Your daily calorie target comes from two numbers: your basal metabolic rate (BMR), the energy you burn at rest, and your total daily energy expenditure (TDEE), that figure scaled up for how active you are. Eat around your TDEE to hold your weight, below it to lose, above it to gain. This guide walks through both numbers with a real example, then shows how to turn them into a target you can actually follow.
BMR: the calories you burn doing nothing
Your basal metabolic rate is the energy your body uses just to stay alive — pumping blood, breathing, keeping your brain and organs running — if you did nothing but rest for 24 hours. For most people, BMR accounts for 60 to 70 percent of all the calories they burn in a day, which is why it's the foundation of any calorie plan.
The most common estimate is the Mifflin-St Jeor equation. For men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5. For women the last term is −161 instead of +5. A 35-year-old man who is 178 cm tall and 80 kg gets 10 × 80 + 6.25 × 178 − 5 × 35 + 5 = 800 + 1,112.5 − 175 + 5, which is about 1,743 calories per day at complete rest.
TDEE: your real daily burn
Nobody spends the whole day motionless, so TDEE multiplies your BMR by an activity factor to reflect how you actually live. The standard multipliers are roughly 1.2 for sedentary (desk job, little exercise), 1.375 for light activity (1–3 workouts a week), 1.55 for moderate (3–5), 1.725 for very active (6–7), and 1.9 for extremely active (hard physical job or twice-daily training).
Take our example man with a BMR of 1,743. If he works at a desk and trains three days a week, moderate activity fits, so 1,743 × 1.55 is about 2,700 calories per day. That's his maintenance number: eat around 2,700 and his weight stays steady over time. Picking an honest activity level matters most here — people routinely overestimate it, which is a common reason a plan stalls.
Turning TDEE into a weight goal
A pound of body fat holds roughly 3,500 calories, so a daily deficit of 500 calories predicts about a pound of fat loss per week. Our example man would eat around 2,200 to lose weight, 2,700 to maintain, and about 3,000 to gain — usually paired with strength training so the added weight is muscle rather than fat.
A safe, sustainable rate is 0.5 to 1 percent of your body weight per week. Cutting far more aggressively backfires: very low intakes cost you muscle, slow your metabolism, and are hard to stick with. It's also worth setting a floor — most guidance suggests not dropping below about 1,500 calories a day for men or 1,200 for women without medical supervision.
Why the numbers are estimates, not laws
BMR and TDEE formulas are population averages, so your real burn can differ by 10 percent or more in either direction depending on genetics, muscle mass, hormones, and even how much you fidget. Treat the calculated number as a well-informed starting point, not an exact measurement carved in stone.
The reliable way to dial it in is to eat at your estimated target for two to three weeks and track your average weight, ignoring day-to-day swings from water and food volume. If the trend isn't moving the way you predicted, adjust by 100 to 200 calories and reassess. As you lose or gain weight your TDEE shifts too, so recalculating every 10 to 15 pounds keeps your target accurate.
Run the numbers yourself
Frequently Asked Questions
What's the difference between BMR and TDEE?
BMR is what you'd burn at complete rest for a full day; TDEE is that number multiplied by an activity factor to include movement, exercise, and digestion. TDEE is always higher and is the number you actually eat around to lose, maintain, or gain weight.
How big a calorie deficit should I aim for?
A deficit of 500 calories a day predicts roughly a pound of fat loss per week, which is a sustainable pace for most people. Larger deficits speed the scale up short-term but tend to cost muscle and are harder to maintain, so err toward moderate.
How often should I recalculate my calorie needs?
Recalculate every time your weight changes by about 10 to 15 pounds, since your BMR and TDEE both shift as your body size changes. Also revisit the numbers if your activity level changes substantially, such as starting or stopping a training program.