The Ultimate Guide to Calculating Your TDEE and BMR
If you are trying to lose weight, gain muscle, or simply maintain your current physique, understanding your calorie needs is non-negotiable. You have probably heard the terms BMR and TDEE thrown around in fitness communities. But what do they actually mean, and how do you calculate them? In this ultimate guide, we will break down the math behind your metabolism so you can stop guessing and start tracking your nutrition accurately.
Skip the Math
Don't want to do the algebra by hand? Use our free calorie deficit calculator to instantly find your exact BMR, TDEE, and weight loss targets.
Table of Contents
What is BMR (Basal Metabolic Rate)?
Your BMR is the number of calories your body needs to survive at complete rest. Imagine you were in a coma, sleeping all day. Your body would still need energy to pump blood, breathe air, grow cells, and keep your brain functioning. That baseline energy requirement is your BMR.
For the average person, BMR accounts for about 60% to 70% of the total calories burned each day. This is why severely restricting calories (eating below your BMR) can be dangerous—your body will actually slow down your metabolism to conserve energy, thinking it is starving.
What is TDEE (Total Daily Energy Expenditure)?
Since you are not in a coma, you burn calories doing other things throughout the day. TDEE takes your BMR and adds the calories you burn through daily activities, exercise, and even digesting food.
Your TDEE is your "maintenance level." If you eat exactly your TDEE in calories every day, your weight will stay exactly the same. If you eat more than your TDEE, you will gain weight. If you eat less, you will lose weight.
The Mifflin-St Jeor Formula
In 1990, a scientist named Mifflin published a study that created the most accurate mathematical formula for estimating BMR without clinical equipment. The Mifflin-St Jeor equation looks like this:
Women: BMR = (10 × Weight in kg) + (6.25 × Height in cm) - (5 × Age) - 161
If you do not know your exact body fat percentage, this formula is the gold standard. However, if you know your body fat percentage, you can use the Katch-McArdle formula, which is even more accurate because it uses your lean body mass instead of total weight. You can find your body fat percentage using our body fat calculator.
Activity Multipliers Explained
To get from BMR to TDEE, you have to multiply your BMR by an "activity multiplier." Be honest with yourself here—most people overestimate how active they are.
| Activity Level | Description | Multiplier |
|---|---|---|
| Sedentary | Desk job, little to no exercise | BMR × 1.2 |
| Lightly Active | Light exercise 1-3 days/week | BMR × 1.375 |
| Moderately Active | Moderate exercise 3-5 days/week | BMR × 1.55 |
| Very Active | Hard exercise 6-7 days/week | BMR × 1.725 |
| Extra Active | Hard daily exercise & physical job | BMR × 1.9 |
If you have a desk job but go to the gym for an hour a day, you are likely "Lightly Active" or "Moderately Active," not "Very Active."
Tracking Your Overall Health?
While calories dictate weight, your BMI calculator can help you see where that weight places you on the health scale.
How to Use TDEE for Weight Loss
Once you know your TDEE, weight loss becomes simple mathematics. One pound of body fat contains roughly 3,500 calories. To lose 1 pound per week, you need to create a daily deficit of 500 calories.
For example, if your TDEE is 2,500 calories, you would eat 2,000 calories a day to lose 1 pound a week. It is highly recommended not to exceed a 1,000 calorie daily deficit (2 lbs per week), as this can lead to muscle loss and metabolic adaptation. If you are following a low-carb diet, you can use our keto macro calculator to ensure you are hitting your protein and fat targets while in a deficit.
Frequently Asked Questions (FAQ)
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest just to keep your organs functioning. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by your daily activity level, representing the total calories you burn in a day.
Should I eat my BMR or TDEE to lose weight?
To lose weight, you should eat slightly below your TDEE (usually a 500 calorie deficit). You should generally avoid eating below your BMR, as doing so can slow down your metabolism and lead to muscle loss and nutrient deficiencies.
What is the most accurate BMR formula?
The Mifflin-St Jeor equation is widely considered the most accurate BMR formula for the general population. If you know your exact body fat percentage, the Katch-McArdle formula can be even more accurate as it relies on lean body mass.