TDEE Calculator

What is TDEE?

TDEE (total daily energy expenditure) is the total number of calories your body uses in a day. It is the calorie intake at which your weight would stay roughly stable – your maintenance calories. Eating consistently below your TDEE leads to weight loss; eating above it leads to weight gain.

TDEE has four parts:

The TDEE calculator above estimates your BMR with the Mifflin-St Jeor equation – or with the Katch-McArdle equation if you know your body-fat percentage – and multiplies it by an activity factor to estimate TDEE. It also shows approximate calorie targets for slow weight loss, standard weight loss and slow weight gain.

The formulas

Mifflin-St Jeor (default)

Published by Mifflin and colleagues in 1990, this equation predicts resting energy expenditure from weight, height, age and sex:

A 2005 systematic review by Frankenfield and colleagues for the American Dietetic Association compared the common prediction equations against measured resting metabolic rate and found Mifflin-St Jeor to be the most reliable, predicting within 10% of measured values in more people than the alternatives – though still not in everyone. That is why it is the default here.

Katch-McArdle (if you enter body fat)

BMR = 370 + 21.6 × lean body mass (kg), where lean body mass = weight × (1 − body fat % ÷ 100).

This equation uses fat-free mass instead of total weight, so it can be more accurate for people with unusually high muscle mass, such as athletes – provided the body-fat estimate is accurate. Consumer body-fat scales can be several percentage points out, which shifts the result.

Activity multipliers

These multipliers are widely used conventions. They are coarse: two "moderately active" people can differ by several hundred calories a day depending on their job and daily movement. Most people overestimate their activity level, so if you are unsure between two levels, the lower one is usually closer.

Worked examples

• Man, 35, 80 kg, 180 cm, moderately active: BMR = 10 × 80 + 6.25 × 180 − 5 × 35 + 5 = 1,755 kcal. TDEE = 1,755 × 1.55 ≈ 2,720 kcal/day.
• Woman, 30, 62 kg, 165 cm, lightly active: BMR = 620 + 1,031 − 150 − 161 = 1,340 kcal. TDEE = 1,340 × 1.375 ≈ 1,840 kcal/day.
• Man, 55, 90 kg, 178 cm, desk job: BMR = 900 + 1,112.5 − 275 + 5 = 1,743 kcal. TDEE = 1,743 × 1.2 ≈ 2,090 kcal/day.
• Athlete, 85 kg, 12% body fat (Katch-McArdle): lean mass = 74.8 kg; BMR = 370 + 21.6 × 74.8 = 1,986 kcal; with a 1.725 multiplier, TDEE ≈ 3,430 kcal/day.

Typical TDEE ranges

To put your number in context, here are approximate maintenance calories from the Mifflin-St Jeor equation for a 40-year-old at average heights and weights:

Using TDEE to change weight

Losing weight

A common rule of thumb is that 1 kg of body weight corresponds to roughly 7,700 kcal (about 3,500 kcal per pound). On that basis:

These figures are a reasonable starting point for the first few weeks, but research by Kevin Hall and colleagues showed that the simple "3,500 calories per pound" rule overestimates long-term weight loss. As you lose weight, your TDEE falls – a smaller body needs less energy, and the body adapts – so weight loss slows over time even if intake stays the same. Recalculating TDEE as your weight changes, and adjusting based on real-world results, works better than relying on the rule indefinitely.

Very low intakes are hard to sustain and can lead to muscle loss and nutrient shortfalls. The calculator flags targets below about 1,200 kcal (women) or 1,500 kcal (men), levels usually only advised with professional supervision. For a tailored daily target, see the calorie calculator.

Gaining weight or muscle

A modest surplus of 250–500 kcal a day combined with resistance training supports muscle gain while limiting fat gain. Larger surpluses mainly add fat.

How accurate is a TDEE calculator?

No equation can measure *your* metabolism. Prediction equations estimate the average for people like you, and real values differ:

• Individual variation in BMR is around ±10% between people of the same size, age and sex.
• Activity is the biggest unknown. NEAT alone can vary by hundreds of calories a day between people.
• Body composition matters. Muscle uses more energy than fat at rest.
• Health conditions and medicines – thyroid disorders, some antidepressants, steroids, beta-blockers – can change energy expenditure. An under- or overactive thyroid affects BMR; see TSH levels.
• Measured methods – indirect calorimetry for BMR and doubly labelled water for TDEE – are accurate but used mainly in research and specialist clinics.

A practical way to find your real TDEE

1. Use the calculator to get a starting estimate.
2. Eat close to that amount consistently for 2–3 weeks, tracking intake as accurately as you reasonably can.
3. Weigh yourself several times a week under the same conditions and look at the weekly average, because daily weight fluctuates by 1–2 kg with water and food.
4. If your average weight is stable, that intake is your real maintenance. If it is rising or falling, adjust by 100–200 kcal and repeat.

Other BMR equations you may see

Different websites and apps use different equations, which is the main reason TDEE estimates disagree. The most common:

For the first worked example above (man, 35, 80 kg, 180 cm), the original Harris-Benedict equation gives a BMR of roughly 1,830 kcal compared with 1,755 kcal from Mifflin-St Jeor – about 75 kcal higher before the activity multiplier, and about 115 kcal higher after it. Neither is "wrong"; they are different estimates of the same unknown. Picking one equation and adjusting with real-world results is more useful than comparing calculators.

How TDEE changes with age

BMR declines gradually through adult life. In the Mifflin-St Jeor equation, each additional year of age reduces predicted BMR by 5 kcal – so a 60-year-old's BMR is predicted to be about 150 kcal lower than the same person's at 30. Part of the decline reflects loss of muscle mass, and part reflects lower activity. Resistance training and staying physically active help preserve muscle and therefore energy expenditure as people age. A 2021 analysis of doubly labelled water measurements from more than 6,000 people (Pontzer and colleagues) found that, once body size and composition were accounted for, energy expenditure was remarkably stable from about age 20 to 60 and declined after about 60.

NEAT: the hidden part of TDEE

Non-exercise activity thermogenesis – the energy used by everything that is not sleeping, eating or deliberate exercise – varies more between people than any other component. Someone with an active job who walks a lot, stands for much of the day and does housework can burn several hundred more calories than a person of the same size who sits for most of the day, even if both do the same gym sessions.

Ways NEAT shows up in daily life:

• Walking to work, the shops or between meetings.
• Standing rather than sitting for some tasks.
• Taking stairs, carrying shopping, gardening, cleaning.
• Playing with children, walking a dog.

When people eat less to lose weight, NEAT sometimes drops without them noticing – one reason weight loss can slow. Tracking daily steps is a simple way to keep an eye on it.

The thermic effect of food

Digesting and storing food uses energy – about 10% of total intake on a mixed diet. Protein has the highest thermic effect (roughly 20–30% of its calories), carbohydrate is intermediate, and fat is lowest. This is one reason higher-protein diets can be slightly more filling and make weight management a little easier for some people, although the overall difference in TDEE is modest.

BMR vs TDEE vs RMR

Who should not rely on a TDEE calculator

Prediction equations are designed for healthy adults. They are less suitable for:

• Children and teenagers, who need energy for growth.
• Pregnancy and breastfeeding, when needs increase.
• People with significant illness, injury or recent surgery.
• People with an eating disorder or a history of one – calorie counting can be harmful, and support from a health professional is important.
• Older adults with frailty or unintended weight loss.