How to Calculate Your TDEE for Weight Loss (No Math Degree Required)

Your TDEE (Total Daily Energy Expenditure) is the total number of calories you burn in a typical day. Get this number right and weight loss becomes math instead of guesswork. Get it wrong, and you'll spend months wondering why you're not losing weight.

The two-part formula

TDEE = BMR × Activity Multiplier

Step 1: Your BMR (Basal Metabolic Rate)

BMR is what you'd burn if you laid in bed all day. The most accurate formula for the general population is Mifflin-St Jeor:

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

Example: 35-year-old man, 180 lbs (82 kg), 5'10" (178 cm):
BMR = (10 × 82) + (6.25 × 178) − (5 × 35) + 5 = 1,762 calories

Step 2: Your activity multiplier

Multiply BMR by one of these based on how active you actually are (be honest):

• 1.2 — Sedentary: desk job, no exercise
• 1.375 — Lightly active: light walks, 1–2 workouts/week
• 1.55 — Moderately active: 3–5 workouts/week
• 1.725 — Very active: 6–7 hard workouts/week or physical job
• 1.9 — Extremely active: elite athlete, manual labor + training

Most people overestimate. If you sit at a desk all day and hit the gym 3 times a week, you're "lightly active" (1.375), not "moderately active" (1.55).

Putting it together

Same 35-year-old man, moderately active:
TDEE = 1,762 × 1.55 = 2,732 calories to maintain weight.

Setting your weight loss target

To lose weight, eat below your TDEE. The size of the deficit determines speed:

• Small deficit (10–15%): 0.5–1 lb/week. Most sustainable. Recommended.
• Moderate deficit (20–25%): 1.5–2 lbs/week. Faster but harder to stick to.
• Aggressive deficit (30%+): 2+ lbs/week. Only for short-term, supervised.

Our 35-year-old at 2,732 TDEE would eat ~2,300 calories for a moderate deficit. He'd lose roughly 0.9 lb/week.

Why most people get this wrong

1. They use online calculators that ignore body composition. A muscular person burns more than the formula predicts. A higher-body-fat person burns less.
2. They overestimate activity. "I went for a walk" doesn't make you moderately active.
3. They underestimate food. A 200-calorie miscount per day = no progress.
4. They don't adjust as they lose. Your TDEE drops as you weigh less. Recalculate every 10 lbs.

The smarter formula (if you know your body fat %)

If you have a DEXA scan, smart scale, or accurate body fat estimate, use Katch-McArdle:

BMR = 370 + (21.6 × lean body mass in kg)

This factors in actual muscle vs. fat, which Mifflin-St Jeor can't. It's significantly more accurate for athletic or higher-body-fat individuals.

The bottom line

Your TDEE is the single most important number in your weight loss journey. Calculate it honestly, eat 10–20% below it, track your food consistently for at least 3 weeks, then adjust based on real-world results — not the calculator.

MyDietingApp calculates your TDEE automatically from your profile (using Mifflin-St Jeor by default, or Katch-McArdle if you've entered lean body mass), then sets your calorie target based on your goal pace. You just eat and log — the math is done.