Your maintenance calories are the number of calories you burn in a full day, including everything from breathing to exercising. To calculate them, you find your basal metabolic rate (the calories your body burns at rest) and then multiply it by a number that reflects how active you are. For most people, this takes about two minutes with a calculator.
Step 1: Find Your Basal Metabolic Rate
The most widely recommended formula is the Mifflin-St Jeor equation. It uses your weight, height, age, and sex to estimate how many calories your body burns just to keep you alive, before any movement or exercise.
For men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5
For women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
If you think in pounds and inches, convert first. Divide your weight in pounds by 2.2 to get kilograms, and multiply your height in inches by 2.54 to get centimeters.
As a quick example: a 35-year-old man who weighs 180 pounds (81.8 kg) and stands 5’10” (177.8 cm) would calculate (10 × 81.8) + (6.25 × 177.8) − (5 × 35) + 5, which comes out to about 1,754 calories per day at rest.
Step 2: Multiply by Your Activity Level
Your basal metabolic rate only covers the energy cost of lying in bed all day. To get your actual maintenance calories (often called total daily energy expenditure, or TDEE), multiply your BMR by an activity factor. The standard multipliers range from 1.2 to 1.9:
- Sedentary (1.2): Desk job, little or no intentional exercise
- Lightly active (1.375): Light exercise or walking a few days per week
- Moderately active (1.55): Moderate exercise 3 to 5 days per week
- Very active (1.725): Hard training 6 to 7 days per week
- Extremely active (1.9): Physically demanding job plus daily intense training
Using the example above, that 35-year-old man with a BMR of 1,754 who exercises moderately would multiply 1,754 × 1.55, giving him an estimated maintenance intake of roughly 2,719 calories per day.
Choosing the Right Activity Level
This is where most people go wrong. The single biggest source of error in the entire calculation is overestimating how active you are. If you work out three times a week but spend the rest of your day sitting, “lightly active” is more honest than “moderately active.”
Daily step count is a useful reality check. Fewer than 5,000 steps a day is sedentary. Between 5,000 and 7,500 is semi-active. The 7,500 to 10,000 range is somewhat active, and you generally need 10,000 or more steps to qualify as truly active. These numbers count all your steps, not just exercise, so they capture the kind of low-grade movement that multipliers are trying to account for.
When in doubt, start with a lower multiplier. It’s much easier to add 100 to 200 calories later than to spend weeks wondering why you’re gaining weight on a “maintenance” number that was too generous from the start.
An Alternative Formula if You Know Your Body Fat
The Mifflin-St Jeor equation treats all weight the same, whether it’s muscle or fat. If you know your body fat percentage (from a DEXA scan, calipers, or even an estimate), the Katch-McArdle formula can be more accurate because it bases the calculation on lean body mass alone.
First, calculate your lean body mass: total weight minus (total weight × body fat percentage). So a 180-pound person at 20% body fat has 144 pounds of lean mass.
Then plug it in: BMR = 370 + (9.82 × lean body mass in pounds). For the example above, that’s 370 + (9.82 × 144) = roughly 1,784 calories at rest. You then multiply by the same activity factors listed above.
This formula is especially useful for people at the extremes of body composition. Someone who carries significantly more muscle than average will get a higher (and more accurate) result from Katch-McArdle than from Mifflin-St Jeor. The reverse is true for someone with a higher body fat percentage, where Mifflin-St Jeor may overestimate needs.
What the Formulas Don’t Capture
Every formula gives you an estimate, not a precise number. Several real-world factors shift your actual maintenance calories in ways no equation can fully account for.
The thermic effect of food is one. Your body burns calories just digesting what you eat. Protein costs the most to process, increasing your metabolic rate by 15 to 30% of the calories in that protein. Carbohydrates cost 5 to 10%, and fats cost 0 to 3%. This means two people eating the same total calories but different ratios of protein to fat will burn slightly different amounts through digestion alone. This doesn’t mean you need to adjust your formula, but it does explain why higher-protein diets tend to make maintenance slightly easier.
Other factors include genetics, sleep quality, stress hormones, and how much you fidget and move unconsciously throughout the day (called non-exercise activity thermogenesis). Two people with identical stats on paper can have maintenance calories that differ by a few hundred calories. The formula gets you in the right neighborhood. Your real-world results tell you the exact address.
How to Verify Your Number
Treat your calculated maintenance calories as a starting point, not a final answer. Eat at that number consistently for two to three weeks while weighing yourself daily at the same time (first thing in the morning works best). Track the weekly average, not day-to-day fluctuations, since water weight can swing a pound or two in either direction overnight.
If your average weight stays stable over two to three weeks, you’ve found your maintenance. If you’re slowly gaining, drop by 100 to 150 calories and repeat. If you’re slowly losing, add the same amount. This feedback loop is more reliable than any formula because it accounts for all the individual variables that equations miss.
Keep in mind that your maintenance calories aren’t fixed. They shift as your weight changes, as you age, as your activity patterns change, and even across seasons. Recalculating every few months, or whenever your routine changes significantly, keeps the number useful.