Calorie Calculator

Total Daily Energy Expenditure (TDEE) is the number of calories your body burns in an average day — everything from keeping your heart beating to the workout you did this morning. It's the single most useful number for deciding how much to eat, whether the goal is losing weight, maintaining it, or building muscle. This calculator estimates TDEE using the Mifflin-St Jeor equation, then translates it into calorie targets for common goals, plus a starting macro split.

What TDEE actually means

TDEE is built from two pieces. The first is BMR (Basal Metabolic Rate) — the calories your body burns at complete rest, just running your organs, breathing, and maintaining body temperature. BMR typically accounts for 60–75% of total daily burn for most people. The second piece is everything on top of that: digesting food, daily movement (walking, fidgeting, chores), and any deliberate exercise. Multiplying BMR by an activity multiplier folds all of that second piece into a single estimate.

Eating at your TDEE keeps weight roughly stable over time. Eating consistently below it produces weight loss; eating consistently above it produces weight gain. This is a simplification of a more complex physiological process, but it holds up well enough in practice that it’s the standard starting point used by dietitians, trainers, and nearly every nutrition app on the market.

It’s worth being clear about what TDEE is not: it isn’t a measured value for any individual, and it isn’t a guarantee. It’s a population-based estimate, built from formulas derived from group averages. It’s an excellent starting point — far better than guessing — but the real test of accuracy is what happens to your actual weight over several weeks at a given intake, not the formula output alone.

The activity portion of TDEE is itself made up of several distinct pieces that a single multiplier compresses into one number. The thermic effect of food (TEF) — the energy your body spends digesting, absorbing, and metabolizing what you eat — typically accounts for roughly 8–15% of total calories consumed, and varies somewhat by macronutrient (protein has the highest thermic cost, fat the lowest). Non-exercise activity thermogenesis (NEAT) covers everything from fidgeting and posture to walking around the house and standing at a desk; research has shown NEAT can vary by hundreds of calories per day between two people of similar size, which is part of why two people with “identical” stats and the same activity multiplier can still have genuinely different real-world TDEEs. Deliberate exercise is usually the smallest of the three components for most non-athletes, even though it tends to get the most attention.

Why "eat less, move more" is technically correct but incomplete

The energy balance principle underlying TDEE — that sustained calorie surplus produces weight gain and sustained deficit produces weight loss — remains scientifically sound. What it doesn’t capture on its own is that both halves of the equation move each other: a large sustained deficit can quietly reduce NEAT (people fidget and move less when underfed) and increase perceived effort of daily tasks, which is one mechanism behind the “metabolic adaptation” that makes some diets feel harder over time even at a constant calorie target. It’s a good reason to treat any calculated TDEE as an evolving estimate to recheck periodically, rather than a number fixed for life.

The Mifflin-St Jeor formula

This calculator uses the Mifflin-St Jeor equation to estimate BMR, then multiplies by an activity factor to get TDEE.

(W = weight in kilograms, H = height in centimeters, A = age in years.)

Mifflin-St Jeor was published in 1990 and is widely regarded — including by the Academy of Nutrition and Dietetics — as the most accurate general-purpose BMR formula available today, with validation studies showing it tracks measured BMR within about 10% for most adults. It has gradually displaced the older Harris-Benedict equation (1918, revised 1984) as the default recommendation in clinical nutrition practice, largely because its 1990 reference population reflects more contemporary average body composition. This site’s dedicated BMR Calculator compares all three major formulas side by side if you want to see how they diverge for your specific numbers.

Like any regression formula built from height, weight, age, and sex, Mifflin-St Jeor has a known blind spot: it can’t see how much of your weight is muscle versus fat. Two people with identical height, weight, age, and sex can have real BMRs differing by 100–200 calories if one carries meaningfully more muscle than the other, since muscle tissue burns more at rest than fat tissue does. For people who know they carry an atypical amount of muscle relative to their weight — bodybuilders and long-time strength trainees in particular — the Katch-McArdle formula, which uses lean body mass instead of total weight, tends to track more closely with actual measured BMR. It requires a body fat percentage as an input, which is why it isn’t the default here but is available on the BMR Calculator.

Worked example

Using this calculator’s own default example — a 30-year-old man, 175 lbs, 5’10” tall, moderately active (activity factor ×1.55):

From that TDEE, the calculator derives goal calories: roughly 1,728 cal/day to lose about 2 lbs/week, 2,228 cal/day to lose about 1 lb/week, 2,728 cal/day to maintain, and 3,228 cal/day to gain about 1 lb/week. Each of these follows the widely-cited rule that a sustained deficit or surplus of about 500 calories/day corresponds to roughly 1 lb of body weight change per week — an approximation itself (more on that below), but a useful planning anchor.

A second example shows why the safe-minimum floor (covered in detail below) matters in practice. A 45-year-old woman, 100 lbs, 5’0” tall, sedentary (activity factor ×1.2), computes to a BMR of about 1,020 cal/day and a TDEE of about 1,224 cal/day. A 1,000-calorie deficit would mathematically suggest 224 cal/day — far below any safe intake — so the calculator floors both the 2 lb/week and 1 lb/week loss targets at 1,200 cal/day instead, rather than displaying a mathematically “correct” but unsafe number. This is exactly the kind of case the floor exists for: smaller-framed individuals with a lower baseline TDEE, where an aggressive deficit percentage produces an unrealistic and unsafe target.

Choosing an accurate activity multiplier

The activity multiplier is the single biggest lever in this calculation, and it’s also the easiest place to introduce error, since it depends on honest self-assessment rather than a measurement.

A common estimation mistake runs in both directions. People with sedentary jobs sometimes select “moderately active” because they exercise a few times a week, without accounting for how sedentary the other 20+ hours of their day are — a desk job plus three gym sessions a week often lands closer to “lightly active” once the full week is averaged. Conversely, people with physically demanding jobs (nursing, warehouse work, construction, food service) sometimes under-select their activity level because they aren’t thinking of work itself as “exercise,” even though the calorie cost is real either way. When in doubt, the more conservative (lower) multiplier is usually the safer starting assumption, since it’s easier to add calories after a few weeks of tracking than to correct for an inflated estimate.

Calories for weight loss, maintenance, and gain

The “500 calories = 1 lb/week” rule comes from the old approximation that a pound of body fat contains about 3,500 calories of stored energy, so a 500 cal/day deficit over 7 days works out to roughly a 3,500 cal weekly deficit — one pound. This is a useful planning heuristic, not a precise biological law: actual weight change also reflects water retention, glycogen stores, and metabolic adaptation, none of which are perfectly linear with calorie intake. It’s a reasonable starting estimate, best refined by comparing it against your own real-world weight trend over several weeks.

This calculator shows four goal levels: a more aggressive 2 lb/week loss (1,000 cal/day deficit), a moderate 1 lb/week loss (500 cal/day deficit), maintenance (your TDEE), and a 1 lb/week gain (500 cal/day surplus). Larger deficits are not automatically better — more aggressive calorie restriction increases the risk of muscle loss, fatigue, and difficulty sustaining the plan long enough to see results, which is a major reason many nutrition guidelines favor moderate, sustainable deficits over aggressive ones for most people.

Why there's a safe minimum calorie floor

This calculator never shows a goal calorie target below 1,200 cal/day for women or 1,500 cal/day for men, even when a large deficit would otherwise compute to a lower number. These figures reflect commonly cited general guidance — not a universal medical rule — for the lowest intake most healthy adults can sustain without a meaningfully elevated risk of nutrient deficiencies, muscle loss, and other complications from prolonged very-low-calorie eating.

For most adults with an average or higher TDEE, this floor never comes into play — it only matters for smaller-framed individuals, older adults, or anyone with a lower baseline TDEE, where an aggressive deficit could otherwise land below a safe minimum. Anyone who calculates a “natural” goal near or below these floors, or who is considering a significant, sustained calorie restriction for any reason, is better served working directly with a doctor or registered dietitian, who can account for individual health history in a way a formula cannot.

Suggested macro split at maintenance

Alongside total calories, this calculator suggests a general-purpose 40/30/30 macro split (carbohydrates/protein/fat, by percentage of calories) at your maintenance calorie level, using standard conversions: 4 calories per gram of carbohydrate or protein, and 9 calories per gram of fat.

This split is a reasonable general starting point, not a fixed prescription — individual macro needs vary by body composition goal, activity type, and personal preference. Protein needs in particular are often better set independently, based on body weight and training goal rather than a flat percentage; this site’s Protein Calculator and Macro Calculator both offer a more tailored breakdown if the 40/30/30 default doesn’t fit your situation.

Why TDEE estimates vary between people and tools

If you’ve calculated your TDEE on more than one calculator and gotten different numbers, that’s expected rather than a sign something is broken. Different tools use different BMR formulas (Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle are the three most common, and they don’t agree with each other by design — each was built from a different reference population). Activity multiplier definitions also vary slightly between sources, and some tools build in an additional buffer or rounding convention that others don’t. A spread of a few hundred calories between two reasonably-built calculators, for the same person, is normal rather than alarming.

Beyond formula choice, real individual variation in metabolism — driven by genetics, muscle mass, thyroid function, and other factors no formula can see — means any calculated TDEE is an estimate with real uncertainty, commonly cited as roughly ±10–20% even for well-validated formulas. This isn’t a reason to distrust the calculation; it’s a reason to treat it as a starting point rather than a fixed target.

Using TDEE as a starting point, not a fixed target

The most reliable way to use any TDEE estimate is to treat it as a first approximation, then refine it against real-world results. Tracking actual food intake (with an app or a simple log) alongside body weight for two to three weeks at a given calorie target shows whether weight is actually trending the direction the formula predicted. If not, the target can be adjusted up or down from there — this real-world feedback loop will always be more accurate for a specific individual than any formula alone, since it accounts for everything the formula can’t measure directly.

Because calorie and macro planning touches directly on nutrition, body weight, and body image, it’s worth being direct: this calculator and the numbers it produces are informational tools meant to support a broader picture of health, not a basis for restrictive eating patterns. Anyone with a complicated relationship with food, exercise, or body image — or anyone considering a significant, sustained calorie restriction — is better served working with a doctor or registered dietitian who can account for individual health history in a way no calculator can.