Fitly PulseBMR vs TDEE: How Many Calories Do You Need Each Day?
Two terms come up in almost every calorie calculator: BMR and TDEE. Knowing the difference helps you read your results correctly and set a sensible target.
What is BMR?
Basal metabolic rate (BMR) is an estimate of the energy your body uses at complete rest to keep you alive: breathing, circulation, cell repair and temperature control. It is not what you burn in a normal day, because it excludes movement and digestion.
What is TDEE?
Total daily energy expenditure (TDEE) is your estimated total calorie burn over a day. It is your BMR multiplied by an activity factor that reflects how much you move.
| Activity level | Multiplier |
|---|---|
| Sedentary (little or no exercise) | 1.2 |
| Light (1–3 days/week) | 1.375 |
| Moderate (3–5 days/week) | 1.55 |
| Active (6–7 days/week) | 1.725 |
| Very active (physical job) | 1.9 |
The Mifflin-St Jeor equation
Our calculator uses the Mifflin-St Jeor equation, published in 1990 and widely used because it performs well for most healthy adults:
- Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
- Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Worked example
A 28-year-old man, 175 cm and 70 kg, with a moderate activity level:
- BMR = (10 × 70) + (6.25 × 175) − (5 × 28) + 5 = 1,659 kcal
- TDEE = 1,659 × 1.55 = about 2,571 kcal per day
Turning TDEE into a goal
- Maintain weight: eat close to your TDEE.
- Lose fat gradually: a modest deficit, such as around 500 kcal below TDEE, is a common starting point.
- Build muscle: a small surplus, such as 300–400 kcal above TDEE, combined with resistance training.
These adjustments are starting points. The old “3,500 kcal equals one pound” rule is a simplification, because your metabolism adapts as your weight changes.
How accurate is it?
Any equation is an estimate; individual results can differ by roughly 10% or more because of muscle mass, genetics, medications and health conditions. The best approach is to start with the estimate, follow it consistently for two to three weeks, track your weight trend, and adjust.
A note on safety
Very low calorie intakes can cause nutrient deficiencies and other harm and should only be followed under medical supervision. People who are underweight, pregnant, breastfeeding, under 18, or who have a history of disordered eating should seek personalised professional advice rather than relying on a calculator.
Try it yourself — the free Fitly Pulse tracker runs these calculations in your browser. No account needed.
Open the free trackerReferences
- Mifflin MD, St Jeor ST, et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition. PubMed 2305711