TDEE Calculator

Understanding TDEE and Basal Metabolic Rate

Your Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a 24-hour period. It accounts for everything from basic organ function and breathing to walking, exercising, and even digesting food. Knowing your TDEE is the foundation of any evidence-based approach to weight management, whether your goal is fat loss, muscle gain, or simply maintaining your current weight.

What Is Basal Metabolic Rate (BMR)?

BMR represents the number of calories your body needs to perform its most basic life-sustaining functions — circulating blood, breathing, cell production, and maintaining body temperature. It is the energy your body would burn if you stayed completely at rest for an entire day. BMR typically accounts for 60-75% of your total daily calorie expenditure, making it the single largest component of TDEE.

This calculator uses the Mifflin-St Jeor equation, which research has shown to be the most accurate predictive equation for estimating BMR in most adults. Published in 1990, it has consistently outperformed older formulas like the Harris-Benedict equation in validation studies. The Mifflin-St Jeor formula calculates BMR using your weight, height, age, and biological sex.

How Activity Level Affects Your Calorie Needs

TDEE is calculated by multiplying your BMR by an activity factor that reflects your overall daily movement and exercise habits. The activity multipliers used in this calculator range from 1.2 for sedentary individuals to 1.9 for very active people:

• Sedentary (1.2x): Minimal movement throughout the day. Typical for office workers who do not exercise regularly. Most daily activity consists of sitting, standing, and light walking.
• Lightly Active (1.375x): Light exercise or sports 1-3 days per week. This might include casual walking, yoga, or light gym sessions a few times per week.
• Moderately Active (1.55x): Moderate exercise 3-5 days per week. This is the category for most regular gym-goers who train with moderate intensity several days per week.
• Active (1.725x): Hard exercise or sports 6-7 days per week. Athletes in training, manual laborers, or people who exercise intensely almost every day fall into this category.
• Very Active (1.9x): Very hard daily exercise plus a physically demanding job. This level is reserved for professional athletes, military personnel in training, or individuals with extremely active lifestyles.

Using TDEE for Weight Management

The fundamental principle of weight management is energy balance. To lose weight, you need to consume fewer calories than your TDEE (a caloric deficit). To gain weight, you need to consume more (a caloric surplus). A deficit of roughly 500 calories per day corresponds to about one pound of fat loss per week, while a 250 calorie deficit produces a more gradual loss of about half a pound per week.

For muscle gain, a moderate surplus of 250-500 calories above TDEE is generally recommended, combined with resistance training and adequate protein intake. Larger surpluses tend to result in excessive fat gain without additional muscle-building benefits.

Limitations and Considerations

While the Mifflin-St Jeor equation is considered the gold standard for BMR estimation, it is still an estimate. Individual metabolic rates can vary by 10-15% due to factors such as genetics, body composition (muscle-to-fat ratio), hormonal status, and metabolic adaptation. People with significantly more muscle mass than average may find their actual TDEE is higher than calculated, while those with less lean mass may find it lower. For the most accurate results, use this calculator as a starting point and adjust your intake based on real-world results over 2-4 weeks.