TDEE Calculator

Calculator

What TDEE is, and the four things inside it

Total daily energy expenditure is the sum of four separate costs, and knowing which is which explains most of what people find confusing about their own metabolism. The largest is basal metabolic rate: the energy spent keeping organs perfused, the brain running and body temperature stable while you do nothing at all. The FAO/WHO/UNU expert consultation puts it at 45 to 70 per cent of daily total expenditure depending on age and lifestyle: nearer the top of that range for an older or sedentary adult, nearer the bottom for someone who trains hard or works on their feet. Either way it is the biggest single block, which is why a calculator that gets BMR wrong gets everything wrong.

The thermic effect of food is the overhead of digesting, absorbing and storing what you eat. The same consultation puts it at about 10 per cent of basal metabolic rate over a 24-hour period; it is often quoted more loosely as 10 per cent of what you eat, which is a rougher approximation of the same idea. Protein costs the most to process, fat the least, which is one modest reason higher-protein diets are slightly easier to lose weight on. Either way it is real but small, and it shrinks along with your intake during a cut rather than staying fixed.

The last two components are movement. Exercise activity thermogenesis is deliberate training (the hour in the gym, the run, the ride), and it is routinely overestimated: an honest hard hour is often 300 to 500 kcal, less than many people assume and less than a large muffin. Non-exercise activity thermogenesis, or NEAT, is everything else you do while awake: walking to the shops, standing, cooking, carrying, fidgeting, restlessness. NEAT is the component that varies most between two people of the same size, and the overfeeding experiment that made the term famous found that differences in how much people unconsciously increased their spontaneous movement explained most of why some of them resisted gaining fat while others did not. When someone appears to eat anything and stay lean, you are usually looking at high NEAT rather than an exotic thyroid.

• Basal metabolic rate: 45–70% of the daily total, and the part this calculator predicts from an equation.
• Thermic effect of food: about 10% of basal rate over 24 hours, highest for protein.
• Exercise activity: the deliberate training you would write on a timetable.
• Non-exercise activity: everything else you do on your feet, and the biggest source of person-to-person variation.

Choosing your activity level honestly

Most people overrate themselves by one level, which inflates the result by 200–400 kcal, enough to erase a planned deficit. A desk job with a couple of gym visits a week is 'lightly active', not 'moderately'. If in doubt, pick the lower level, eat to that number for three or four weeks, and adjust from what the scale and tape actually do. Your real-world trend is a better calorimeter than any formula.

The multipliers are worth reading literally rather than aspirationally. A factor of 1.2 describes someone whose day is genuinely sedentary: seated work, a car or a short walk to transport, no structured training. A factor of 1.55 describes three to five real training sessions a week on top of an ordinary day, not three planned sessions of which two happen. A factor of 1.9 describes manual labour or twice-daily training: bricklaying, farm work, a competitive swimmer's programme. Almost nobody whose job is done at a desk belongs there, however hard they train in the evening.

The ladder shown with your result exists precisely because this is where the error creeps in. Seeing all five totals at once turns an abstract dropdown choice into a visible difference in kilocalories: the step from 'lightly active' to 'moderately active' is worth a couple of hundred calories a day for most bodies, which is the size of an entire moderate deficit. Choose the lower of two levels that both sound about right, and let a few weeks of weight data promote you if you deserve it.

How accurate a TDEE number is, and why

Prediction equations estimate resting energy expenditure within about 10 per cent of a measured value for most healthy adults. The systematic review that established Mifflin–St Jeor as the default concluded it was the most reliable of the published equations, predicting resting metabolic rate within 10 per cent of measured values in more non-obese and obese individuals than any other, with the narrowest error range. Ten per cent sounds tight until you notice it is 10 per cent of the largest component: a basal estimate can be 150 kcal out before any multiplier touches it.

Then the activity factor multiplies that error and adds its own. Activity factors come from population studies of physical activity level (the ratio of total expenditure, measured with doubly-labelled water, to measured basal rate), and the spread inside any one activity category is wide, because two people who describe their week identically can differ by hundreds of kilocalories in NEAT alone. Stacking a ±10 per cent basal estimate onto a category-level multiplier is why we print ±10–15 per cent, displayed as a ±12.5 per cent band around the headline figure.

It is worth knowing that the multipliers used here are not the only set in circulation. The FAO/WHO/UNU consultation classifies habitual activity as a physical activity level of 1.40–1.69 for a sedentary or light lifestyle, 1.70–1.99 for an active or moderately active one, and 2.00–2.40 for a vigorous one. The 1.2-to-1.9 ladder this calculator uses comes from the older Harris–Benedict tradition and runs lower at the sedentary end. Neither set is wrong; they were built from different populations and defined 'sedentary' differently. That two respectable frameworks disagree about the same lifestyle by 0.2 of a multiplier is the clearest possible argument for treating any single number as a starting point.

So the band is not a disclaimer bolted on to look humble; it is the real resolution of the method. A result of 2,400 kcal honestly means 'probably between about 2,100 and 2,700'. Used as a starting point that a few weeks of data will sharpen, that is genuinely useful. Used as a measured truth to be counted against to the calorie, it will quietly mislead you, and the error is not random, because the people most likely to overstate their activity level are the same people most frustrated when the plan does not work.

Calibrating the number against three or four weeks of your own data

The formula gives you a starting estimate. Your own body gives you the answer, and the arithmetic to extract it is simple. Eat at the calculated maintenance figure for at least three weeks, tracking honestly, and watch a seven-day rolling average of your weight rather than any single morning. If the average is flat, the estimate was right and you now own a calibrated number no formula can match.

If the average is moving, convert the movement into calories. A kilogram of body fat is about 7,700 kcal, so losing 0.25 kg a week is a weekly deficit of roughly 1,925 kcal, about 275 kcal a day. Your true maintenance is therefore around 275 kcal above what you have been eating. Losing 0.5 kg a week means about 550 kcal a day. Gaining works the same way in the other direction. Make the adjustment once, in a single step, then hold the new figure for another three weeks before touching it again.

Three weeks is the minimum because water masks everything shorter. A change of training, a salty weekend, a phase of the menstrual cycle, the glycogen shift when carbohydrate intake moves: each can hide or fake a kilogram for a week or more. Judging a calorie target from five days of scale readings is the single most common reason people abandon a plan that was working.

• 0.25 kg lost per week ≈ a 275 kcal daily deficit; your true TDEE is about 275 kcal higher than you assumed.
• 0.5 kg lost per week ≈ a 550 kcal daily deficit.
• 0.25 kg gained per week ≈ a 275 kcal daily surplus; your true TDEE is about 275 kcal lower.
• Use a seven-day average, compare week three against week one, and change the target once.

What changes your TDEE over time

TDEE is not a constant you calculate once. The largest and most predictable change comes from body weight itself: a smaller body costs less to run and less to move, so every kilogram lost lowers the number by roughly 15 to 25 kcal a day once basal rate and movement cost are combined. This is the honest explanation for most weight-loss plateaus: the deficit did not fail, it closed, because maintenance came down to meet the intake.

Sustained dieting adds a smaller effect on top. Adaptive thermogenesis (reduced spontaneous movement, slightly increased muscular efficiency, hormonal downshifts) typically accounts for another 5 to 15 per cent beyond what body-size change alone predicts. It is real and measurable, and it is also routinely oversold: a headwind rather than the ruined metabolism of internet legend, and one that largely reverses when energy intake returns to maintenance.

Lean mass moves the number the other way, though less dramatically than the marketing suggests. In the standard organ-and-tissue estimates a kilogram of skeletal muscle costs around 13 kcal a day at rest, so adding five kilograms of genuine muscle (years of work for most people) adds perhaps 65 kcal to basal rate. What resistance training actually does during a cut is protect the lean mass you already have, which keeps the basal component from falling faster than it needs to.

Age, illness and medication all shift things. A 2021 analysis of doubly-labelled-water measurements in 6,421 people across 29 countries, aged from eight days to 95 years, found that once you adjust for fat-free mass, total energy expenditure is essentially stable from about age 20 to age 60 and then declines by roughly 0.7 per cent a year. The 'metabolism crashes at 40' story is therefore mostly a story about losing muscle and moving less. Fever raises expenditure sharply; thyroid disorders move it in either direction; some psychiatric and hormonal medications lower it. If your measured trend disagrees violently with every equation, that is worth a conversation with a doctor rather than a smaller number in a calculator.

Using TDEE for a cut, maintenance or a gain

For maintenance, eat around the figure and let the weekly average tell you whether it was right. Maintenance is not a single number but a small range (most people hold weight across a band a few hundred kilocalories wide, because NEAT adjusts quietly in the background), so do not chase precision you cannot measure.

For fat loss, take a percentage below TDEE rather than a fixed number, because a fixed 500 kcal deficit is a mild cut for a large athlete and an aggressive one for a small sedentary person. This site plans cuts at up to 20 per cent below TDEE and will not go deeper: the target is held at 80 per cent of your own expenditure, and at absolute floors of 1,500 kcal for men and 1,200 kcal for women, whichever is higher. Those rails are written into the calculation code, not merely into the copy, because deeper cuts cost muscle and adherence without buying much speed.

For a lean gain, a surplus of about 10 per cent above TDEE is enough to build while keeping most of the gain lean; the evidence supports 0.25 to 0.5 per cent of bodyweight per week as the rate that adds muscle rather than mostly fat. Whichever direction you are going, protein is the lever that decides what the calories become (roughly 1.6 to 2.2 g per kilogram of bodyweight), and resistance training is what tells the body which tissue to keep.

Where TDEE numbers are used professionally

Dietitians use predicted energy requirements constantly, because indirect calorimetry (the only way to actually measure resting metabolic rate) needs a metabolic cart, a trained operator and a fasted, rested patient, and is not available in most clinics. A predictive equation plus an activity or stress factor is the standard substitute, with the clinician adjusting from the weight response they observe, exactly as this page recommends you do.

In clinical nutrition support the same arithmetic decides how much energy goes down a feeding tube or into a parenteral bag, usually with the caveat that critically ill patients are the group in whom prediction equations perform worst. In sports nutrition, expenditure estimates set the intake that is then periodised around training blocks, with carbohydrate moved up and down around sessions rather than one total being held all year. Public health bodies work at the population scale: the FAO/WHO/UNU expert consultation on human energy requirements is built on exactly this structure (a basal rate multiplied by a physical activity level), and every activity-factor table in general circulation, including the one on this page, is a descendant of that idea.

It also appears in places most people never see: catering calculations for hospitals and aged care, ration planning for military and expedition contexts, and the nutrient reference values printed on food packaging, which assume a notional daily intake for an average adult. In every one of those settings the number is treated as a planning estimate that gets corrected by observation, which is the only way any of us should be using it.

How it's calculated

Worked example: a woman of 34, 165 cm and 68 kg, lightly active

1. Start with Mifflin–St Jeor for women: 10 × 68 = 680, plus 6.25 × 165 = 1,031.25, minus 5 × 34 = 170, minus 161.
2. Add it up: 680 + 1,031.25 − 170 − 161 = 1,380.25 kcal per day at complete rest.
3. Apply the 'lightly active' factor: 1,380.25 × 1.375 = 1,897.8, which the page shows as 1,900 kcal, about 7,950 kJ.
4. Apply the error band: 1,897.8 × 0.875 = 1,660 and 1,897.8 × 1.125 = 2,140, so the honest statement is 'probably between 1,660 and 2,140 kcal a day'.
5. Check the cost of the next level up: at 'moderately active' the same body reads 1,380.25 × 1.55 = 2,140 kcal, 240 kcal a day more, most of a moderate deficit, from one dropdown choice.
6. Cross-check the basal rate: revised Harris–Benedict gives 447.593 + 9.247 × 68 + 3.098 × 165 − 4.330 × 34 = 1,440 kcal, about 60 kcal above Mifflin, an ordinary disagreement between equations.
7. Turn it into targets: maintenance 1,900 kcal; a moderate cut at 1,897.8 × 0.8 = 1,520 kcal, comfortably above the 1,200 kcal floor; a lean gain at 1,897.8 × 1.10 = 2,090 kcal.
8. Then calibrate: eat 1,900 kcal for three weeks. If the seven-day average drops 0.25 kg a week, true maintenance is nearer 2,175 kcal and every target above it moves up too.

Where this number is used in the real world

• Dietetic practice, where predicted energy requirements stand in for the indirect calorimetry most clinics do not have, then get corrected from observed weight response.
• Clinical nutrition support, setting the energy provision for enteral and parenteral feeding, with the explicit caveat that prediction equations perform worst in critical illness.
• Sports nutrition, as the baseline that intake is periodised around, moving carbohydrate up and down with training load rather than holding one number all year.
• Weight-management programmes, to set a starting target that is a percentage of the individual's own expenditure rather than a one-size-fits-all deficit.
• Public health and dietary guideline work: the FAO/WHO/UNU human energy requirements framework is built on exactly this basal-rate-times-activity-level structure.
• Catering and food service planning for hospitals, aged care and institutions, where average daily energy needs decide how much food is provisioned.
• Military, expedition and occupational planning, where rations have to cover sustained physical work and underestimating the factor has real consequences.

Frequently asked questions

Keep going

A single number rarely tells the whole story. Alongside the TDEE result, the BMR calculator, the calorie deficit calculator, the calorie surplus calculator, the macros calculator, the calories burned calculator and the weight-loss time calculator each add a different angle on the same measurements. For the reasoning behind the numbers, read TDEE explained, Track without DEXA and BMI vs body fat vs waist.

Sources

1. Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr 1990;51:241–7. doi.org/10.1093/ajcn/51.2.241
2. Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc 2005;105:775–89. doi.org/10.1016/j.jada.2005.02.005
3. FAO/WHO/UNU. Human energy requirements, chapter 5: energy requirements of adults (physical activity level classification). Rome, 2004. www.fao.org/4/y5686e/y5686e07.htm
4. Levine JA, Eberhardt NL, Jensen MD. Role of nonexercise activity thermogenesis in resistance to fat gain in humans. Science 1999;283:212–4. doi.org/10.1126/science.283.5399.212
5. Pontzer H, Yamada Y, Sagayama H, et al. Daily energy expenditure through the human life course. Science 2021;373:808–12. doi.org/10.1126/science.abe5017
6. Rosenbaum M, Leibel RL. Adaptive thermogenesis in humans. Int J Obes 2010;34:S47–55. doi.org/10.1038/ijo.2010.184