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How to Calculate Your Daily Calorie Needs
6 min read
Calorie needs are not one-size-fits-all. They depend on your body size, age, sex, and—most importantly—how active you are. The standard approach is a two-step calculation: first your Basal Metabolic Rate (BMR), then your Total Daily Energy Expenditure (TDEE).
Step 1: Basal Metabolic Rate (BMR)
BMR is the energy your body uses at complete rest—just to breathe, circulate blood, and maintain organ function.
Mifflin-St Jeor Equation (most accurate for most adults):
• 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
Example: 30-year-old woman, 65 kg, 165 cm.
BMR = (10 × 65) + (6.25 × 165) − (5 × 30) − 161 = 650 + 1031 − 150 − 161 = 1,370 calories/day
Step 2: Activity Multiplier (TDEE)
Multiply your BMR by an activity factor:
• Sedentary (desk job, little exercise): × 1.2
• Lightly active (light exercise 1–3 days/week): × 1.375
• Moderately active (exercise 3–5 days/week): × 1.55
• Very active (hard exercise 6–7 days/week): × 1.725
• Extra active (physical job + hard training): × 1.9
Using the example above at moderate activity:
TDEE = 1,370 × 1.55 ≈ 2,124 calories/day
This is your maintenance intake—the amount that keeps your weight stable.
Setting a Goal
• Fat loss: Eat 300–500 calories below TDEE. This creates a deficit without extreme restriction. Cutting more than 500–750 calories per day risks muscle loss.
• Weight gain: Eat 250–500 calories above TDEE. A smaller surplus minimizes fat gain.
• Maintenance: Eat near TDEE and adjust over 2–3 weeks based on actual weight changes.
Calorie calculations are estimates. Actual needs vary due to genetics, gut microbiome, and measurement error. Treat TDEE as a starting point and adjust based on results.
Try the Calorie Calculator.
Frequently Asked Questions
How accurate are calorie calculators?
Equations like Mifflin-St Jeor typically predict BMR within ±10% for most people. Treat the output as a reasonable starting estimate and adjust your intake based on real weight changes over 2–3 weeks.
Should I eat back exercise calories?
If you used the correct activity multiplier (which already accounts for exercise), you should not need to "eat back" calories. If you used a sedentary multiplier, then yes, add back a portion of exercise calories.