How to calculate TDEE in three steps
A useful result depends more on honest inputs and careful interpretation than on extra decimal places.
1. Enter current measurements
Use your current age, height and a recent weight. Imperial values are converted to centimetres and kilograms before the equation runs. Body weight shifts with hydration and digestion, so one measurement is enough to begin, while an average of several comparable mornings may better represent you.
2. Select coefficients and activity
Choose the biological coefficient set required by Mifflin-St Jeor, then describe an ordinary week. Include more than workouts: standing work, walking commutes, childcare, errands and household tasks may contribute more energy expenditure than a few short gym sessions.
3. Calculate, observe and refine
The calculator multiplies estimated basal metabolism by the chosen activity factor. Use the result under reasonably stable conditions for two to four weeks. Compare average intake, weight trend, hunger, energy and training performance before making a modest adjustment.
What is TDEE?
TDEE means total daily energy expenditure: all the energy your body uses over 24 hours. It includes basal metabolism, the thermic effect of food, planned exercise and unplanned everyday movement. It is broader than the “active calories” shown after a workout.
Basal metabolism is usually the largest component, supporting breathing, circulation, temperature regulation, cellular maintenance and organ function at rest. The thermic effect covers digestion, absorption and metabolism of food. Exercise is noticeable, but steps, posture, fidgeting, work and errands—often grouped as non-exercise activity thermogenesis, or NEAT—can differ substantially between people.
Expenditure is dynamic rather than fixed. A new job, injury, training block, weight change or unconscious reduction in movement can alter it. An equation is therefore useful for setting an initial reference and making comparisons, but repeated real-world observation is more informative than treating one calculated value as permanent.
The Mifflin-St Jeor equation
Published in 1990, Mifflin-St Jeor estimates resting energy expenditure from weight in kilograms, height in centimetres, age and a biological-sex term. We explicitly call these “female coefficients” and “male coefficients” because they are categories in the original equation, not statements about gender identity.
The resting estimate is multiplied by an activity factor. Frankenfield and colleagues compared predictive equations and found Mifflin-St Jeor generally the most reliable of those studied for non-obese and obese adults. Their review also shows the important caveat: no equation predicts every individual accurately.
Female coefficients: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161.Male coefficients: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5.What the equation cannot know
- It does not directly measure muscle mass, fat mass, spontaneous movement or movement efficiency.
- Individual error can be substantial, especially for athletes, very muscular people, older adults, pregnancy, breastfeeding and some health conditions.
- The activity factor is a simplified category; two people selecting the same level may expend different amounts.
- A formula cannot diagnose a “slow” or “fast” metabolism and cannot guarantee weight maintenance, loss or gain.
Mifflin-St Jeor versus Katch-McArdle
Katch-McArdle estimates resting metabolism from lean body mass: 370 + 21.6 × lean mass in kilograms. It may look more individualised for someone highly muscular or far from average body composition because it does not require age, height or a biological-sex coefficient.
That advantage depends on the quality of the body-fat estimate. Bioimpedance scales, skinfold callipers and even some laboratory methods carry uncertainty. An error of several percentage points directly changes calculated lean mass and the equation result. Without a reliable, recent measurement, Mifflin-St Jeor is often a simpler, more robust starting point.
Both are prediction tools. If they differ, do not automatically pick whichever result better matches your expectation. Test a reasonable reference against several weeks of consistent intake and trend data.
BMR = 370 + 21.6 × FFM (kg)How to choose an activity factor
The physical activity level (PAL) methodology discussed by FAO/WHO/UNU supports estimating energy requirements by multiplying basal metabolism by an activity level. However, the exact conventional five-step scale from 1.2 to 1.9 used by this calculator does not come directly from the FAO report; it is a common practical simplification.
Think in weekly averages. One hard session does not cancel ten seated hours every day, while manual work may raise expenditure without formal exercise. If you sit between two levels, start with the lower one and calibrate against your observed trend. The factor describes typical expenditure; it is not a score or reward for effort.
| Usual activity level | PAL | Consider work, travel, daily tasks and exercise across a representative week. |
|---|---|---|
| Sedentary | ×1.2 | Mostly seated work, little purposeful walking, and no or very little exercise. |
| Lightly active | ×1.375 | Regular daily movement or light exercise around 1 to 3 days per week. |
| Moderately active | ×1.55 | Moderate exercise around 3 to 5 days per week and a reasonably mobile routine. |
| Very active | ×1.725 | Hard training 6 to 7 days per week or a physically demanding occupation. |
| Extremely active | ×1.9 | Hard physical work plus frequent training, or an exceptional training volume. |
Desk job and two short workouts
Light activity is often more realistic than moderate when daily steps are low and weekends are quiet.
Standing job with constant walking
Moderate may fit despite little formal exercise, depending on the duration and physical demand of each shift.
Daily training
Very active also implies substantial volume or intensity. Recovery days, easy sessions and movement outside training still matter.
A worked TDEE example
Consider a 35-year-old, 170 cm, 70 kg person using the female coefficients. Mifflin-St Jeor gives 10 × 70 + 6.25 × 170 − 5 × 35 − 161 = 1,426.5 kcal/day estimated BMR. With moderate activity at 1.55, estimated TDEE is 1,426.5 × 1.55 = 2,211 kcal/day, displayed as about 2,210 after rounding.
This does not mean the person expends exactly 2,210 kcal every day. A busy day may be above it and a rest day below it. The result is a plausible average to test. If average intake near that level accompanies a broadly stable weight over several weeks, it is a useful estimate. A sustained rise or fall suggests actual expenditure differs.
| Usual activity level | 35 · 180 cm · 80 kg | 35 · 165 cm · 65 kg |
|---|---|---|
| Low activity · ×1.2 | 2,110 kcal | 1,610 kcal |
| Light activity · ×1.375 | 2,410 kcal | 1,850 kcal |
| Moderate activity · ×1.55 | 2,720 kcal | 2,090 kcal |
| High activity · ×1.725 | 3,030 kcal | 2,320 kcal |
| Very high activity · ×1.9 | 3,330 kcal | 2,560 kcal |
Three practical ways to calibrate your result
Calibration turns a population estimate into a personal working reference without pretending to measure metabolism directly.
1. Use trends, not isolated days
If weighing is appropriate for you, measure under comparable conditions and review a seven-day average. Water, sodium, glycogen, digestion and menstrual-cycle changes can hide the signal. Compare at least two to four weeks before drawing a conclusion.
2. Make small adjustments
If the trend does not match your intention, change the reference by roughly 100 to 200 kcal per day, then reassess. Large sudden changes are harder to interpret and may affect hunger, energy, recovery and consistency.
3. Record the context
Note major changes in steps, training, sleep, work and food-tracking accuracy. A mismatch between formula and reality is not failure; it simply shows that the model cannot capture every part of your current situation.
Frequently asked TDEE questions
Straightforward answers to common questions after a first calculation.
Is TDEE the same as BMR?
No. BMR estimates energy required at rest. TDEE adds everyday activity, exercise and, indirectly, the thermic effect of food, so it is normally higher than BMR.
Is my TDEE result accurate?
It is an estimate based on population averages and a simplified activity category. Use it as a starting point, then compare it with your own trend over several weeks.
Why does the formula ask for biological-sex coefficients?
The original equation uses different constants derived from female and male biological categories. This selection only supplies a physiological equation input; it does not define gender identity. No simple equation represents every person perfectly.
What level should I choose if I sit at work but exercise?
Assess the whole week: steps, commuting, chores, session duration and intensity. Two or three workouts may not equal moderate activity when the rest of the week is highly sedentary. Start conservatively and calibrate.
Must I eat exactly my TDEE to maintain weight?
Average intake near actual TDEE may support weight stability, but both intake and expenditure vary and are measured imperfectly. Look for a longer-term average rather than matching one exact number daily.
How often should I recalculate?
Recalculate after a meaningful change in weight, occupation, activity or training. Otherwise, your observed trend is more valuable than repeatedly entering unchanged information.
Can I use TDEE to set a calorie deficit?
It can be an initial reference, not a personalised prescription. Needs and risks differ. Seek qualified support for illness, pregnancy, breastfeeding, an eating-disorder history or any clinical concern.
Why does my fitness watch show another number?
Wearables use proprietary sensors and algorithms, and activity-calorie estimates can be imprecise. A disagreement does not prove either value correct. Compare consistent trends rather than single-day numbers.
Is this calculator suitable for under-18s?
No. Inputs are validated for ages 18 to 100. Growth changes energy needs, so children and teenagers require age-appropriate methods and professional guidance when needed.
Scientific sources
References supporting the equation, comparative validation and the broader energy-requirement framework.
- Mifflin et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals. PMID 2305711.View source ↗
- Frankenfield et al. (2005). Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults. PMID 15883556.View source ↗
- FAO/WHO/UNU (2004). Human Energy Requirements. FAO Food and Nutrition Technical Report Series 1.View source ↗
General information only. No result is medical advice, a diagnosis, a prescription or a guarantee of weight change.