Calculate your Body Mass Index to assess if you are at a healthy weight for your height.
Use the calculator to estimate a health or fitness number, then compare it with trends over time and other relevant context.
These tools are for education and planning. They do not replace medical advice.
BMI (Body Mass Index) is a measure of body fat based on height and weight. It is calculated by dividing weight in kilograms by height in meters squared (kg/m²). For US units, the formula is (weight in lbs / height in inches²) × 703.
A healthy BMI for adults is typically between 18.5 and 24.9. Below 18.5 is considered underweight, 25-29.9 is overweight, and 30 or above is obese. However, BMI does not account for muscle mass or body composition.
BMI has limitations. It does not distinguish between muscle and fat, so athletes or muscular individuals may have a high BMI despite low body fat. It also does not account for age, sex, or bone density. Use BMI as a general screening tool, not a diagnostic measure.
To reach a healthy BMI, focus on balanced nutrition and regular physical activity. Consult a healthcare provider or registered dietitian for personalized guidance based on your health status and goals.
Last updated: May 27, 2026 | Reviewed by Body Tally Team
Use the BMI calculator to estimate body mass index from height and weight. BMI is a broad screening number that can help adults compare weight relative to height, but it does not diagnose health, measure body fat directly, or account for muscle mass, pregnancy, age-related changes, or medical history.
Body Tally keeps the calculator near the top of the page and adds this guide so you can understand what the tool does, how the inputs affect the result, and what the result can and cannot tell you. Health and fitness formulas are useful for planning, but they work best when treated as estimates and compared with real trends, symptoms, training history, and professional guidance when appropriate.
BMI equals weight in kilograms divided by height in meters squared. In US units, weight in pounds is divided by height in inches squared and multiplied by 703.
The formulas use simplified inputs so they can be calculated quickly in a browser. They do not know your medical history, medications, hormones, lab results, training recovery, sleep, stress, or diagnosis. Use the answer as a starting point, then refine it with consistent measurements and qualified advice when the decision affects health.
Calculator results are useful for learning and planning, but they should not be the only basis for decisions when symptoms, medications, chronic conditions, pregnancy, eating disorder history, injury, or major changes in activity are involved.
If the estimate feels surprising, repeat the measurement, check your unit settings, compare one related calculator, and read the matching guide before acting on the number. Body Tally is built to help you ask better questions, not to replace qualified care.
No. BMI is a screening estimate and should not replace medical advice.
For many adults, 18.5 to 24.9 is commonly categorized as normal weight, but personal context matters.
BMI does not separate fat, muscle, bone, water, or body shape.