TDEE Calculator

How many calories does your body actually burn each day? Whether your goal is losing fat, building muscle, or simply maintaining your current weight, your total daily energy expenditure (TDEE) is the number that ties everything together. A TDEE calculator takes a few personal details and turns them into a science‑based calorie estimate – without any guesswork.

What Is Total Daily Energy Expenditure (TDEE)?

Total daily energy expenditure is the total number of calories your body burns in 24 hours. It includes everything from keeping your heart beating to running a marathon. TDEE is built from four main components:

• Basal metabolic rate (BMR) – the energy needed for basic functions like breathing, circulation, and cell repair. BMR accounts for 60–75% of TDEE for most people.
• Thermic effect of food (TEF) – the calories used to digest, absorb, and store nutrients. Typically about 10% of your daily intake.
• Exercise activity thermogenesis (EAT) – calories burned during planned exercise sessions. This is the most variable component.
• Non‑exercise activity thermogenesis (NEAT) – energy spent on everything else: walking to the fridge, fidgeting, standing instead of sitting. NEAT can vary by hundreds of calories between two people of the same size.

A TDEE calculator estimates all four components using formulas that have been validated across large populations.

How Does the TDEE Calculator Work?

The calculator uses your age, gender, weight, height, and typical activity level to estimate your daily calorie burn. At its core is the Mifflin‑St Jeor equation – widely considered the most accurate predictive formula for resting metabolic rate in healthy adults. That BMR value is then multiplied by an activity factor that reflects your lifestyle.

The calculator above applies the same Mifflin‑St Jeor equation and the standard activity multipliers shown in the table below. Because it treats activity as a single category, the result is a starting point. Small adjustments based on real‑world changes in weight are normal.

TDEE Formula Explained

The Mifflin‑St Jeor equation uses different constants for men and women because body composition and hormonal profiles differ on average.

For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5

For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161

Once BMR is calculated, multiply by the activity factor that best matches your daily routine:

A 35‑year‑old woman who is 165 cm tall, weighs 68 kg, and exercises moderately 4 times a week would first have a BMR of (10 × 68) + (6.25 × 165) − (5 × 35) − 161 = 1,375 calories. Her TDEE becomes 1,375 × 1.55 = 2,131 calories per day.

The equation was developed from a large dataset of measured metabolic rates and typically falls within 10% of a lab‑tested value. Individual differences in muscle mass, body fat percentage, and genetics mean that any formula is an estimate – but it’s a reliable starting point.

How to Use Your TDEE for Weight Goals

Once you know your maintenance calories, you can create a targeted surplus or deficit depending on your goal.

• Weight loss: Subtract 300–500 calories from your TDEE. This creates a deficit of 2,100–3,500 calories per week, leading to a loss of about 0.3–0.5 kg weekly. Larger deficits often cause muscle loss and a drop in NEAT, which can reduce TDEE faster than expected.
• Weight gain: Add 300–500 calories above TDEE. A surplus of roughly 2,500–3,500 extra calories per week supports 0.25–0.5 kg of gain, ideally combined with resistance training so that the weight comes as muscle rather than fat.
• Maintenance: Eat at your TDEE and monitor weight for 2–3 weeks. If weight trends up or down by more than 0.5 kg, adjust intake by 100–200 calories.

The “3,500‑calorie rule” (3,500 calories = 1 lb of fat) is a simplification. Real fat loss doesn’t follow a straight line because water, glycogen, and muscle mass also shift. That’s why periodic recalculation works better than sticking to one number for months.

Factors That Affect Your TDEE

Body composition. Muscle tissue burns more calories at rest than fat tissue. Two people with the same weight and height can have TDEEs that differ by 200–400 calories solely because of a higher muscle‑to‑fat ratio.

Age. BMR naturally decreases by about 1–2% per decade after age 20, mainly due to loss of lean mass. Staying active and including strength training can slow that decline.

Hormones. Thyroid function, stress hormones like cortisol, and sex hormones all influence metabolic rate. Conditions such as hypothyroidism can lower TDEE by 10–20% below a formula‑based estimate.

Genetics. Research on twins suggests that metabolic rate has a heritable component. Some people simply burn more or fewer calories at rest because of inherited differences in uncoupling proteins and mitochondrial efficiency.

Climate and temperature. Living or exercising in very hot or cold environments can raise calorie burn slightly as the body works to maintain core temperature. The effect is usually modest – up to 5–10% – but may matter for endurance athletes.

This calculator provides estimates based on general formulas. For personalized nutrition or exercise advice, consult a healthcare professional.