Free Fitness Calculator
Know your numbers.
Use them wisely.
Estimate your adult BMI and resting calorie needs in seconds. No account, payment, or data submission is required.
Free to use
Adults 20+
Calculated in your browser
BMIWeight relative to height
BMRResting estimate; activity not included
Estimates are educational screening information, not medical advice or prescribed calorie targets.
Enter your information
Calculate your BMI and estimated BMR.
Your entries stay on this device and are used only to display the results below.
Your estimates
Your BMI
<18.518.5–24.925–29.930+
These numbers are estimates. Activity level is not included, so the resting-energy result is not a daily maintenance estimate or recommended calorie intake. BMI is a screening measure, and neither result substitutes for individual medical or nutrition guidance.
Understanding BMI
A screening number, not a complete health assessment.
Body mass index compares weight with height. It does not directly measure body fat, muscle, bone density, fat distribution, fitness, laboratory values, health behaviors, or medical history. Athletes and people with higher muscle mass may receive a result that does not reflect their body composition.
BMI = kg ÷ m²
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Understanding BMR
An estimate of energy used while your body is at rest.
“At rest” means the energy your body uses for essential functions such as breathing, circulation, brain and organ activity, temperature regulation, and cellular maintenance.
Activity level is not included. The estimate does not account for walking, work, household activity, exercise, or digestion.
This calculator uses the Mifflin–St Jeor predictive equation for resting energy expenditure. Your actual resting energy use can differ because of body composition, genetics, health, medications, environment, measurement conditions, and other individual factors.
9.99W + 6.25H − 4.92A + S
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Adult BMI categories
How the calculated result is categorized.
The calculator uses CDC adult categories for people age 20 and older. Categories are not adjusted for age, sex, or race and should be considered with other information.
Underweight< 18.5
Healthy weight18.5–24.9
Overweight25.0–29.9
Obesity, Class 130.0–34.9
Obesity, Class 235.0–39.9
Obesity, Class 340.0+
Numbers are only a starting point
Choose the support that fits your next step.
Use the Macro Wizard
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Explore the Macro WizardLearn how to choose a trainer
Review questions to ask, positive signs, red flags, and how to inquire about a True Fit trainer.
Visit Find a TrainerFrequently asked questions
Using your BMR and BMI estimates
Who is this BMR and BMI calculator for?
This calculator is designed for adults age 20 and older. BMI is interpreted differently for children and teenagers, and pregnancy, certain medical conditions, body composition, and other circumstances may make these estimates less useful.
Why does the BMR calculator ask me to choose an equation?
The Mifflin–St Jeor equation uses different constants for female and male physiology. The selection is used only in the browser calculation and is not stored or submitted.
Is BMR my daily calorie target?
No. Activity level is not included. BMR estimates resting energy needs before everyday movement, work, household activity, exercise, digestion, goals, health considerations, and individual metabolic differences are considered.
Can BMI be misleading for muscular people?
Yes. BMI uses only height and weight and does not directly measure body fat, muscle mass, bone density, fat distribution, fitness, or overall health. Treat it as one screening measure rather than a diagnosis.
Does True Fit save my calculator information?
No. The calculation runs in your browser. The values entered into this calculator are not submitted to or stored by True Fit.
Methodology
BMI categories follow CDC guidance for adults age 20 and older. Resting energy is estimated with the Mifflin–St Jeor predictive equation. Results are rounded for readability.