TDEE Calculator

How to use this calculator

1. Enter your stats exactly as you would for a BMR calculation.
2. Choose the activity level that best matches a typical week.
3. The result is an estimate of the calories needed to maintain your current weight.

The formula

BMR

Mifflin–St Jeor basal metabolic rate

factor

1.2 sedentary → 1.9 very active

How it works

Total daily energy expenditure combines resting metabolism with movement: daily life, exercise, and the small cost of digesting food.

The standard approach multiplies BMR by an activity factor. These factors are population approximations — the sedentary-to-extra-active span (1.2 to 1.9) shows how much activity level dominates the estimate.

Choosing the right activity level

Most people overestimate their activity level, which is the main source of error in TDEE estimates. Sedentary means desk work and little deliberate exercise — it is the correct choice for a majority of office workers even if they feel busy. Lightly active covers one to three sessions a week; moderately active three to five; very active six to seven; extra active means physical labour plus training.

Non-exercise activity — walking, fidgeting, standing, housework — varies enormously between individuals and can differ by hundreds of calories a day between two people with identical gym routines. If you sit for most of the day outside your workouts, choose the lower multiplier.

Using TDEE to set a target

Eating at TDEE maintains weight. A deficit of roughly 15 to 20 percent produces steady fat loss for most people without excessive hunger or muscle loss. A surplus of 10 to 15 percent supports gradual muscle gain when paired with resistance training.

Adequate protein — commonly 1.6 to 2.2 grams per kilogram of body weight for people in a deficit or building muscle — preserves lean mass, which in turn protects your metabolic rate.

Calibrating with real data

Treat the calculated figure as a hypothesis. Eat at that level consistently for two to three weeks, weigh yourself under the same conditions several times a week, and use the trend rather than any single reading.

If weight is stable, the estimate was right. If it drifts, adjust by 100 to 200 calories and repeat. This feedback loop beats any formula, because it measures your actual expenditure rather than a population average.

Limitations of TDEE estimates

TDEE calculators combine a predictive BMR formula with a fixed activity multiplier, and both components carry uncertainty. The BMR portion has roughly a ten percent margin of error on its own, and activity multipliers are broad categories that cannot capture the exact number of steps you took or the intensity of a specific workout. Stacking these two sources of error means a calculated TDEE can realistically be off by fifteen to twenty percent from your true expenditure in either direction.

The estimate also assumes a stable body and routine. It does not account for illness, travel, seasonal activity changes, or hormonal fluctuations that can shift daily energy needs by hundreds of calories without any change in your inputs. Treating TDEE as a precise, fixed number rather than a moving estimate is the most common way people misuse the figure.

How TDEE varies across people and life stages

TDEE naturally declines with age, driven partly by gradual muscle loss and partly by reduced activity levels as people move into less physically demanding routines. Someone who trains hard in their twenties and continues eating the same amount in their fifties, without adjusting for reduced muscle mass and activity, will typically gain weight even though their food intake has not changed.

Body size and composition also drive large differences: a taller or more muscular person burns more calories at rest and during activity than a smaller person doing the identical workout, simply because there is more tissue to move and maintain. Pregnancy, breastfeeding, and certain medical conditions such as thyroid disorders can also shift TDEE meaningfully, which is why these situations usually call for individualised guidance rather than a generic calculator.

Common mistakes when using TDEE

The most frequent mistake is selecting an activity level based on intention rather than actual behaviour — choosing moderately active because you plan to exercise three times a week rather than because you consistently have for months. Another is double-counting exercise: if your activity multiplier already reflects your training, adding tracker-reported workout calories on top inflates the target and stalls progress.

People also often change their target too quickly, dropping calories sharply after a single week of no weight loss, when normal water retention and measurement noise can easily mask real fat loss for a week or two. Weighing inconsistently — different times of day, before and after meals, on different scales — adds noise that makes the calibration process unreliable.

Using the number practically

Start by picking the activity level that reflects your last month of behaviour, not your aspirations, and set an initial calorie target a modest percentage above or below that figure depending on your goal. Give the plan at least two to three weeks before judging it, tracking weight trend, energy levels, and workout performance rather than daily scale readings alone.

Once you have a few weeks of consistent data, adjust the target by small increments — commonly 100 to 200 calories — rather than large swings, and recalculate your baseline TDEE whenever your weight or activity level changes substantially. This iterative approach converges on your real expenditure far more reliably than any single formula-based estimate.

Related metrics and when to seek guidance

TDEE builds directly on BMR and is closely tied to the thermic effect of food, the energy your body spends digesting what you eat, which typically accounts for around ten percent of total intake and is highest for protein. Non-exercise activity thermogenesis (NEAT) — the calories burned through incidental movement — is often the most variable and underestimated component of TDEE between individuals.

If you have a history of disordered eating, a diagnosed metabolic or endocrine condition, are pregnant or breastfeeding, or are not responding to calorie adjustments after a reasonable calibration period, a registered dietitian or physician can assess your situation directly rather than relying on a general calculator formula.

Choosing an activity factor honestly

Most people overestimate their activity level, which inflates the TDEE figure and explains why a supposedly correct intake produces no change.

Base the factor on a typical week including rest days, not on your most active week of the year.

Desk work with three gym sessions is usually light to moderate, not very active, however hard those sessions feel.

Non-exercise movement — walking, standing, fidgeting — varies enormously between people and accounts for much of the spread in real expenditure.

Adjusting from real-world feedback

Track intake and weight for two to three weeks, then adjust the estimate to match observed change rather than trusting the formula.

A deficit of roughly five hundred calories a day corresponds to about half a kilogram of loss per week for most people.

Weight plateaus of a week or two are normal and usually reflect fluid rather than a genuine stall.

Very aggressive deficits cost muscle and adherence, so a moderate one that you can maintain almost always wins over a year.

The components of daily expenditure

Total expenditure combines resting metabolism, the energy cost of digesting food, deliberate exercise, and all the incidental movement of daily life.

Resting metabolism is typically the largest share, often around sixty to seventy percent for someone with a mostly sedentary routine.

Digestion adds roughly ten percent, and protein costs more to process than fat or carbohydrate, which is one reason higher-protein diets feel more satiating.

Incidental movement varies more between individuals than exercise does, and it commonly falls quietly during a prolonged deficit.

Common tracking errors

Underreporting intake is widespread and rarely deliberate: oils, drinks, and untracked bites add up quickly across a week.

Fitness trackers tend to overstate calories burned during exercise, and adding that figure back to a TDEE estimate double-counts activity.

Weighing food rather than estimating portions removes most of the error for anyone whose results are not matching the plan.

Weekly averages of both intake and weight give a far cleaner signal than any single day of either.

When this calculator is useful

• Setting a starting calorie target
• Sanity-checking a diet plan
• Understanding how activity changes energy needs