Basal Metabolic Rate (BMR)
— kcal/day
Energy your body uses each day at complete rest.
Personal energy, clearly estimated
Daily Energy Needs Calculator
Estimate your BMR, total daily energy expenditure, and calorie targets using the Mifflin–St Jeor formula. Compare maintenance, loss, and gain goals without sending personal data anywhere.
BMR & TDEE estimatesGoal-based calorie ranges
How This Calorie Maintenance Calculator Works
Formula, activity levels, ranges, and limitationsThis calculator turns your age, sex, height, weight, and usual activity into two estimates: the calories your body uses at rest and the calories you may need across a typical day. Here is what each number means and how to use it.
The Mifflin–St Jeor formula
The Mifflin–St Jeor equation estimates basal metabolic rate using 10 × weight (kg) + 6.25 × height (cm) − 5 × age, then adds 5 for males or subtracts 161 for females. The result is an estimate in kilocalories per day—the unit commonly labeled “calories” on food packaging.
BMR vs. TDEE: which number should you use?
BMR is the energy needed for essential functions at complete rest. Total daily energy expenditure (TDEE) starts with BMR and accounts for ordinary movement, exercise, and digestion. If you want to estimate maintenance calories—roughly how much you could eat while maintaining your current weight—use TDEE, not BMR.
How to choose the right activity level
Think about your entire routine, not workouts alone. Include your job, walking, commuting, household tasks, and structured exercise. If two descriptions seem plausible, begin with the lower activity factor and calibrate the result using your real-world trend.
- Sedentary (1.2): office or desk job with little structured exercise.
- Lightly active (1.375): mostly seated work plus exercise 1–3 days per week.
- Moderately active (1.55): an active job or moderate exercise 3–5 days per week.
- Very active (1.725): construction, delivery, or another physical job, or hard exercise 6–7 days per week.
- Extra active (1.9): strenuous labor, twice-daily training, or a competitive athlete routine.
How to use your daily calorie estimate
Treat the result as a starting point rather than an exact prescription. For maintenance, begin near your estimated TDEE. For weight loss or gain, the result cards show example targets 500 calories below maintenance and 300 calories above maintenance. Those offsets do not guarantee a specific weekly change because body weight and energy needs adapt over time.
Keep your intake and routine reasonably consistent, compare weekly average body weight under similar conditions for two to four weeks, and make a small adjustment if the trend does not match your goal. Day-to-day scale changes often reflect water, food, and other short-term factors rather than body-fat change. For a more detailed, time-based projection, use the NIH Body Weight Planner.
Why your actual calorie needs may differ
No equation can directly measure your metabolism. Body composition, non-exercise movement, training load, sleep, health conditions, medications, and changes during weight loss or gain can all affect actual energy needs. Indirect calorimetry performed by a qualified professional is a direct way to assess resting energy expenditure when greater precision is needed.
Editorial and evidence review:
Formula details were checked against the original peer-reviewed
Mifflin–St Jeor research publication
and a
systematic review of resting metabolic rate equations.
Last evidence review: July 23, 2026. This page has not been medically reviewed
and does not replace advice from a qualified health professional.
Important: This calculator is for general informational and
planning purposes only, not medical advice. Avoid aggressive calorie restriction
and consult a qualified health professional for personalized guidance, especially
if you are pregnant, under 18, have a medical condition, take medication that
affects weight or metabolism, or have a history of disordered eating.
Calorie Calculator Frequently Asked Questions
Common questions about BMR, TDEE, and calorie estimates
What is BMR?
Basal metabolic rate, or BMR, estimates how many calories your body uses in a day at complete rest to support essential functions such as breathing, circulation, and temperature regulation.
What is TDEE?
Total daily energy expenditure, or TDEE, is an estimate of the calories you use each day after your BMR is adjusted for everyday movement, exercise, and digestion.
What is the difference between BMR and TDEE?
BMR estimates the calories your body needs at rest. TDEE starts with BMR and adds the energy used for normal movement, exercise, and digestion, so TDEE is the more useful estimate for maintenance calories.
How accurate is the Mifflin–St Jeor formula?
The Mifflin–St Jeor equation is a research-based estimate, not a direct measurement. Actual calorie needs can differ because of body composition, health, medications, training, and other individual factors.
How do I choose an activity level?
Consider your whole week, including work, walking, household activity, and planned exercise. Choose the lower level if you are between two options, then compare your estimated maintenance calories with your weight trend over two to four weeks.
How many calories do I need per day?
Your estimated daily calorie need is the TDEE result. It combines your BMR with the activity level that best represents your typical work, movement, and weekly exercise.
Can I use this calculator for weight loss or weight gain?
Yes, as a starting point. The calculator shows maintenance calories plus example targets 500 calories below maintenance for weight loss and 300 calories above maintenance for weight gain. These are planning estimates, not guaranteed rates of weight change.
Why might my actual calorie needs be different?
The equation cannot directly measure body composition, metabolism, non-exercise movement, training load, health conditions, medications, or changes that occur during weight loss or gain. Use the result as an initial estimate and adjust it using consistent real-world observations.
