How to Calculate Your TDEE

Your TDEE (Total Daily Energy Expenditure) is the total number of calories your body burns in a day. To lose fat, eat 400-600 calories below it. To build muscle, eat 200-300 calories above it. To maintain, match it. Everything in nutrition starts here. Every diet plan, every macro target, every calorie goal is downstream of this one number.

Most people either don't know their TDEE or they're using a wildly inaccurate estimate. Either way, the result is the same: they're flying blind. I calculate TDEE for every coaching client at CoachCMFit before we touch any other nutrition variable, because there is no meaningful plan without an accurate energy baseline.

This guide gives you the exact formula I use, the activity multipliers, a worked example, and the calibration process that turns the estimate into an accurate personalized number over two weeks of tracking.

What TDEE actually measures

TDEE is the sum of four components:

• BMR (Basal Metabolic Rate): The calories your body burns at complete rest just to keep you alive. Organ function, cell turnover, body temperature regulation. This is typically 60-70% of total TDEE for sedentary people.
• NEAT (Non-Exercise Activity Thermogenesis): All movement that isn't structured exercise. Walking to your car, fidgeting, doing dishes, taking the stairs. This is highly variable across individuals and is the component most affected by a caloric deficit (your body reduces NEAT when calories drop, which is why activity levels need to be actively maintained during dieting).
• EAT (Exercise Activity Thermogenesis): Calories burned during structured training sessions. Typically 5-15% of total TDEE for people training 3-5x per week.
• TEF (Thermic Effect of Food): The energy cost of digesting food. Roughly 10% of total caloric intake. Protein has the highest TEF at 20-30%, which is one of many reasons high-protein diets support fat loss.

Most calculators estimate TDEE by calculating BMR and multiplying by an activity factor that represents the sum of NEAT + EAT + TEF. The result is an estimate. A good one, but still an estimate that needs real-world calibration.

The formula: Mifflin-St Jeor

The Mifflin-St Jeor equation is the most validated BMR formula in the research. A 2005 analysis published in the Journal of the American Dietetic Association compared five BMR equations across 166 adults and found Mifflin-St Jeor to be the most accurate, predicting true RMR within 10% for 82% of subjects. That's your starting point.

Worked example

Female, 35 years old, 150 lbs (68 kg), 5'5" (165 cm):

BMR = (10 x 68) + (6.25 x 165) - (5 x 35) - 161 = 680 + 1031.25 - 175 - 161 = 1,375 calories

That's her resting metabolic rate. She burns 1,375 calories per day just existing. Now we apply the activity multiplier.

Activity multipliers: the most common source of error

This is where most people go wrong. They pick "moderately active" because it feels right, when the honest answer is "lightly active" or even "sedentary." The tendency to overestimate activity level is consistent in research, and it leads to calorie targets that are 200-400 calories too high, which is the difference between losing fat and maintaining weight.

Continuing the example: our 35-year-old woman with a desk job who trains 3x per week is lightly active. TDEE = 1,375 x 1.375 = ~1,890 calories per day. Her fat loss target is 1,890 minus 500 = 1,390 calories.

If she had chosen "moderately active" instead, her TDEE estimate would have been 1,984 and her diet target 1,484 calories. That 94-calorie difference seems small but compounds to nearly 650 calories per week of error. Over a month that's 2,600 calories, potentially 0.7 lbs of additional fat she doesn't lose because the estimate was off.

How to calibrate your TDEE in two weeks

The formula gives you a starting point. Real-world data gives you the accurate number. Here's the two-week calibration protocol I use with every CoachCMFit client who is new to tracking:

1. Set your calorie target based on the formula. Use "maintenance" calories (your TDEE estimate, no deficit) for the calibration period.
2. Track every calorie for 14 days using a food scale and a logging app. No eyeballing. The scale is the only way to get accurate data.
3. Weigh yourself every morning under the same conditions (after waking, after using the bathroom, before eating or drinking). Record the number.
4. After 14 days, average your bodyweight for both weeks. Compare week 1 average to week 2 average.
5. If weight stayed the same, your formula estimate was accurate. If weight dropped, your real TDEE is higher than the formula calculated. If weight increased, your real TDEE is lower.

Adjust your estimate based on the data. Every 100 calories of daily discrepancy = roughly 0.2 lbs of weight change per week. Use that math to back-calculate your real TDEE.

When to recalculate

Recalculate every 10-15 lbs of weight change. As you lose fat, your BMR drops because there is less body mass to maintain. This is called metabolic adaptation, and it's why fat loss stalls even in a caloric deficit if you don't adjust your targets over time.

Muscle gain affects TDEE in the opposite direction. More muscle raises BMR, which is why building muscle while dieting helps prevent the metabolic slowdown that kills long-term fat loss. It's also why strength training is non-negotiable in any fat loss phase, not optional.

Practical action steps