Daily Calorie Calculator

How Many Calories Should I Eat Per Day? Start Here

Calorie needs are deeply personal. Two people who appear similar on the surface—same height, same weight, same age—can have noticeably different daily energy requirements depending on their muscle mass, hormone levels, metabolic health, and especially how active they are throughout the day. Generic advice like "eat 2,000 calories a day" works fine as a rough population average, but it's rarely accurate enough to actually drive meaningful results for any specific individual trying to manage their weight or fuel their training.

Our free daily calorie calculator takes the guesswork out of this process by using the Mifflin-St Jeor equation, which is the most widely validated formula for estimating Basal Metabolic Rate (BMR) in adults. Once your BMR is established, the tool multiplies it by an activity factor based on how you described your lifestyle—from completely sedentary to highly active athlete—to produce your Total Daily Energy Expenditure (TDEE). This is the number that actually matters for weight management: the estimated total calories your body burns in an average day given your current lifestyle and activity level.

Understanding BMR and TDEE: The Two Numbers That Drive Everything

Before you can do anything useful with calorie targets, it helps to understand what these two foundational metrics actually represent and how they differ from each other.

Your Basal Metabolic Rate (BMR) is the number of calories your body would burn if you did absolutely nothing all day. No movement, no exercise, no conscious activity—just lying completely still in a temperature-controlled room. Your body still needs energy to maintain its core temperature, keep your heart beating, support brain function, power your digestive system, and sustain every other involuntary biological process that keeps you alive. BMR represents the caloric cost of all of that baseline biological maintenance. For most adults, BMR accounts for roughly 60 to 75 percent of total daily calorie expenditure.

Your Total Daily Energy Expenditure (TDEE) is your BMR scaled up to account for the calories you burn through physical activity and the thermic effect of food—the energy your body uses to digest and process what you eat. This is the number our calorie intake calculator ultimately gives you, and it's the figure you need to know when setting a target for weight loss, weight gain, or maintenance.

The Mifflin-St Jeor Formula Explained

Our calculator uses the Mifflin-St Jeor equation, published in the Journal of the American Dietetic Association and since adopted as the standard formula recommended by most registered dietitians for estimating BMR. It offers a meaningful improvement in accuracy over the older Harris-Benedict equation by better accounting for real-world body composition differences.

For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5

For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

Once BMR is calculated, it's multiplied by an activity multiplier to produce TDEE. The activity levels used in our tool correspond to well-established multipliers: Sedentary (desk job, little or no exercise) uses 1.2; Light exercise one to three days per week uses 1.375; Moderate exercise three to five days per week uses 1.55; Heavy exercise six to seven days per week uses 1.725; and athletes training twice daily use 1.9.

Selecting the right activity level is arguably the most important input in the entire calculation. Many people underestimate their activity and choose "sedentary" when they actually walk a significant distance each day and engage in light physical tasks regularly. Others overestimate and select "heavy exercise" when they train three times per week at moderate intensity. Be honest with yourself here—the output is only as useful as the accuracy of your inputs.

How to Use Your TDEE for Weight Loss, Gain, or Maintenance

Once you have your TDEE, applying it to weight management is fairly direct. Body weight change is primarily driven by the relationship between how many calories you consume and how many you burn. A sustained calorie deficit leads to weight loss; a sustained surplus leads to weight gain; matching your TDEE closely results in maintenance.

Creating a Calorie Deficit for Weight Loss

To lose weight, you need to consistently consume fewer calories than your TDEE. A deficit of approximately 500 calories per day is commonly associated with losing roughly one pound (0.45 kg) of body weight per week, based on the estimate that one pound of fat stores approximately 3,500 calories. In practice, weight loss is never perfectly linear—water retention, hormonal fluctuations, and changes in muscle mass all create variability—but a moderate deficit applied consistently over time does produce meaningful fat loss.

Aggressive calorie restriction—cutting more than 1,000 calories per day below your TDEE—can be counterproductive over the long term. It often triggers compensatory hunger, reduces energy available for physical activity, promotes muscle loss alongside fat loss, and gradually slows the metabolic rate as the body adapts to scarcity. Most nutrition professionals recommend targeting a deficit in the 300–500 calorie range as a more sustainable approach that preserves muscle and maintains energy levels.

Building a Calorie Surplus for Muscle Gain

For individuals focused on building lean muscle mass, consuming slightly more calories than TDEE provides the energy substrate needed for muscle protein synthesis and recovery from resistance training. A modest surplus of 200–350 calories per day, paired with a consistent strength training program and sufficient protein intake, supports muscle growth while minimizing unnecessary fat accumulation. Larger surpluses—sometimes called "dirty bulking"—do accelerate weight gain but typically result in a less favorable ratio of muscle to fat gained over time.

Eating at Maintenance

Maintenance eating—consuming approximately your TDEE—is appropriate when you're satisfied with your current body composition and simply want to sustain it. It's also recommended during planned diet breaks, which are intentional periods of eating at maintenance inserted between prolonged calorie-deficit phases. These breaks help reset hunger hormones, restore training performance, and maintain a healthier psychological relationship with food before returning to a deficit.

Important Limitations to Keep in Mind

Formula-based calorie calculators are powerful starting points, but they produce estimates rather than exact values. Individual metabolism varies more than most people realize. Factors like gut microbiome composition, thyroid function, medication use, sleep quality, and chronic stress all influence actual calorie expenditure in ways that no equation can precisely account for.

The most reliable approach is to use the calculator's output as a starting target, track your actual food intake alongside your weight for two to three weeks, and then adjust your calorie target up or down based on how your weight actually responds. If you're eating at your calculated TDEE but still losing weight, your actual maintenance calories are likely higher than the estimate. If you're gaining weight at TDEE, they're lower.

Also note that this calculator is designed for adults and is not appropriate for use with children, teenagers, pregnant or breastfeeding women, or individuals with medical conditions affecting metabolism. For those populations, working directly with a registered dietitian or physician is the appropriate path.

Your Health Data Stays Completely Private

Health information like your weight, height, age, and gender is genuinely sensitive personal data. Our calculator is built on a privacy-first architecture: every calculation runs entirely within your browser using JavaScript, and none of your inputs are transmitted to any server or stored in any database. There's no account to create, no email to provide, and no data to share with anyone. The information you enter exists only in your browser tab, and it disappears permanently the moment you close or navigate away from the page. You get the precision of a clinical nutrition tool without surrendering any personal information to get it.