Calorie Calculator

About the Calorie Calculator

Your body burns energy all day, even if you never leave the couch. Breathing, circulating blood, maintaining temperature, and repairing tissue make up your basal metabolic rate, usually written BMR. On top of that comes everything you do: walking to the car, chasing a toddler, lifting weights, even fidgeting. Add the two together and you have your total daily energy expenditure, or TDEE, which is the number of calories you can eat on an average day and stay at the same weight. This calculator estimates both from your sex, age, height, weight, and typical activity.

Under the hood it uses the Mifflin-St Jeor equation, published in 1990, to estimate BMR, then multiplies by an activity factor that runs from 1.2 for a mostly sedentary routine up to 1.9 for hard training every day. From the maintenance figure, it also lists three practical targets: a 10 percent deficit for mild weight loss, a 20 percent deficit for faster loss, and a 15 percent surplus for weight gain. Seeing them side by side makes it easier to pick a pace that matches your goal and your lifestyle.

Treat every output as an educated starting point. The equation only knows four facts about you, and it cannot see your muscle mass, genetics, medications, sleep, or how accurately you judge your own activity. The sensible way to use it is to eat near the figure for a few weeks while tracking your weight, then adjust up or down based on what the scale and your energy levels tell you. The calculator gives you the first guess, and your own data refines it.

When to Use It

How to Use It, Step by Step

1. Select your Sex as Male or Female. The equation has a different constant for each, reflecting average differences in body composition between the sexes, so choose the option that best describes your body.
2. Enter your Age in years. The calculator accepts ages from 15 to 100, and each added year lowers the estimated BMR slightly, so use your current age.
3. Pick U.S. or Metric with the unit toggle, then enter Height. In U.S. mode, type feet and inches in two boxes. In Metric mode, enter centimeters.
4. Enter your current Weight in pounds or kilograms. Use a recent morning reading instead of an old number, because a 20-pound change moves the result by a couple hundred calories.
5. Choose your Activity level from the dropdown: sedentary, light, moderate, active, or very active. Base it on your typical week including exercise and daily movement, not your best week.
6. Select Calculate Calorie Needs and read the results. BMR is what you would burn at rest, TDEE is your estimated maintenance level, and the three lines beneath are weight-loss and weight-gain targets.
7. Pick the target that matches your goal. Mild loss at minus 10 percent is a gentle starting point, while minus 20 percent is faster and harder to sustain. The plus 15 percent line is the weight-gain option.
8. Follow the plan for two to four weeks while tracking your weight, then compare the trend with what you expected and adjust your intake by 100 to 200 calories if you are not moving in the right direction.

Understanding Your Results

BMR is the energy needed to keep you alive at complete rest, and it typically makes up the biggest share of what you burn. It is not a target to eat at. Your maintenance figure, labeled TDEE, is BMR multiplied by the activity factor you chose and is the number to compare with your current eating. If your weight has been stable and your logged intake is far from this estimate, the likely explanation is that the activity level chosen is off, or that logging is incomplete.

The three target lines are simple percentages of TDEE. A 10 percent deficit on a 2,000-calorie maintenance is 1,800, a 20 percent deficit is 1,600, and a 15 percent surplus is 2,300. Smaller changes are easier to maintain and less likely to cost muscle or energy, which is why many people start with the milder option. A bigger deficit speeds up loss in the short term, but hunger, fatigue, and rebound eating can make it harder to stick with.

To check the estimate, compare it with real-world results. Weigh yourself regularly and track your average intake over two to four weeks. If your weight stays steady, your true maintenance is close to what you ate. If it drifts, adjust by a modest amount. Remember that maintenance changes as your weight does, so recalculate after a meaningful change, and consult a registered dietitian or physician if you have a medical condition or are pregnant.

More Worked Examples

Tips for Better Results

• If you are between two activity levels, choose the lower one. Most people overestimate how active they are, and eating to an inflated maintenance figure is a common reason for weight loss stalling.
• Weigh yourself several times per week and look at the weekly average. Daily weight can move by several pounds from water and food volume, so the trend line is much more informative than any single morning.
• Give a new calorie target at least two to three weeks before judging it. Early changes on the scale are often water, and a longer window shows whether your estimated maintenance is accurate.
• Protein and resistance training help preserve muscle while eating in a deficit. Even a modest deficit works better when you keep lifting or doing bodyweight exercises regularly.
• Recalculate after losing or gaining around 10 to 15 pounds, because a lighter body needs fewer calories, and your earlier targets will no longer fit the same way.
• Log your food honestly for a week before changing anything. Comparing a real average with the estimated maintenance figure tells you more than any formula and often reveals where the gap is.

Common Mistakes to Avoid

• Eating at the BMR figure to lose weight faster. BMR is only the energy for resting functions, and it ignores all movement, so eating that low is too aggressive for most people and difficult to sustain.
• Counting exercise twice. The activity multiplier already includes your workouts, so do not add the calories burned by exercise (from a watch or machine) on top of the TDEE figure.
• Choosing the very active level because of a hard workout once or twice a week. That setting is meant for hard training most days, and using it inflates your calorie estimate by hundreds of calories.
• Treating the numbers as exact. Individual metabolism varies, and the estimate can be off by a few hundred calories in either direction, so use it as a starting point and adjust from results.
• Applying the adult equation to a growing teenager, a pregnant or breastfeeding person, or someone with a medical condition. Their needs differ, so work with a clinician or dietitian for these situations.

Assumptions and Limits

• The Mifflin-St Jeor equation was derived from measurements of adults, using only weight, height, age, and sex. It does not account for muscle mass, body fat percentage, hormones, or medical conditions, and it can miss by a few hundred calories.
• Activity multipliers are broad averages. Your job, your daily step count, and your training intensity all affect real expenditure, and the labels in the dropdown are approximations of how different people describe their routines.
• The weight-loss and gain lines are straightforward percentages of the maintenance estimate, not clinical prescriptions. Real-world weight change also depends on water, hormones, sleep, and adaptation, so progress will not be perfectly linear.
• Very low calorie intakes, rapid weight loss, and plans for people under 18, older adults with health issues, or anyone who is pregnant should be supervised by a physician or registered dietitian.

Key Terms

Basal metabolic rate (BMR)

The number of calories your body burns at complete rest to keep basic functions such as breathing, circulation, and temperature regulation running.

Total daily energy expenditure (TDEE)

Your estimated total calorie burn in a day, combining BMR with the energy used for movement, exercise, and digesting food. It represents maintenance.

Activity factor

A multiplier applied to BMR to account for how active you are, ranging from 1.2 for sedentary lifestyles to 1.9 for very hard daily training.

Calorie deficit

Eating fewer calories than you burn, which forces the body to draw on stored energy and, over time, leads to weight loss.

Calorie surplus

Eating more calories than you burn, which provides the extra energy needed to gain weight, including muscle when combined with strength training.

Mifflin-St Jeor equation

A formula published in 1990 that estimates BMR from weight, height, age, and sex, and which is widely used because it performs well for modern adults.