TDEE Calculator

How TDEE is calculated

Your Total Daily Energy Expenditure is the sum of four components. The largest, comprising 60–75% of total calories burned, is your Basal Metabolic Rate (BMR) — the energy your body consumes at complete rest just to sustain organ function, circulation, and cellular repair. On top of BMR sits the thermic effect of activity (TEA), which covers both intentional exercise and structured movement. The thermic effect of food (TEF) accounts for roughly 8–10% of TDEE; your digestive system burns calories breaking down and absorbing nutrients, with protein costing the most (20–30% of its own calories to process) compared to fat (0–3%). Finally, Non-Exercise Activity Thermogenesis (NEAT) — fidgeting, standing, walking to the kitchen, gesturing while talking — can vary by up to 2,000 kcal/day between individuals at the same body weight, making it the most underrated driver of individual TDEE differences. The calculator above estimates BMR with the Mifflin-St Jeor equation, then scales it by an activity multiplier that approximates the combined contribution of TEA and NEAT at your reported exercise frequency.

The Mifflin-St Jeor formula

In 1990, Mark D. Mifflin and Sachiko T. St Jeor published a landmark validation study in the American Journal of Clinical Nutrition (Mifflin et al., AJCN 1990;51:241–247) that compared five prediction equations against measured resting metabolic rate in 498 adults aged 19–78. Mifflin-St Jeor outperformed the then-dominant Harris-Benedict equation (1919) by a significant margin, predicting RMR within 10% of measured values in roughly 82% of subjects vs. 72% for Harris-Benedict. The equations are:

Male: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5
Female: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161

The −161 intercept for females reflects the average difference in fat-free mass and organ density between sexes at equivalent body weight and height. Mifflin-St Jeor is now the preferred equation in clinical dietetics guidelines from both the Academy of Nutrition and Dietetics and the American Dietetic Association. Its main limitations: accuracy degrades at BMI >35 (tendency to overestimate in severe obesity) and it does not account for exceptionally high muscle mass in strength athletes, where Katch-McArdle — which uses lean body mass instead of total weight — is a better fit.

Activity factor — picking the right one

The activity multiplier, also called the Physical Activity Level (PAL), was systematised by the WHO and FAO and maps your exercise habits to a single scalar applied to BMR. Picking the wrong level is the single biggest source of error in TDEE estimates, so be honest. Sedentary (1.2) means a desk job with no structured exercise — essentially moving only between your bed, chair, and car. Lightly active (1.375) fits someone who exercises 1–3 days per week with moderate-intensity sessions (brisk walking, casual cycling, light gym work). Moderately active (1.55) — the most commonly appropriate level — applies to 3–5 days of purposeful exercise such as gym lifting, running, or team sports. Very active (1.725) is for athletes or manual workers who train hard 6–7 days per week: think competitive swimmers, construction workers, or those doing two-a-day sessions. Extra active (1.9) is reserved for elite athletes or individuals with physically demanding jobs combined with daily training — professional cyclists during stage races, military personnel in active duty, or rowers in competition prep. A common mistake is selecting "very active" simply because you go to the gym five days a week; if sessions are 45–60 minutes of mixed lifting and cardio, "moderately active" is almost always the correct choice.

Cut, maintain, or bulk?

Once you know your TDEE, setting a calorie target is straightforward. To lose fat, a deficit of 500 kcal/day is the clinical benchmark: the long-standing "3,500 kcal per pound of fat" rule predicts roughly 0.45 kg (1 lb) of weight loss per week, which holds reasonably well over the first 4–6 weeks. Beyond that, metabolic adaptation — the body's compensatory downregulation of NEAT and BMR in response to prolonged restriction — reduces actual losses to 60–75% of the theoretical prediction in most people (Hall et al., metabolic adaptation studies, 2012–2016). A 500 kcal deficit therefore remains safe and sustainable while producing meaningful results without the aggressive lean-mass losses associated with larger deficits.

To maintain weight, eat at TDEE. Simple in theory, but remember your TDEE is itself a moving target — it falls as you lose weight (lighter body burns fewer calories) and drifts with changes in daily movement. For a lean bulk, a surplus of 300 kcal/day produces approximately 0.2–0.3 kg/week of total mass gain. Assuming a realistic muscle-to-fat gain ratio of 1:1 for intermediate lifters, roughly half that gain will be lean tissue — meaning around 10–15 g of new muscle protein per day. Larger surpluses (500+ kcal) simply increase fat accrual without meaningfully accelerating muscle protein synthesis, which is limited by training stimulus and hormonal environment, not by calorie surplus alone.

Why your real-world TDEE may differ

Formula-based TDEE is an estimate, not a measurement. Group-level accuracy of Mifflin-St Jeor is ±10%, but individual variance can reach ±20% due to several factors that no equation captures. Metabolic adaptation is the most clinically significant: Hall et al.'s metabolic ward studies demonstrated that sustained caloric restriction triggers a persistent reduction in adaptive thermogenesis — suppressed BMR beyond what weight loss alone predicts — that can persist for years after a diet ends, as famously documented in the six-year follow-up of The Biggest Loser contestants. NEAT is equally variable: research by Levine et al. at the Mayo Clinic showed NEAT differences of up to 2,000 kcal/day between lean and obese individuals of similar size, driven largely by unconscious postural and movement habits. Gut microbiome composition affects caloric extraction from food by 5–10%, and sleep deprivation measurably increases appetite hormones (ghrelin up, leptin down) independent of physical activity. The practical implication: use your calculated TDEE as a starting calorie target, track your actual body weight daily and average it weekly, and adjust by 100–150 kcal every 2–3 weeks until your rate of weight change matches your goal. Your observed TDEE from tracking is always more accurate than any formula.

Related reading

• TDEE — three formulas, three answers
• Metabolic adaptation during a cut
• Six reasons the scale won't move in a calorie deficit
• NEAT — the hidden 200 kcal

Frequently asked questions

What does TDEE mean?

TDEE stands for Total Daily Energy Expenditure — the total number of calories your body burns in a day including BMR, activity, NEAT, and the thermic effect of food. It is the foundation of any calorie-tracking plan.

Which TDEE formula is most accurate?

Mifflin-St Jeor (1990) is the current gold standard, validated against indirect calorimetry to within ±10% for non-obese adults. Harris-Benedict (1919) overestimates by 5-15%. Katch-McArdle is more accurate if you know your body fat %.

How accurate is a calculated TDEE?

Group-level accuracy is ±10%, but individual variance can reach ±15-20% because of differences in NEAT, muscle mass, gut microbiome, and metabolic adaptation history. Treat the number as a starting point and adjust after 2-3 weeks of tracking actual weight change.

How often should I recalculate TDEE?

Recalculate every time your weight changes by more than 5%, your training volume changes substantially, or every 8-12 weeks during sustained weight loss when metabolic adaptation reduces TDEE by 10-15% below the formula prediction.

Should I subtract exercise from TDEE?

No. The activity multiplier already accounts for typical exercise. Adding logged exercise on top double-counts and overestimates calories. Pick the activity level that matches your weekly training and ignore daily workout entries.