Maintenance calories: BMR, TDEE and how to find yours

Calorie calculators give you a starting point, not an answer. Here is how the formulas work and how to use your weight trend to find your real maintenance.

Your maintenance calories are the amount of energy you can eat each day without gaining or losing weight over time. Every cut or bulk is planned around that number, so it is worth understanding where it comes from. The short version: a formula gives you an educated guess, and your scale weight over the next few weeks tells you how good the guess was.

BMR and TDEE

BMR (basal metabolic rate, sometimes called resting energy expenditure) is the energy your body uses at complete rest: keeping your heart beating, your brain working and your temperature steady.

TDEE (total daily energy expenditure) is everything you burn in a day: your BMR plus the energy cost of digesting food, training, walking and general moving about. Expert reports on energy needs work out total expenditure by multiplying BMR by a physical activity level (PAL) ^[4]. TDEE is your maintenance intake.

The two formulas the calculator uses

You cannot measure BMR at home, so calculators predict it from things you can measure. The ETS calorie calculator uses one of two equations.

Mifflin–St Jeor (default)

Published in 1990 from measurements in 498 healthy adults aged 19 to 78, this equation uses weight, height, age and sex ^[1]:

• Men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
• Women: 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161

A systematic review of prediction equations found Mifflin–St Jeor predicted resting energy use within 10% of the measured value in more people, both with and without obesity, than any other equation tested ^[2]. The same review warned that noticeable errors still happen for individuals, and that some age and ethnic groups were poorly represented in the research ^[2].

Katch–McArdle (if you know your body fat)

In the original Mifflin data, fat-free mass was the single best predictor of resting energy use ^[1]. Katch–McArdle builds on that idea and uses lean body mass only ^[3]:

• BMR = 370 + 21.6 × lean body mass (kg)

Lean body mass is your weight minus your fat mass, so you need a body fat estimate. Because it ignores fat mass, it is a sensible choice for muscular lifters who know their body fat. It is only as good as that body fat number, so a rough guess gives a rough answer.

Neither equation is perfect for lifters. A study in male and female athletes found that every prediction equation tested tended to underestimate measured resting metabolic rate ^[5].

Activity factors

Once you have a BMR, the calculator multiplies it by an activity factor to estimate TDEE. The options are:

These factors are broad bands. The FAO/WHO/UNU report on human energy requirements classes even sedentary or lightly active lifestyles at a PAL of 1.40 to 1.69, and notes that PAL values above about 2.40 are hard to sustain long term ^[4]. So if you train hard but sit all day, the honest answer may sit between two options. Your daily steps and job matter at least as much as your gym sessions. Pick the band that matches your whole week, not your best week.

Why the estimate is only a starting point

Several things push your real number away from the formula:

• Individual variation. Two people with the same height, weight and age can differ noticeably in resting energy use ^[2].
• Muscle. Lifters tend to burn more at rest than the equations predict ^[5].
• Activity guesses. The activity bands are wide, and picking the right one is a judgement call ^[4].
• Change over time. As you lose weight and your body adapts, the intake that kept you losing will need adjusting ^[6].

None of this makes the calculator useless. It gets you close enough to start, and then you calibrate.

How to adjust from your weight trend

The most reliable way to find maintenance is to eat a consistent amount and watch what your body weight does.

1. Eat close to your estimated TDEE for 2 to 3 weeks. Aim for consistency rather than perfection, including weekends.
2. Weigh yourself most mornings under the same conditions and look at the weekly average or trend, not single readings. See reading your weight trend for why.
3. If your trend is flat, that intake is roughly your maintenance.
4. If you are steadily losing, your true maintenance is higher than you are eating. If you are steadily gaining, it is lower.
5. Make a small change to your daily intake, hold it for another 2 weeks, and check again.

Repeat this whenever your weight, training or daily activity changes a lot. Once you know your real maintenance, setting a cut or a lean bulk becomes simple. See cutting and bulking for sensible rates, and protein for muscle for how to split your calories.

If you have a history of disordered eating, close calorie tracking may not be helpful. Working with a dietitian or doctor is a better route than tracking numbers on your own.

Tracking it in ETS

The Body tab works out BMR and TDEE with the same formulas as the website calculator, using Katch–McArdle when you have entered a body fat figure and Mifflin–St Jeor when you have not. Your weigh-ins build a 7-day average and a trend in kg a week, so you can see whether your current intake is really maintenance and adjust your targets from there.

Sources

1. Mifflin, St Jeor and colleagues. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 1990. Abstract
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. Journal of the American Dietetic Association, 2005. Penn State record
3. Ferreira S, Marroni CA, Stein JT and colleagues. Assessment of resting energy expenditure in patients with cirrhosis (Table 1, predictive equations including McArdle). World Journal of Hepatology, 2022. Table of equations
4. FAO/WHO/UNU Expert Consultation. Human energy requirements. Food and Agriculture Organization of the United Nations, 2001. Energy requirements of adults
5. Jagim, Camic, Kisiolek and colleagues. Accuracy of resting metabolic rate prediction equations in athletes. Journal of Strength and Conditioning Research, 2018. Abstract
6. Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. Journal of the International Society of Sports Nutrition, 2014. Full text

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Last reviewed 7 October 2026. General information, not medical advice. Found a mistake? Email [email protected].