TDEE calculator

What is TDEE?

TDEE stands for total daily energy expenditure — the number of calories your body burns in a typical day, including everything from breathing to walking the dog to thinking hard about something.

It’s the most useful single number in any conversation about food and weight. If you eat fewer calories than your TDEE, you lose weight over time. If you eat more, you gain. Eat about the same, and your weight stays where it is. That’s it. The rest is detail.

What makes TDEE more useful than the related and more famous concept of BMR (basal metabolic rate) is that BMR only accounts for what your body burns at complete rest — the energy it takes to keep you alive if you spent the whole day in a coma. TDEE includes the rest of being a human: walking, fidgeting, digesting your meals, working out, getting up to refill a glass of water. For most people, those things add 20 to 90 percent on top of BMR depending on how active they are.

So when a calorie counter or a fitness app asks “how many calories should I eat?”, what they’re really asking is: what’s your TDEE? Pick a number near it for maintenance, below it to lose, above it to gain.

The number this calculator returns is an estimate. A good estimate, drawn from formulas that have been published, peer-reviewed, and used by registered dietitians for decades — but still an estimate. We’ll talk about what it gets wrong and how to adjust further down the page.

How is TDEE calculated?

Your TDEE is the sum of four things your body does with energy. All four happen automatically — you don’t choose to digest food or fidget — but understanding the pieces helps you understand why two people the same size can have wildly different calorie needs.

Basal metabolic rate (BMR) is the largest chunk, usually 60 to 70 percent of your total. It’s what your body burns just to keep you alive: heart beating, lungs breathing, brain running, cells repairing themselves. BMR scales with size — bigger bodies burn more at rest than smaller ones — and it tends to decline slowly with age as muscle mass drops.

The thermic effect of food (TEF) is the energy your body uses to digest, absorb, and store what you eat. It’s small but real, usually 5 to 10 percent of your daily total. Protein costs more to digest than fat or carbs, which is one reason high-protein diets tend to feel more “filling” per calorie.

Non-exercise activity thermogenesis (NEAT) is everything you do that isn’t sleeping or formally working out — walking, typing, fidgeting, standing, gesturing while you talk. NEAT varies enormously between people. A naturally restless person can burn hundreds more calories a day than someone who sits still, without either one noticing the difference.

Exercise activity thermogenesis (EAT) is what you burn during deliberate workouts. For most people, it’s a smaller slice than they expect — a one-hour run burns maybe 500 to 800 calories, which is real but not transformative. Daily NEAT often outweighs occasional EAT.

This calculator estimates the BMR part directly from a formula, then multiplies it by an activity factor that accounts for the other three components together. That activity factor is the biggest source of uncertainty in the result, which we’ll get to in a minute.

Which formula should you use?

Four different formulas can estimate your BMR, and they don’t always agree. This calculator runs all four so you can see the spread, but if you’re trying to pick one to trust most, the answer depends on who you are.

Mifflin-St Jeor (1990) is the right default for most people. It’s the formula every major textbook of dietetics has recommended since the early 2000s, after a major study (Frankenfield et al., 2005) found it was the most accurate predictor of BMR for the general adult population — both men and women, across a wide range of body weights. If you’re a typical adult with a typical body composition, this is the number to trust. It’s what we display as the hero result.

Harris-Benedict (revised 1984) is the older formula Mifflin-St Jeor replaced. It tends to slightly overestimate BMR, especially in people with higher body fat. It’s still in wide use because it’s been around since 1919 and many calculators haven’t updated. For most users, Mifflin-St Jeor is a better choice — but the numbers are close enough that you’ll get reasonable results from either.

Katch-McArdle is the formula to use if you know your body fat percentage and you’re lean or athletic. Instead of estimating BMR from your total weight, it estimates from your lean body mass — the muscle, bone, and organs that actually drive metabolism. For someone with low body fat and significant muscle, Katch-McArdle is meaningfully more accurate than Mifflin-St Jeor, which can underestimate athletic BMR by 100 to 200 calories.

Cunningham is similar to Katch-McArdle but skews slightly higher. It was derived from a sample of trained athletes, so it’s most accurate for that specific population — competitive lifters, endurance athletes, and people with unusually high muscle mass. For everyone else, it tends to overestimate.

The practical version: most people should use Mifflin-St Jeor. If you’ve had your body fat measured (DEXA scan, BodPod, or a careful skinfold reading) and you’re lean, use Katch-McArdle. Don’t trust anyone — including us — to estimate your body fat by looking at a chart.

How accurate are TDEE calculators?

Within about plus or minus ten percent of reality, most of the time. That’s the honest answer, and most calculators won’t tell you.

A ten percent error on a 2,500-calorie TDEE is 250 calories — about the size of a snack. For someone trying to lose weight, that’s the difference between a real deficit and accidentally eating at maintenance. For someone trying to gain, it’s the difference between visible progress and a stalled scale. Worth taking seriously.

Why so much uncertainty? Two main reasons.

The activity multiplier is mostly a guess. When you pick “moderately active” from a dropdown, you’re choosing a single number (1.55, in our calculator) that tries to represent how much energy you spend on everything outside of pure resting metabolism. But “moderately active” means different things to different people — and even for one person, it varies day to day. Your fidgeting, your standing, your incidental walking, your steps to the bathroom: all of that gets lumped into one multiplier. Researchers studying real-world calorie expenditure have found that two people with identical BMR and identical formal exercise can differ by 500 calories or more per day, just from how much they move otherwise.

BMR itself varies more than the formulas capture. The formulas predict an average BMR for someone with your sex, age, weight, and height. But individual metabolisms genuinely vary — by maybe 5 to 10 percent — based on things the formulas can’t see: thyroid function, muscle composition, recent diet history, genetics. Most people are close to the predicted value. Some aren’t.

What this means in practice: treat your TDEE estimate as a starting point, not a final answer. Eat at that number for two to three weeks. Track your weight. If you’re losing or gaining when you didn’t intend to, adjust by 100 to 200 calories and try again. Your real-world TDEE is whatever number actually keeps your weight stable — the calculator’s job is to get you in the neighborhood.

The flip side: the calculator is good enough to be useful, especially if you’ve never tracked calories before. A 10 percent estimate is far better than the 50 percent estimates most people make in their heads.

How to use your TDEE for weight loss or gain

For weight loss: eat 250 to 500 calories below your TDEE. That’s the standard recommended range, and it works.

A 250-calorie deficit is the “mild” tier in our calculator. It produces roughly half a pound of weight loss per week — slow enough to be sustainable, fast enough to see progress over a few months. Most people find this rate easy to live with: it doesn’t require dramatic food changes, hunger is manageable, and energy levels stay roughly normal.

A 500-calorie deficit is the “moderate” tier, producing about one pound per week. This is the rate most fitness coaches recommend for active people who want results without burning out. It’s sustainable for most adults but requires a bit more discipline — you’ll feel the deficit, especially in the first two weeks while your body adjusts.

Anything beyond 750 calories below TDEE — the “aggressive” tier — is where things get risky. You’ll lose faster, but you’ll also lose more muscle along with fat, your hunger will get harder to manage, and your metabolism will adapt downward as your body tries to defend against the deficit. For most people, aggressive cuts work for two or three weeks and then collapse into binging. We show the number, but recommend against staying there long-term.

For weight gain (lean bulking): eat 250 to 500 calories above your TDEE. The mild surplus produces about half a pound per week, the moderate surplus about a pound. Most of those gains will be a mix of muscle and fat — gaining purely muscle requires being in a slight surplus and doing serious resistance training. Going beyond 500 calories above TDEE doesn’t make muscle grow faster; it just adds more fat to the mix.

Tracking and adjusting: once you’ve picked a target, eat at that number for two to three weeks before you judge whether it’s working. Daily weight is noisy — it can swing two or three pounds based on water, sodium, and digestion — so look at the weekly average, not the daily number. If after two weeks your weight is trending in the direction you wanted at roughly the rate you expected, you’ve got the right number. If not, adjust by 100 to 200 calories and try another two weeks.

Protein matters more than the exact calorie count. During a deficit, eating enough protein (roughly 0.7 to 1.0 gram per pound of body weight) is what preserves your muscle while you lose fat. During a surplus, protein is what builds the new muscle you’re trying to gain. The macros section above gives you a starting point for protein based on your inputs.

Common TDEE mistakes

A few patterns trip people up. Avoiding these will get you better results than any specific calorie number ever could.

Overestimating your activity level. This is the biggest one. Most people pick “moderately active” because they go to the gym three times a week — but if you spend the other 23 hours mostly sitting (desk job, driving, evening on the couch), you’re probably closer to “lightly active.” Picking too high inflates your TDEE by 100–300 calories, which is exactly enough to stall fat loss without it being obvious why. When in doubt, pick one level lower than you think.

Not recalculating after losing weight. Your TDEE drops as you get smaller — a 200-pound person burns more than a 170-pound version of themselves, even at the same activity level. If you lose 20 pounds and keep eating at your original deficit number, you’re now eating at your new maintenance. Weight loss stalls. Plug your current weight back into the calculator every 10–15 pounds you lose.

Eating back exercise calories from a tracker. Fitness watches and apps consistently overestimate workout calorie burn, often by 20–40 percent. If your watch says you burned 600 calories on a run and you eat 600 calories to “earn it back,” you’ve probably just erased most of your deficit. The TDEE multiplier already includes a reasonable estimate of your workouts — don’t double-count.

Treating the calculator output as a precise instruction. This is where the ten-percent uncertainty matters. If the calculator says 2,247 calories and you hit 2,200 some days and 2,350 others, you’re well within the noise. Obsessive precision doesn’t produce better results; it just produces a worse relationship with food. Eat in a range, look at the weekly average, adjust based on what your body actually does.

Ignoring sleep and stress. Both meaningfully affect appetite, fat storage, and metabolic rate. The calculator can’t see them, but they can shift your effective TDEE by hundreds of calories. If you’re sleeping five hours a night and stressed at work, “eat at TDEE minus 500” probably won’t work the way it would for a rested version of you. Fix the lifestyle stuff and the numbers start working.