2024, 33% of US adults are obese (BMI ≥ 30) and 31.6% are overweight. Colorado has the lowest obesity rate at ~22%; West Virginia has the highest at ~41.4%. (CDC BRFSS, 2024)
How to Use This Calculator
Enter height and weight (choose units if available).
Read your BMI number and category.
Use BMI as a trend line over time, not a single-day judgment.
The Formula Explained
BMI = weight(kg) / height(m)^2
The formula scales weight by height squared, which makes BMI comparable across different heights. Because it uses only two inputs, it’s simple—but also limited.
Tips & What Your Results Mean
BMI is best used as a screening tool. If your BMI category changes over months, that’s a meaningful signal that your weight relative to height is trending. Day-to-day fluctuations are often water and glycogen.
If you lift weights or have high muscle mass, BMI can overestimate risk. In that case, consider tracking waist circumference or body fat percentage estimates. Your goal is health outcomes and performance, not a single number.
If BMI is rising and you want to reverse the trend, start with the basics: consistent steps, strength training, and improving diet quality. A moderate calorie deficit and high-protein meals often help preserve lean mass while losing fat.
If you have medical conditions or a history of disordered eating, BMI can be triggering or misleading. In that case, prioritize clinician guidance and broader health markers.
Frequently Asked Questions
What percent of US adults are obese?
As of 2024, about 33% of US adults are obese (BMI ≥ 30) and about 31.6% are overweight. (CDC BRFSS, 2024)
What is a healthy BMI range?
For many adults, 18.5–24.9 is considered the “normal” range. Under 18.5 is underweight, 25–29.9 is overweight, and 30+ is obese. These are screening categories, not diagnoses.
Is BMI accurate for athletes?
BMI does not distinguish muscle from fat. Very muscular people can have high BMI with low body fat. Use BMI as one signal and consider waist measurements, fitness, and clinical markers too.
Does BMI work for children?
Children and teens use age- and sex-specific BMI percentiles. This page is designed for adult BMI categories and general screening.
What states have the lowest and highest obesity rates?
Colorado is often cited as among the lowest (~22%), while West Virginia is among the highest (~41.4%). (CDC BRFSS, 2024)
Specialized Calculators
Explore demographic and use-case BMI variants with tailored context.
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