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The TDEE (Total Daily Energy Expenditure) Calculator estimates the total number of calories your body burns in a 24-hour period by combining your Basal Metabolic Rate (BMR) with an activity multiplier. BMR represents the energy needed for basic life-sustaining functions like breathing, circulation, and cell repair, while the activity factor accounts for all physical movement from walking to structured exercise. The Mifflin-St Jeor equation, developed in 1990, is considered the most accurate BMR formula for the general population, surpassing the older Harris-Benedict equation by approximately 5%. Knowing your TDEE is the foundation of any calorie-based nutrition plan — eat below it to lose weight, at it to maintain, or above it to gain.
TDEE = BMR × Activity Factor, where BMR (Mifflin-St Jeor) = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(years) + s (s = +5 for males, -161 for females)
- 1Enter your biological sex, as the Mifflin-St Jeor equation uses different constants for males (+5) and females (-161).
- 2Input your weight in kilograms (or pounds, which the calculator converts to kg).
- 3Input your height in centimeters (or feet/inches, converted automatically).
- 4Enter your age in years — BMR decreases approximately 1-2% per decade after age 20.
- 5Select your activity level from five tiers: sedentary (×1.2), lightly active (×1.375), moderately active (×1.55), very active (×1.725), or extremely active (×1.9).
- 6The calculator first computes your BMR using the Mifflin-St Jeor formula, then multiplies by the activity factor to produce your TDEE.
- 7Results show your TDEE plus calorie targets for fat loss (-500 cal), maintenance, and lean gain (+250-500 cal).
BMR = 10(65) + 6.25(165) - 5(30) - 161 = 650 + 1031.25 - 150 - 161 = 1,370 cal. TDEE = 1,370 × 1.2 = 1,644 cal. She would eat ~1,144 cal for a 500-cal deficit or ~1,644 to maintain.
BMR = 10(85) + 6.25(180) - 5(28) + 5 = 850 + 1125 - 140 + 5 = 1,840 cal. TDEE = 1,840 × 1.725 = 3,174 cal. Rounding accounts for the approximation. This individual needs over 3,100 cal just to maintain weight.
BMR = 10(70) + 6.25(160) - 5(50) - 161 = 700 + 1000 - 250 - 161 = 1,289 cal. TDEE = 1,289 × 1.55 = 1,998 cal. Age reduces BMR significantly compared to the same stats at age 30.
Personal trainers setting calorie targets for clients beginning fat-loss or muscle-gain programs.
Registered dietitians designing medically supervised weight management plans.
Athletes in weight-class sports (wrestling, boxing, MMA) managing body weight for competition.
Researchers conducting nutrition studies that require baseline energy expenditure measurements.
Meal delivery services calculating daily calorie allotments for subscription plans.
Obese Individuals (BMI > 35)
The Mifflin-St Jeor equation may overestimate BMR in severely obese individuals because excess adipose tissue is less metabolically active than lean mass. The Katch-McArdle formula using lean body mass, or applying a 10-15% reduction to the Mifflin-St Jeor result, may be more appropriate.
Elderly Adults (75+)
BMR declines significantly with age due to loss of muscle mass (sarcopenia) and hormonal changes. The Mifflin-St Jeor equation was validated primarily on adults aged 19-78. For those over 75, actual TDEE may be 10-20% lower than predicted, so indirect calorimetry is recommended when available.
NEAT Variability
Non-Exercise Activity Thermogenesis (NEAT) — fidgeting, walking, standing, and other non-exercise movement — can vary by 500-900 calories per day between individuals. This is the largest source of TDEE estimation error and explains why two people with similar stats can have very different actual expenditures.
| Activity Level | Multiplier | Description | Example |
|---|---|---|---|
| Sedentary | 1.2 | Little or no exercise, desk job | Office worker, no gym |
| Lightly Active | 1.375 | Light exercise 1-3 days/week | Walking, yoga 2-3x/week |
| Moderately Active | 1.55 | Moderate exercise 3-5 days/week | Jogging, cycling 4x/week |
| Very Active | 1.725 | Hard exercise 6-7 days/week | Daily gym + active job |
| Extremely Active | 1.9 | Very hard exercise + physical job | Athlete, construction worker |
Which BMR formula is most accurate?
The Mifflin-St Jeor equation is considered the gold standard for the general population. The Katch-McArdle formula can be more accurate if you know your body fat percentage, as it uses lean body mass directly.
How accurate is the activity multiplier?
Activity multipliers are estimates with a margin of error around 10-20%. For greater precision, use a fitness tracker or heart rate monitor to measure actual exercise calories and add them to a lower base multiplier.
Does TDEE change as I lose weight?
Yes. As you lose weight, both your BMR and TDEE decrease because there is less body mass to sustain. This is why weight-loss plateaus occur and periodic recalculation is essential.
What is adaptive thermogenesis?
When you eat in a deficit for extended periods, your body can reduce TDEE beyond what weight loss alone would predict — by 5-15%. This metabolic adaptation is why diet breaks and refeeds are recommended every 8-12 weeks.
Can I use TDEE if I'm pregnant?
Pregnancy increases energy needs by approximately 340 cal/day in the 2nd trimester and 450 cal/day in the 3rd. Add these amounts to your pre-pregnancy TDEE, but consult your OB-GYN for personalized guidance.
Pro Tip
If you suspect the calculator overestimates your TDEE, eat at the calculated maintenance level for 2 weeks while weighing yourself daily. If your weight stays stable, the number is accurate. If you gain, reduce by 100-200 cal and retest.
Did you know?
Your brain alone consumes about 20% of your BMR — roughly 320 calories per day — despite making up only 2% of your body weight, making it the most energy-hungry organ per unit mass.