How to calculate your TDEE, step by step

Step 1: find your BMR with Mifflin-St Jeor

Your BMR (basal metabolic rate) is roughly what your body burns at rest — just staying alive, no movement included. The formula most dietitians default to is Mifflin-St Jeor, from a 1990 study of nearly 500 people that's held up better than the older Harris-Benedict equation in later validation work (Mifflin et al., American Journal of Clinical Nutrition, 1990; a 2005 systematic review of predictive equations found it the most accurate of the ones tested, Frankenfield et al., J Am Diet Assoc):

Plug in kilograms and centimeters, not pounds and inches — if you only know pounds, divide by 2.2; for inches, multiply by 2.54.

Step 2: multiply by your activity level

BMR alone ignores everything you actually do in a day. TDEE (total daily energy expenditure) accounts for that by multiplying BMR by a factor for your activity level:

Pick the row that matches your actual week, not your aspirational one. This part is where most people overestimate — "I go to the gym sometimes" usually means the 1.2 or 1.375 row, not 1.55. Be honest here; the whole calculation hinges on it.

TDEE = BMR × multiplier. That number is roughly how many calories you'd eat to hold your current weight steady.

Worked example, start to finish

Take a 35-year-old woman, 68 kg, 165 cm, who works a desk job and does light exercise 2–3 times a week:

1. BMR = 10 × 68 + 6.25 × 165 − 5 × 35 − 161 = 680 + 1,031.25 − 175 − 161 = 1,375 kcal
2. Multiplier for "light exercise, 1–3x/week" = × 1.375
3. TDEE = 1,375 × 1.375 ≈ 1,891 kcal/day

That's her maintenance number — what she'd eat to stay the same weight. To lose weight, she'd eat below it (a common, moderate starting point is a 500 kcal/day deficit for roughly 0.5 kg/week of loss, though the right deficit depends on her goals and how much weight she has to lose — see how to figure out a calorie deficit that actually fits your situation). To gain, she'd eat above it.

Where this number breaks down (and what to do about it)

Here's the part most calculators don't tell you: Mifflin-St Jeor is a population average, not a measurement of you. It was derived by fitting a formula to nearly 500 people — if your metabolism sits at either tail of that distribution (and someone's metabolism always does), the formula will be off for you specifically, sometimes by a few hundred calories in either direction.

That's not a reason to skip the math — it's still the best starting estimate you have without a metabolic chamber. But treat the number as a starting point, not gospel. The real-world fix is simple: eat at your calculated TDEE (or your target deficit/surplus) for 2–3 weeks, track your actual weight trend, and adjust. If you're not losing at a deficit that should be working, your real TDEE is probably lower than the formula said — eat a bit less or move a bit more. The formula gets you in the right neighborhood fast; your own data corrects the rest.

How Bocco uses this number

I built Bocco so nobody has to do this arithmetic by hand every time their weight or activity level changes. You enter your stats once during onboarding, and the app runs the exact Mifflin-St Jeor + activity-multiplier calculation above to set your daily target automatically — then keeps it current as your weight and age change. It's the same formula, just without the calculator.