Your maintenance calories are the number of calories you burn in a full day when you’re neither gaining nor losing weight. For most adults, this falls somewhere between 1,800 and 3,000 calories per day, depending on body size, muscle mass, age, sex, and how active you are. There are two reliable ways to find your number: calculate an estimate using a formula, or track your intake and weight over time and let the real-world data tell you.
Start With Your Resting Metabolic Rate
Your body burns the majority of its daily calories just keeping you alive. Breathing, circulating blood, maintaining body temperature, and running your brain all require energy, even if you spend the entire day on a couch. This baseline burn is called your resting metabolic rate (RMR), and it typically accounts for 60 to 70% of the total calories you use each day.
The most widely recommended formula for estimating RMR is the Mifflin-St Jeor equation. A systematic review in the Journal of the American Dietetic Association found it was the most reliable option tested, predicting resting metabolic rate within 10% of the actual measured value more often than competing formulas. Here’s how it works:
- 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 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. A 35-year-old woman who weighs 150 pounds (68 kg) and stands 5’6″ (168 cm) would calculate: (10 × 68) + (6.25 × 168) − (5 × 35) − 161, which comes out to about 1,394 calories per day at rest.
Why Body Composition Changes the Math
Standard formulas use total body weight, but not all weight is created equal. Muscle tissue is far more metabolically active than fat tissue, meaning two people who weigh the same can have meaningfully different resting metabolic rates if one carries more muscle. A 180-pound person with 15% body fat burns more at rest than a 180-pound person with 30% body fat.
If you know your body fat percentage (from a DEXA scan, skinfold calipers, or even a rough estimate), you can use the Katch-McArdle formula instead. It’s built around lean body mass rather than total weight: RMR = 370 + (21.6 × lean mass in kg). To find your lean mass, subtract your fat mass from your total weight. For example, a 180-pound person at 20% body fat has 144 pounds of lean mass, or about 65.5 kg. That gives an RMR of roughly 1,785 calories. This approach is especially useful if you’re notably muscular or carry more body fat than average, since those are the situations where standard weight-based formulas tend to miss the mark.
Factor In Your Activity Level
Once you have an RMR estimate, you need to account for everything you do beyond resting: walking, working, exercising, even fidgeting. The simplest method is to multiply your RMR by a physical activity level (PAL) factor. The Food and Agriculture Organization of the United Nations categorizes these into three tiers:
- Sedentary or lightly active (PAL 1.4 to 1.69): Desk job, minimal intentional exercise. Most of your day is spent sitting or standing with light movement.
- Moderately active (PAL 1.7 to 1.99): Regular exercise several times per week, or a job that keeps you on your feet and moving for much of the day.
- Vigorously active (PAL 2.0 to 2.4): Intense daily training, manual labor, or a combination of both. Values above 2.4 are difficult to sustain over the long term.
Using the earlier example of the woman with a 1,394-calorie RMR: if she exercises moderately a few times per week but otherwise has a desk job, a multiplier around 1.55 puts her maintenance estimate near 2,160 calories. If she’s training hard five or six days a week plus walking throughout the day, a multiplier of 1.8 would bring her to roughly 2,510.
Choosing the right multiplier is the trickiest part. Most people overestimate their activity level. If you’re unsure, start with the lower end of the range that feels appropriate. You can always adjust upward once you see how your body responds.
The Role of What You Eat
Your body spends energy just digesting and processing food. This is called the thermic effect of food, and it adds a smaller but real layer to your daily calorie burn. Not all macronutrients cost the same amount of energy to process. Protein has the highest thermic effect, using up 15 to 30% of its own calories during digestion. Carbohydrates use 5 to 10%, and fats use 0 to 3%.
In practical terms, this means a higher-protein diet slightly increases your total daily expenditure compared to a diet with the same number of calories but more fat. The difference isn’t dramatic enough to override a calorie surplus, but it does explain why protein-rich diets can have a small metabolic advantage. Most formulas already assume an average mixed diet, so you don’t need to calculate this separately. Just know that if your diet shifts heavily toward one macronutrient, your real maintenance number could nudge up or down by 50 to 100 calories.
Test Your Estimate With Real Data
Formulas give you a starting point, not a final answer. The most accurate way to find your maintenance calories is to track what you actually eat and what your weight actually does over two to three weeks. Here’s a simple process:
Pick your calculated estimate and eat that amount consistently for 14 days. Weigh yourself every morning under the same conditions (after using the bathroom, before eating) and track the trend. Daily fluctuations of one to three pounds are normal, driven by water retention, sodium intake, and digestion. What matters is the average direction over two weeks. If your weight trend is flat, you’ve found your maintenance. If you’re losing about half a pound per week, add roughly 250 calories. If you’re gaining, subtract a similar amount. Repeat for another two weeks and reassess.
This method takes patience, but it accounts for all the individual variables that no formula can capture: your genetics, your non-exercise movement habits, your gut microbiome, and your hormonal profile. It also catches something important that calculators miss entirely.
Metabolic Adaptation After Dieting
If you’ve recently lost weight through calorie restriction, your maintenance calories are likely lower than any formula would predict. Your body responds to sustained energy deficits by reducing its energy expenditure beyond what the loss of body mass alone would explain. Research on overweight adults found that this adaptive drop averaged about 178 calories per day after just one week of calorie restriction, and it remained relatively stable throughout and even after the dieting period.
This matters because someone who has dieted down to 160 pounds will often burn fewer calories at rest than someone who has been 160 pounds their whole life. The gap can persist for months or longer. It’s one of the main reasons weight regain is so common, and it’s also why the tracking method described above is so valuable. Formulas can’t see this adaptation. Your scale can.
The practical takeaway: if you’re transitioning from a calorie deficit to maintenance, increase calories gradually over two to four weeks rather than jumping straight to a calculated number. This gives your metabolism time to adjust upward and helps you identify your true new maintenance level without overshooting into a surplus.
Putting It All Together
Calculate your RMR with the Mifflin-St Jeor equation (or Katch-McArdle if you know your body fat percentage). Multiply by an honest activity factor. Use that number as a starting point. Then spend two to three weeks tracking intake and morning weight to see whether reality matches the math. Adjust in increments of 100 to 250 calories based on what your weight trend tells you, and expect to revisit the number as your body, activity, or age changes. Maintenance calories aren’t a fixed target. They shift with your life, and checking in every few months keeps your estimate useful.