For most adults, maintenance calories fall somewhere between 1,600 and 3,000 per day, depending on your size, age, sex, and how active you are. General guidelines suggest roughly 2,500 calories for an average man and 2,000 for an average woman, but these are broad estimates. Your actual number could be several hundred calories higher or lower.
The good news is that you can get a reasonably accurate estimate with a simple two-step process: calculate your basal metabolic rate (the calories your body burns just to stay alive), then multiply it by a factor that reflects how much you move throughout the day.
How to Calculate Your Number
The most widely recommended formula is the Mifflin-St Jeor equation. It uses your weight, height, age, and sex to estimate your basal metabolic rate (BMR):
- 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, multiply your weight in pounds by 0.453 to get kilograms, and your height in inches by 2.54 to get centimeters.
As a quick example: a 35-year-old woman who is 5’6″ (167.6 cm) and weighs 150 lbs (68 kg) would get a BMR of about 1,387 calories. A 35-year-old man at 5’10” (177.8 cm) and 180 lbs (81.6 kg) would get roughly 1,757 calories. That’s just the energy needed to keep your organs running, your lungs breathing, and your heart beating while you lie completely still.
Adjusting for Activity Level
Your BMR only accounts for the calories your body uses at rest. To find your actual maintenance calories, multiply your BMR by one of these activity factors:
- Sedentary (desk job, little to no exercise): BMR × 1.2
- Lightly active (light exercise 1–3 days per week): BMR × 1.375
- Moderately active (moderate exercise 3–5 days per week): BMR × 1.55
- Very active (heavy exercise 6–7 days per week): BMR × 1.725
- Extremely active (intense training twice daily or hard physical labor): BMR × 1.9
Returning to our example, the 35-year-old woman with a BMR of 1,387 who exercises moderately three to five days a week would multiply by 1.55, landing at roughly 2,150 maintenance calories. If she were sedentary, that number drops to about 1,664. The difference between activity levels is substantial, often 400 to 700 calories per day.
Most people overestimate their activity level. If you work a desk job and hit the gym three times a week for 45 minutes, “lightly active” is probably more accurate than “moderately active.” Be honest with yourself here, because choosing the wrong multiplier can throw your estimate off by hundreds of calories.
Why Body Composition Matters
The Mifflin-St Jeor equation doesn’t account for how much of your weight is muscle versus fat. Two people who weigh the same can have very different metabolic rates. Muscle tissue burns roughly 4.5 to 7 calories per pound per day at rest, while fat tissue burns far less, about 50 to 100 times less per equivalent weight.
If you know your body fat percentage (from a DEXA scan, smart scale, or even a rough visual estimate), you can use the Katch-McArdle formula instead. First, calculate your lean body mass: take your total weight in kilograms and subtract your fat mass (total weight × body fat percentage). Then plug it in: BMR = 370 + (21.6 × lean body mass in kg). This formula is particularly useful for people who carry significantly more or less muscle than average, like athletes or people who have been strength training for years.
What Makes Your Number Change Over Time
Your maintenance calories aren’t fixed. They shift as your body, habits, and age change.
Age
A large 2021 study upended the old assumption that metabolism tanks in your 30s and 40s. Researchers found that both total energy expenditure and basal metabolic rate remain largely stable from age 20 through about 60, regardless of sex. The real decline starts around age 60, at a rate of about 0.7% per year. By age 90, total energy expenditure is roughly 26% lower than in middle age. So if you’re in your 30s or 40s and gaining weight, the culprit is more likely changes in activity or eating habits than a slowing metabolism.
Dieting History
When you eat in a calorie deficit, your body adapts by burning less energy than the math would predict. This phenomenon, called adaptive thermogenesis, kicks in quickly. Research measuring subjects in metabolic chambers found that after just one week of calorie restriction, energy expenditure dropped by an average of 178 calories per day beyond what could be explained by lost body mass. That adaptation tends to persist during and even after the diet ends. This is one reason people who have dieted extensively often find that their actual maintenance calories are lower than any calculator predicts.
Daily Movement Outside the Gym
One of the most underappreciated factors is non-exercise activity thermogenesis, or NEAT. This includes everything from fidgeting and pacing to walking around the office, cooking, and even standing instead of sitting. According to research from the Mayo Clinic, NEAT can vary by up to 2,000 calories per day between two people of similar size. That’s an enormous range and helps explain why some people seem to eat freely without gaining weight. If you switched from an active job to a desk job, or started working from home, your maintenance calories may have dropped significantly even if your gym routine stayed the same.
What You Eat
Your body uses energy to digest food, and the amount varies dramatically by macronutrient. Protein costs the most to process, increasing your metabolic rate by 15 to 30% of the protein calories consumed. Carbohydrates increase it by 5 to 10%, and fats by just 0 to 3%. This means that shifting toward a higher-protein diet can modestly raise your total daily energy expenditure without changing how much you eat overall. It’s not a massive effect, but over weeks and months it adds up.
How to Verify Your Estimate
No formula is perfect. They’re estimates based on population averages, and individual variation is real. The best way to find your true maintenance calories is to track what you eat and what your weight does over two to three weeks. Pick a calorie target from the formula, eat consistently at that level, and weigh yourself daily at the same time (morning, after using the bathroom). Look at the weekly average, not daily fluctuations.
If your average weight stays stable over two to three weeks, you’ve found your maintenance range. If you’re slowly gaining, your maintenance is a bit lower. If you’re losing, it’s higher. Adjust by 100 to 200 calories and re-evaluate. This real-world testing will always be more accurate than any equation, because it captures everything the formulas miss: your genetics, your NEAT, your dieting history, and the specific way your body processes food.
For most people, the formula gets you within 200 to 300 calories of your true number. That’s close enough to start, and a few weeks of tracking will dial it in the rest of the way.