Free calorie and nutrition tracking
BMR is the number of calories your body burns at rest. TDEE is your total daily calorie need based on your activity level.
BMR, or basal metabolic rate, is the amount of energy your body burns at complete rest over a day. It is the energy that goes purely into staying alive, such as your heartbeat, breathing, brain activity, keeping your body temperature steady and repairing cells. Even if you stayed in bed all day and did not move at all, your body would still burn this much. BMR usually makes up clearly the largest part of daily energy expenditure, often somewhere between 60 and 70 percent, so understanding it is genuinely useful for weight management.
BMR is your resting burn, but few people lie still all day. When BMR is multiplied by an activity factor, you get TDEE, or total daily energy expenditure. It describes everything you actually burn during the day once walking, work, daily chores and exercise are included. TDEE is the figure you build a calorie target around. If you eat at your TDEE, your weight stays roughly the same. If you eat less, weight goes down, and if you eat more, weight goes up. This calculator shows both numbers, so you see your resting burn as well as a realistic estimate of your whole day's needs.
We use the commonly used Mifflin–St Jeor equation. It accounts for weight, height, age and sex, but not factors such as body composition or individual metabolic differences. The equation provides an estimate, not a measurement of resting expenditure. In practice, compare the result with several weeks of tracking.
Many things raise or lower your resting burn. Muscle mass is the most important one you can influence, because muscle uses more energy at rest than fat tissue. That is why strength training and enough protein support your metabolism over the long run. Size and height matter, because a larger body needs more energy. Age lowers expenditure gradually, partly through the loss of muscle mass. There is an average difference between the sexes due to body composition. Prolonged, very low eating can also slow expenditure as the body adapts. For these reasons, treat the calculator's figure as a starting point that you refine through real-world tracking.
The activity factor is where many people overestimate themselves. If your work is sedentary and you rarely move in your free time, you are closer to low activity, even if you walk a few thousand steps. Light exercise two or three times a week moves you to a moderate level. Hard, regular training on several days a week takes you higher. Honesty pays off here, because too high a factor gives too large a target, and the expected result does not follow. If you are unsure, pick the more modest option and adjust it later based on how your weight actually behaves over a couple of weeks.
Once you have a TDEE estimate, use it as a starting point rather than a measured fact. An estimated deficit of 300 to 500 kilocalories per day can be moderate for many adults, but the actual rate of weight change varies. Save the target to your profile, follow your intake and weight trend for several weeks, and avoid drawing conclusions from a single day.
The most common mistake is trusting the calculator's number too precisely and skipping tracking. The figure is an estimate, and your real expenditure only becomes clear once you compare your eating and your weight trend over a few weeks. Another mistake is too steep a deficit, which feels efficient but often leads to hunger, fatigue and slip-ups. A third is overestimating your activity level. If your weight is not moving as expected, check these three things before changing anything dramatically.
Is the BMR calculator free?
Yes, completely free and no sign-in required. You can calculate your numbers right away and, if you like, save the target by signing in.
How accurate is the BMR calculator?
It gives a good estimate that is enough for most people to set a target. A more exact figure would need a laboratory measurement, but in practice tracking corrects the estimate close enough.
Can I eat below my BMR?
It is generally not advisable to set a target below your resting burn for a long period. This is a good place to remember that RestinCal is a tracking tool that does not provide medical advice. Before big changes to your diet, or if you have any medical conditions or special needs, consult a doctor or dietitian.
Sources: Mifflin et al., original equation · NNR 2023, energy