"How many calories should I eat?" does not have a single universal answer — it depends on your body, activity level, and goal. TDEE (Total Daily Energy Expenditure) is the actual number behind that answer, and understanding how it is calculated makes it much easier to set a realistic target.
Step 1: calculate your BMR (Basal Metabolic Rate)
BMR is the number of calories your body burns at complete rest, just to keep basic functions running. The most commonly used formula is the Mifflin-St Jeor equation:
Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Step 2: apply an activity multiplier to get TDEE
- Sedentary (little to no exercise): BMR × 1.2
- Lightly active (light exercise 1–3 days/week): BMR × 1.375
- Moderately active (moderate exercise 3–5 days/week): BMR × 1.55
- Very active (hard exercise 6–7 days/week): BMR × 1.725
- Extremely active (physical job plus intense exercise): BMR × 1.9
A worked example
A 30-year-old woman, 65 kg, 165 cm, moderately active:
BMR = (10 × 65) + (6.25 × 165) − (5 × 30) − 161 = 650 + 1,031.25 − 150 − 161 = 1,370.25
TDEE = 1,370.25 × 1.55 = ~2,124 calories/day
This is the estimated number of calories she would need to maintain her current weight.
Adjusting TDEE for weight goals
- Weight maintenance: eat at your TDEE.
- Weight loss: a deficit of 500 calories/day below TDEE produces roughly 1 pound of weight loss per week, since 3,500 calories is roughly equivalent to one pound of body fat.
- Weight gain: a surplus of 300–500 calories/day above TDEE is a common starting point for gradual muscle gain.
Why TDEE is an estimate, not an exact number
Both the BMR formula and the activity multipliers are population-based averages, not a measurement of your individual metabolism. Actual calorie needs vary based on factors like muscle mass, genetics, and hormonal factors that no formula fully captures. TDEE is a reasonable, evidence-based starting point — worth adjusting based on your real-world results over several weeks rather than treating as an exact target from day one.
Tip: track your weight weekly rather than daily, and adjust your calorie target if your actual trend doesn't match what your TDEE calculation predicted after 3–4 weeks — this real-world feedback is more reliable than the formula alone.
Getting your number without the manual math
Calculating BMR and then applying the correct activity multiplier by hand is doable but easy to make small errors in. CalcMastermind's Calorie Calculator handles both steps at once and adjusts automatically for weight loss or gain goals.
The bottom line
TDEE combines your resting calorie burn with your activity level to estimate your true daily calorie needs — a useful, evidence-based starting point that is worth refining based on how your body actually responds over time.