Free BMR & Calorie Calculator Online
Use this free online calorie calculator to find your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) in seconds. Instantly see how many calories you burn at rest and how many calories you should eat per day to lose weight, maintain weight, or build muscle - no sign-up required.
Calculated using the Mifflin-St Jeor equation, the formula most widely validated for estimating resting metabolic rate. Results are estimates - individual metabolism varies.
What is BMR and why does it matter?
Your Basal Metabolic Rate (BMR) is the number of calories your body needs just to stay alive if you did nothing but rest in bed all day - breathing, circulating blood, repairing cells, and keeping your organs running. It typically accounts for 60-75% of the total calories you burn in a day, which is why understanding it is the starting point for any weight loss, muscle gain, or maintenance plan. Most free online calorie calculators skip this step and jump straight to a generic daily number, but knowing your actual resting metabolic rate lets you make informed decisions about how aggressive a calorie deficit or surplus is safe for your body.
BMR calculator vs TDEE calculator: how this tool works
This tool works as both a BMR calculator and a TDEE calculator in one. It uses the Mifflin-St Jeor equation, published in 1990 and still considered the most accurate BMR formula for the general population by the Academy of Nutrition and Dietetics. It's more precise than the older Harris-Benedict formula, especially for people who are overweight or very active. Once your BMR is calculated, we multiply it by an activity factor to get your Total Daily Energy Expenditure (TDEE) - your real maintenance calories, including exercise and daily movement. From there, the calculator works as a calorie deficit calculator and calorie surplus calculator, showing daily targets for four common goals: fat loss, maintenance, lean muscle gain, and a faster bulk.
Common searches this calculator answers
- How many calories should I eat to lose weight?
- What is my BMR (Basal Metabolic Rate)?
- How many calories do I burn a day (TDEE)?
- What are my maintenance calories?
- How many calories for a calorie deficit / calorie surplus?
- Free BMR calculator for men and women
How to use the calculator
- Choose metric or imperial units depending on what you're comfortable with.
- Enter your age, weight, and height accurately - small errors here shift the result noticeably.
- Select the activity level that best matches your typical week, not your best week.
- Read your BMR and TDEE from the gauge, then pick the goal card that matches what you're working toward.
Tips for using your results
- Treat the number as a starting point, not a fixed rule. Track your weight for 2-3 weeks at your target calories and adjust up or down 100-200 calories based on real results.
- If you're new to tracking, aim for the maintain number first for a week to calibrate before cutting or bulking.
- Strength training preserves muscle during a calorie deficit better than cardio alone, which matters more than the exact calorie number long-term.
- Very low-calorie diets (under 1200 for women or 1500 for men) are rarely sustainable and can slow metabolism - this calculator will not recommend targets that low.
Frequently asked questions
What's the difference between BMR and TDEE?
BMR is the energy your body burns at complete rest just keeping you alive - breathing, circulation, cell repair. TDEE adds in everything else: walking, exercise, digestion, daily movement. TDEE is the number you actually eat against day to day.
How accurate is this BMR calculator?
The Mifflin-St Jeor equation is typically accurate within about 10% of measured values for most people. Individual results vary based on muscle mass, genetics, and metabolic health, so use this as a starting point and adjust based on real-world results over a few weeks.
Why do the goal numbers differ from just subtracting 500 calories?
A pound of fat is roughly 3,500 calories, so a 500-calorie daily deficit works out to about a pound a week. This calculator uses a slightly more conservative deficit for sustainable fat loss and a smaller surplus for lean gains, to minimize excess fat gain while bulking.
Should I eat the exact same calories every day?
Not necessarily. Many people find it easier to hit a weekly average rather than a strict daily target, eating a bit more on high-activity days and less on rest days. What matters most for weight change is the total over one to two weeks, not any single day.
Does this calculator work for teenagers or older adults?
The Mifflin-St Jeor formula is validated for adults roughly 18 to 65. Teenagers are still growing and have different energy needs, and adults over 65 may see less accurate results due to natural changes in muscle mass and metabolism, so treat results outside that range as a rough guide only.
Is this calculator free to use?
Yes, this BMR and calorie calculator is completely free with no sign-up required, and you can recalculate as many times as you like as your weight or activity level changes.