What is TDEE and why does it matter?

TDEE (Total Daily Energy Expenditure) is the total number of calories your body burns in a day, including your basal metabolic rate plus calories burned through physical activity. Knowing your TDEE helps you set accurate calorie targets for weight loss, maintenance, or muscle gain.

How accurate is the Mifflin-St Jeor equation?

The Mifflin-St Jeor equation is considered the most accurate BMR estimation formula, with studies showing it predicts actual BMR within 10% for most people. It is more accurate than the older Harris-Benedict equation and is recommended by the Academy of Nutrition and Dietetics.

How many calories should I eat to lose weight?

To lose approximately 1 pound per week, eat 500 calories below your TDEE each day. For example, if your TDEE is 2,500 calories, aim for 2,000 calories daily. Never go below 1,200 calories without medical supervision.

Should I recalculate my TDEE as I lose weight?

Yes. As your weight changes, your TDEE decreases because your body requires fewer calories to maintain a smaller mass. Recalculate every 10-15 pounds lost or every 4-6 weeks to keep your calorie targets accurate.

TDEE Calculator — Total Daily Energy Expenditure

What is TDEE?

TDEE stands for Total Daily Energy Expenditure. It represents the total number of calories your body burns in a day, including your Basal Metabolic Rate (BMR) plus calories burned through physical activity, digestion, and daily movement. Knowing your TDEE is the foundation of any nutrition plan — it tells you exactly how many calories you need to maintain your current weight.

TDEE is made up of four components. BMR accounts for 60-70% of your daily burn and represents the calories needed just to keep you alive. The Thermic Effect of Food (TEF) is about 10% of TDEE and represents energy used to digest food. Exercise Activity Thermogenesis (EAT) is structured workouts, and Non-Exercise Activity Thermogenesis (NEAT) is all the informal movement in your day — walking, standing, fidgeting. NEAT alone can vary by 2,000 calories between individuals of similar size, which explains a lot of the mystery of why some people seem to stay lean effortlessly.

How the TDEE Calculator Works

This calculator uses the Mifflin-St Jeor equation, published in 1990 and considered the most accurate formula for estimating BMR in modern populations. The Academy of Nutrition and Dietetics recommends it as the current standard over the older Harris-Benedict equation (1919) and Katch-McArdle formula (which requires knowing your body fat percentage).

The Mifflin-St Jeor Equation

Men:BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women:BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

Your BMR is then multiplied by an activity factor to estimate your total TDEE. The activity factors are based on epidemiological observations of how much more energy active people expend compared to sedentary ones.

Activity Factor Guide

Sedentary (× 1.2): Desk job, little or no exercise. Most office workers fall here even if they exercise occasionally.
Lightly active (× 1.375): Light exercise 1-3 days per week, or a job with some movement. Weekend warriors with desk jobs usually fit here.
Moderately active (× 1.55): Moderate exercise 3-5 days per week. This is serious, consistent training — gym sessions of 45-60 minutes at good intensity, or regular running/cycling.
Very active (× 1.725): Hard exercise 6-7 days per week. Competitive athletes, dedicated bodybuilders, or very active professionals.
Extra active (× 1.9): Hard exercise daily plus a physical job, or training twice a day. Elite athletes, construction workers who also train, etc.

Worked Example

Let's calculate TDEE for a 35-year-old man who is 5'10" (178 cm), weighs 180 lbs (81.6 kg), and exercises 4 days per week (moderately active).

BMR= 10 × 81.6 + 6.25 × 178 − 5 × 35 + 5
= 816 + 1112.5 − 175 + 5
= 1,758 calories/day

TDEE = 1,758 × 1.55 = 2,725 calories/day

So this person maintains his weight eating 2,725 calories per day. He'd eat 2,225 cal for weight loss (500 cal deficit) or 3,025 cal for lean muscle gain (300 cal surplus).

How to Use Your TDEE

Your TDEE is the anchor point for every nutrition goal. Everything else gets calculated from it.

To lose weight: Eat 500 calories below your TDEE for approximately 1 pound of fat loss per week. For slower, more sustainable loss, try 250 cal below. For aggressive (but riskier) loss, up to 750 cal below.
To maintain weight: Eat at your TDEE. Track your weight weekly and adjust up or down by 100-200 cal if you're drifting.
To gain muscle: Eat 300-500 calories above your TDEE for lean muscle gain. Larger surpluses mainly add fat, not muscle.
To recomp (lose fat + gain muscle): Eat at or very slightly below your TDEE while prioritizing protein and training hard. Slower than pure cutting or bulking, but works for beginners and detrained individuals.

Common Mistakes When Using This Calculator

Overestimating activity level

Most people pick too high an activity level. A 30-minute walk three times a week is light, not moderate. Moderate means genuine structured training 3-5 days per week at real intensity. When in doubt, start one category lower. If you're losing weight faster than predicted, you picked right (or you can bump up).

Not validating with real-world data

TDEE calculators produce estimates. Research suggests Mifflin-St Jeor is accurate within 10% for about 70% of people. That means 30% of people will find their actual metabolism differs noticeably from the predicted number. Always validate by tracking weight over 2-3 weeks and adjusting.

Forgetting to recalculate

Your TDEE changes as your weight and age change. Someone who loses 30 pounds will see their TDEE drop by 300-500 calories. Recalculate every 10-15 pounds of weight change, or every 4-6 weeks during an active cut.

Not accounting for NEAT changes

If your lifestyle changes significantly — new job, injury, vacation — your TDEE shifts even if your formal exercise stays the same. A summer where you walk around on vacation can add 500 calories per day to your burn; a month of sick days can drop it by as much.

TDEE vs BMR: What's the Difference?

BMR (Basal Metabolic Rate)is what you'd burn in bed all day doing absolutely nothing — just the calories needed to keep your organs functioning, your brain working, and your body temperature stable. This is the baseline.

TDEE (Total Daily Energy Expenditure) is what you actually burn in a real day, which is always more than BMR. TDEE includes the calories you burn from walking to the kitchen, typing at your computer, going to the gym, digesting food, and every other form of energy expenditure.

For nutrition planning, always use TDEE, not BMR. Eating at BMR would put you in a massive deficit because it ignores all your actual movement.

Why Your Results Might Differ From Reality

If you follow your calculated calorie target for 2-3 weeks and your weight change doesn't match predictions, a few things could be happening:

Your activity level estimate is off. This is the most common issue. Try one category lower and retest.
Your tracking is inaccurate. Studies consistently show people underestimate food intake by 20-40%. Weigh your food with a kitchen scale.
Genetic variation. Individual metabolic rates can vary by 10-15% from predicted values due to thyroid function, muscle mass, and other factors.
Normal water weight fluctuation. A stable week on the scale can hide fat loss masked by water retention. Track weekly averages, not daily weight.
Adaptive thermogenesis. After prolonged dieting, your TDEE can adapt downward beyond predictions. A diet break at maintenance helps reset this.

Ready to plan your meals? Calculate your daily macros based on your TDEE. Want to dive deeper? Read our comprehensive TDEE guide.