Your maintenance calories are the total number of calories your body burns in a day, and for most adults that falls somewhere between 1,600 and 3,000. The exact number depends on your weight, height, age, sex, and how active you are. You can get a solid estimate using a simple formula and an activity multiplier, though the real number can shift based on factors most calorie calculators ignore entirely.
How to Estimate Your Baseline
The most reliable starting point is the Mifflin-St Jeor equation, which estimates your resting metabolic rate, the calories your body burns just keeping you alive (breathing, circulating blood, maintaining body temperature). A systematic review in the Journal of the American Dietetic Association found this formula predicted resting metabolism within 10% of the actual measured value more often than any other equation tested, in both normal-weight and obese individuals.
The formula works like this:
- 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
To convert your weight, divide pounds by 2.2. To convert your height, multiply inches by 2.54. 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 = roughly 1,394 calories per day at rest. That’s before any physical activity is factored in.
Adding Your Activity Level
Your resting metabolic rate only accounts for what your body burns lying still. To get your actual maintenance calories, you multiply that number by an activity factor. The Food and Agriculture Organization of the United Nations uses these ranges:
- Sedentary or lightly active (desk job, minimal exercise): multiply by 1.4 to 1.69
- Moderately active (regular exercise or physical job): multiply by 1.7 to 1.99
- Vigorously active (intense daily training or heavy labor): multiply by 2.0 to 2.4
Using the example above, that 35-year-old woman with a resting rate of 1,394 calories who works a desk job and exercises a few times a week might use a multiplier of 1.55, putting her maintenance around 2,160 calories per day. Someone with the same stats who trains hard six days a week could land closer to 2,800. Activity level values above 2.4 are difficult to sustain long-term, even for athletes.
Why Your Real Number May Differ
Even the best formula is an estimate. A 10% margin of error on a 2,000-calorie estimate means your true maintenance could be anywhere from 1,800 to 2,200. Several factors create that gap.
The biggest wildcard is something called non-exercise activity thermogenesis: the calories you burn fidgeting, standing, walking to the kitchen, gesturing while you talk, even maintaining posture. Research from the Mayo Clinic found that this type of unconscious movement can vary by up to 2,000 calories per day between two people of similar size. That’s an enormous range, and no calculator accounts for it. If you’re naturally restless and on your feet a lot, your maintenance is higher than someone with the same stats who sits still most of the day.
Your body composition matters too. A pound of muscle burns roughly 4.5 to 7 calories per day at rest, while fat tissue burns far less. Two people who weigh the same but carry different ratios of muscle to fat will have different resting metabolic rates, and the standard formulas can’t distinguish between them.
What you eat also plays a small role. Your body spends energy digesting and processing food. Protein costs the most, using 15 to 30% of its own calories just to be digested. Carbohydrates use 5 to 10%, and fats use almost nothing at 0 to 3%. A high-protein diet nudges your total daily burn slightly higher compared to a diet heavy in fats, even if the total calorie count is identical.
What Happens After Weight Loss
If you’ve recently lost a significant amount of weight, your maintenance calories will be lower than the formula predicts. This goes beyond the obvious fact that a lighter body needs less fuel. After weight loss, your metabolism dips more steeply than the numbers on paper would suggest. Researchers at UAB illustrated this with an example: a person who drops from 220 to 198 pounds might expect their needs to fall from 2,500 to around 2,200 calories, but measured energy expenditure could land closer to 2,000.
The encouraging finding is that this extra dip appears to be temporary. When researchers gave participants a month after weight loss for their bodies to stabilize, the gap shrank to just a few dozen calories per day. Part of the initial drop comes from the fact that weight loss actually reduces the size of several internal organs, including the heart, pancreas, and kidneys, and organs burn energy at a rate up to 20 times higher than muscle tissue. As the body adjusts, much of that effect fades. And importantly, the size of this metabolic dip does not predict whether someone will regain the weight over the following two years.
How to Find Your Actual Number
The formula gives you a starting point. Finding your true maintenance calories takes about two to four weeks of real-world tracking. Pick a calorie target based on your calculation, eat consistently at that level, and weigh yourself daily at the same time (first thing in the morning works best). Look at the weekly average, not day-to-day fluctuations. If your average weight stays flat over two to three weeks, you’ve found your maintenance. If you’re slowly gaining, drop by 100 to 150 calories. If you’re losing, add the same amount.
This approach works because it captures all the variables no formula can: your genetics, your gut microbiome, your fidgeting habits, your job, your sleep quality. The math gets you in the neighborhood. Consistent tracking gets you to the actual address.