This calculator estimates your Total Daily Energy Expenditure (TDEE) — the number of calories you burn in a day including activity — using the Mifflin-St Jeor equation, widely regarded as one of the more accurate predictive formulas for resting metabolic rate.
The formula
For a 30-year-old man weighing 70 kg at 175 cm: BMR = 10×70 + 6.25×175 − 5×30 + 5 = 700 + 1,093.75 − 150 + 5 = 1,648.75, rounded to about 1,649 kcal. At a "moderate" activity multiplier of 1.55, TDEE ≈ 2,556 kcal/day.
Activity multipliers used
| Activity level | Multiplier |
|---|---|
| Sedentary — little or no exercise | 1.2 |
| Light — exercise 1–3 days/week | 1.375 |
| Moderate — exercise 3–5 days/week | 1.55 |
| Active — exercise 6–7 days/week | 1.725 |
| Very active — hard daily exercise or physical job | 1.9 |
Using this number
- Maintain weight: eat approximately your TDEE.
- Lose weight: a common, moderate approach is a deficit of roughly 500 kcal/day below TDEE, which corresponds to about 0.5 kg (1 lb) of loss per week.
- Gain weight: a surplus of roughly 250–500 kcal/day above TDEE is a common moderate starting point.
Common mistakes
- Overestimating activity level. Most people who don't exercise in a structured way most days fall into "sedentary" or "light," not "active."
- Treating the result as exact. Predictive equations like Mifflin-St Jeor carry a margin of error; use the result as a starting point and adjust based on real-world tracking over a few weeks.
This tool provides a general estimate for informational purposes and is not a substitute for advice from a registered dietitian or physician, especially if you have a medical condition affecting metabolism.
Frequently asked questions
What is TDEE?
Total Daily Energy Expenditure is the total number of calories your body burns in a day, including resting metabolism and physical activity.
Which formula does this calculator use?
The Mifflin-St Jeor equation, which is generally considered more accurate than older formulas like Harris-Benedict for estimating resting metabolic rate in most adults.
How accurate is this calorie estimate?
Predictive equations provide a useful starting estimate, typically within about 10% of measured values for most people, but individual metabolism varies — use the number as a starting point and adjust based on real-world results.
References
- World Health Organization — General dietary energy guidance
- National Institutes of Health — Background on the Mifflin-St Jeor equation and energy expenditure