Your maintenance calories are the number of calories you burn in a full day, accounting for everything from breathing to exercise. Finding this number takes two steps: estimating your resting metabolic rate (the calories your body burns just to keep you alive), then multiplying by a factor that reflects how active you are. Most people land somewhere between 1,800 and 3,000 calories per day, but the specifics depend on your size, body composition, age, and daily movement.
Step 1: Estimate Your Resting Metabolic Rate
Your resting metabolic rate (RMR) is the energy your body uses at complete rest. It powers your heart, lungs, brain, and other organs. For most people, this accounts for 60 to 75 percent of total daily calorie burn. The most widely recommended formula for estimating it is the Mifflin-St Jeor equation, which uses your weight, height, age, and sex:
- Men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5
- Women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
If you’re working 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. A 35-year-old woman who weighs 150 pounds (68 kg) and stands 5’6″ (167.6 cm) would calculate: (10 × 68) + (6.25 × 167.6) − (5 × 35) − 161, which comes out to about 1,394 calories per day at rest.
Step 2: Factor In Your Activity Level
Your resting metabolic rate only covers what your body burns lying still. To get your total daily energy expenditure (your actual maintenance calories), multiply that number by an activity factor. The Academy of Nutrition and Dietetics uses these ranges:
- Sedentary (desk job, little exercise): multiply by 1.2 to 1.4
- Low active (light exercise 1 to 3 days per week): multiply by 1.4 to 1.6
- Active (moderate exercise 3 to 5 days per week): multiply by 1.6 to 1.9
- Very active (hard exercise 6 to 7 days, or physical job): multiply by 1.9 to 2.5
Using the example above, that 35-year-old woman with an RMR of 1,394 who exercises moderately a few days a week would multiply by roughly 1.6, landing at about 2,230 maintenance calories. This is where most people should start, then adjust based on real-world results.
The most common mistake is overestimating your activity level. If you work out four days a week but spend the rest of the day sitting, you’re closer to “low active” than “active.” Be honest with yourself here, because the gap between a 1.4 and a 1.8 multiplier on a 1,500-calorie RMR is over 600 calories per day.
A Better Formula If You Know Your Body Fat
Standard equations treat all body weight the same, but muscle tissue burns significantly more energy at rest than fat tissue does. Muscle burns roughly 5 to 7 calories per pound per day, while fat burns closer to 1 to 2 calories per pound. That difference adds up. Two people who both weigh 180 pounds can have very different metabolic rates if one carries considerably more muscle.
If you know your body fat percentage (from a DEXA scan, skinfold calipers, or a reliable smart scale), the Katch-McArdle formula gives a more personalized estimate. First, calculate your lean body mass by subtracting your fat mass from your total weight. Then plug it in:
RMR = 370 + (9.82 × lean body mass in pounds)
A 180-pound person at 20% body fat has 144 pounds of lean mass, which gives an RMR of about 1,784 calories. That same 180-pound person at 30% body fat has 126 pounds of lean mass, producing an RMR of roughly 1,607 calories. That’s a 177-calorie daily difference that standard weight-based formulas would miss entirely.
Why Formulas Are Only a Starting Point
Every formula is an estimate. Food labels themselves can be off by as much as 20%, according to FDA regulations, meaning you could be eating more calories than you think even when tracking carefully. Calorie tracking apps compound this problem because some of their entries are uploaded by users and never verified for accuracy.
The most reliable way to find your true maintenance calories is to use the formula as a starting point, eat that amount consistently for two to three weeks, and track your weight. Weigh yourself at the same time each day (morning, after using the bathroom) and look at your weekly average rather than daily fluctuations. If your average weight stays stable over two to three weeks, you’ve found your maintenance number. If you’re losing weight, add 100 to 200 calories. If you’re gaining, subtract the same.
This trial-and-error approach works because it captures variables no formula can account for: your genetics, your gut microbiome, how much you fidget, how far you walk around your office, and dozens of other small factors that influence your daily burn.
What Changes Your Maintenance Calories Over Time
Your maintenance number isn’t fixed. It shifts as your body changes. Age is the most gradual factor. You lose a small amount of muscle mass each decade after your 30s, which slowly lowers your resting metabolic rate. Staying active and doing some form of resistance training is the most effective way to counteract this.
Weight loss itself also causes a temporary dip. After losing a significant amount of weight, your metabolism can drop by roughly 50 calories per day beyond what the formulas would predict based on your new size. Research published in The American Journal of Clinical Nutrition found this “metabolic adaptation” averaged about 54 calories per day after weight loss. The encouraging finding: this effect largely disappeared within one to two years, suggesting it’s a temporary adjustment rather than a permanent metabolic slowdown.
What you eat matters too, not just how much. Digesting food itself burns calories, a process called the thermic effect of food. Protein costs your body the most to process, burning 15 to 30 percent of its calories during digestion. Carbohydrates burn 5 to 10 percent, and fats just 0 to 3 percent. This means a high-protein diet at the same calorie level leaves slightly fewer net calories available compared to a high-fat diet. It’s not a dramatic difference, but over weeks and months it adds up, and it’s one reason higher-protein diets tend to make maintenance easier.
Putting It All Together
Start with the Mifflin-St Jeor formula (or Katch-McArdle if you know your body fat percentage). Multiply by an honest activity factor. Eat at that calorie level for two to three weeks while weighing yourself daily and averaging weekly. Adjust by 100 to 200 calories based on what the scale does. Once your weight holds steady, that’s your maintenance number.
Revisit the calculation every time something significant changes: you gain or lose more than 10 pounds, your exercise routine shifts dramatically, or you age into a new decade. Your maintenance calories are a moving target, but once you understand the process, recalibrating takes minutes.