Health & Medicine · Dietetics
TDEE Calculator
Calculate your Total Daily Energy Expenditure (TDEE) using the revised Harris-Benedict equation and activity multiplier.
Calculator
Formula
The revised Harris-Benedict equations (Roza & Shizgal, 1984) estimate Basal Metabolic Rate (BMR) — the energy expended at complete rest. TDEE is then obtained by multiplying BMR by an activity factor ranging from 1.2 (sedentary) to 1.9 (very active). W = weight in kg, H = height in cm, A = age in years.
Source: Roza AM, Shizgal HM. The Harris Benedict equation reevaluated. Am J Clin Nutr. 1984;40(1):168-182.
How it works
TDEE is calculated in two steps. First, Basal Metabolic Rate (BMR) is estimated using the revised Harris-Benedict equations — the most widely validated equations for non-athlete adults. BMR represents the energy required to sustain basic physiological functions at rest: breathing, circulation, thermoregulation, and cell production.
Second, BMR is multiplied by an activity factor (the Katch-McArdle multiplier) to account for physical activity and the thermic effect of food. Activity factors range from 1.2 for completely sedentary individuals to 1.9 for athletes in two-a-day training programmes.
The result is your TDEE — the caloric intake required to maintain your current body weight. To lose weight, consume 300–500 kcal below TDEE. To gain weight, consume 300–500 kcal above it.
Worked example
A 35-year-old male, 80 kg, 180 cm, moderately active (activity factor 1.55):
BMR = 13.397 × 80 + 4.799 × 180 − 5.677 × 35 + 88.362 = 1,882 kcal/day
TDEE = 1,882 × 1.55 = 2,917 kcal/day
To lose approximately 0.5 kg per week, this individual should target around 2,417 kcal/day (500 kcal deficit).
Limitations & notes
The Harris-Benedict equations were derived from measurements of healthy adults and may be less accurate for individuals with extreme body compositions (very obese or very lean/muscular). The Mifflin-St Jeor equation (1990) is considered slightly more accurate for obese populations.
Activity multipliers are estimates. Individual variation in non-exercise activity thermogenesis (NEAT) can cause actual TDEE to differ by 200–400 kcal/day from calculated values. Adjust based on real-world weight change over 2–3 weeks.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the energy your body requires at complete rest to sustain vital functions. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor to account for physical activity and the thermic effect of food. TDEE is always higher than BMR.
How accurate are TDEE calculators?
Population-level TDEE equations have a standard error of approximately ±10–15% for individuals. This means your actual TDEE may be 200–400 kcal above or below the calculated value. Track your actual weight change over 2–3 weeks and adjust your intake accordingly for personalised calibration.
Should I eat at my TDEE to maintain weight?
Yes — consuming calories equal to your TDEE over time will maintain your current body weight. In practice, aim within ±100 kcal of TDEE, as precise daily matching is neither necessary nor practical. Focus on weekly averages rather than day-to-day precision.
What activity level should I choose?
Be honest and slightly conservative. Most office workers with 3–4 exercise sessions per week fall into 'Lightly active' (1.375) or 'Moderately active' (1.55). Avoid selecting 'Very active' unless you genuinely train 6–7 days per week at high intensity. Overestimating activity is the most common TDEE calculation error.
Does TDEE change as I lose weight?
Yes. As body weight decreases, both BMR and TDEE decrease. Recalculate every 5–10 kg of weight change to update your caloric targets. Metabolic adaptation (adaptive thermogenesis) can also reduce TDEE beyond what weight loss alone predicts, particularly during extended caloric restriction.
Last updated: 2025-01-15 · Formula verified against primary sources.