Calorie Calculator

Take a 30-year-old man who is 5'10" and 180 lb and exercises a few days a week (moderately active). His resting burn (BMR) works out to about 1,783 calories, and once you factor in his activity, his maintenance level (TDEE) is roughly 2,763 calories per day. To lose about a pound a week he'd aim for around 2,263 calories; to gain a pound a week, about 3,263 calories. That single maintenance number is the anchor for every goal, which is why this calorie calculator shows it first and then builds loss and gain targets around it.

How daily calories are calculated

We use the Mifflin-St Jeor equation to estimate basal metabolic rate (BMR) - the calories you burn at complete rest - then multiply by an activity factor. If you only want the resting figure, the BMR Calculator isolates it; the TDEE Calculator focuses on the maintenance total. The formulas:

Imperial entries (pounds and feet/inches) are converted to kilograms and centimeters before the formula runs, so US and metric users get identical results. The activity factors are 1.2 (sedentary), 1.375 (lightly active), 1.55 (moderately active), 1.725 (very active) and 1.9 (extra active).

Calories for weight loss and weight gain

Body weight follows energy balance: eat fewer calories than you burn and you lose weight; eat more and you gain. Because a pound of fat stores roughly 3,500 calories, a daily deficit of 500 calories targets about 1 pound of loss per week, and 250 calories targets about half a pound. The same math in reverse - a 500-calorie surplus - supports roughly a pound of gain per week, ideally paired with strength training so more of it is muscle. Real-world results vary because metabolism adapts and water weight fluctuates, so weigh the trend over weeks, not days.

Choosing the right activity level

Picking your activity level honestly matters more than any other input. Most people overestimate it: a desk job with a couple of gym sessions is usually lightly or moderately active, not "very active." Your activity factor already includes your workouts, so you don't need to add exercise calories on top. If your weight isn't moving after 2-4 weeks, that's the signal to nudge your target or re-check the level you chose.

Eat enough - and eat well

Calories are only half the picture. Within your target, prioritize adequate protein, plenty of vegetables and fiber, and minimally processed foods to stay full and protect muscle. Once you know your calorie number, the Macro Calculator splits it into protein, carbohydrate and fat grams so you can build meals around it. Avoid extreme deficits: dropping below about 1,500 calories/day for men or 1,200/day for women without supervision can backfire through fatigue, muscle loss and rebound eating. For tailored advice, talk to a registered dietitian.

How to use this calculator

You only need five pieces of information to get a realistic estimate. Work through the inputs in order:

1. Sex: the Mifflin-St Jeor formula uses a different constant for men and women, so this changes your result by roughly 150-200 calories.
2. Age: resting metabolism falls gradually with age, so an older person needs fewer calories than a younger one at the same size.
3. Height and weight: enter them in US units (feet/inches and pounds) or switch to metric (cm and kg). The calculator converts imperial values internally, so both give the same answer.
4. Activity level: choose the option that best matches a typical week, including any regular exercise. This is the input people get wrong most often - when unsure, pick the lower level.

The result updates instantly. Read your maintenance (TDEE) number first, then use the loss and gain targets shown beneath it as starting points for your goal.

A second worked example: weight loss for a woman

Consider a 40-year-old woman who is 5'4" (163 cm) and 160 lb (72.6 kg) and is lightly active. Her BMR works out to about 1,381 calories. Multiplying by the lightly active factor of 1.375 gives a maintenance level of roughly 1,899 calories per day. To lose about a pound a week she would aim for around 1,399 calories - close to the recommended floor for women, so a gentler 250-calorie deficit (about 1,649 calories, losing half a pound a week) is usually more sustainable. This is exactly why the calculator shows a mild loss option as well as the standard one: aggressive cuts are not always the smarter choice.

Who this calculator is for

This tool turns your body stats into a concrete daily calorie target. It is useful for:

• People starting a diet who need a realistic deficit instead of guessing or crash-dieting.
• Anyone trying to gain weight or muscle who needs a surplus paired with strength training.
• Maintainers who reached their goal weight and want to know the number that holds it steady.
• Athletes and active people sanity-checking whether they are fueling enough for their training load.
• Anyone curious about how much they actually burn in a typical day.

Key terms explained

• BMR (basal metabolic rate): the calories your body burns at complete rest to stay alive. It is the largest single piece of your daily burn for most people.
• TDEE (total daily energy expenditure): BMR plus the calories from movement, digestion and exercise. This is your maintenance level.
• Calorie deficit: eating fewer calories than your TDEE, which leads to weight loss over time.
• Calorie surplus: eating more than your TDEE, which leads to weight gain - useful for building muscle.
• Activity factor: the multiplier (1.2 to 1.9) applied to BMR to account for how active you are.
• Macronutrients: protein, carbohydrates and fat, the three nutrients that supply calories. Hitting your calorie target while keeping protein high helps protect muscle.

What changes the result the most

If you adjust the inputs and watch the number move, a few factors dominate:

• Body weight: a heavier body burns more at rest, so weight is the single biggest driver of your maintenance number.
• Activity level: jumping from sedentary (1.2) to very active (1.725) can add 600-1,000 calories to your TDEE.
• Sex: men generally have more muscle and a higher BMR than women of the same size and age.
• Age: resting metabolism declines slowly through adulthood, lowering the number over the years.
• Height: taller people have more tissue to maintain and burn modestly more.

Tips to make your target work

• Track for two weeks. Logging your food shows whether you are actually hitting the target - most people under-count by hundreds of calories.
• Prioritize protein. Roughly 0.7-1 gram per pound of body weight helps preserve muscle in a deficit and keeps you full.
• Weigh the trend, not the day. Daily weight swings of a few pounds are mostly water. Look at the weekly average.
• Re-check every few weeks. As your weight changes, so does your maintenance level - recalculate to keep the deficit accurate.
• Don't drop too low. A moderate deficit you can sustain beats an extreme one you abandon in a week.

Where your calories actually come from

A calorie is simply a unit of energy, and your food supplies it through three macronutrients. Protein and carbohydrate each provide about 4 calories per gram, fat provides about 9 calories per gram, and alcohol adds roughly 7. That is why fatty and fried foods, oils, nuts and alcohol pack calories into small portions while vegetables and lean protein fill your plate for far fewer. Two meals can hit the same calorie total and feel completely different: a plate of chicken, rice and broccoli is bulky and filling, whereas a pastry and a sugary coffee can match it in calories yet leave you hungry an hour later. Understanding this "calorie density" is the single most useful habit for sticking to a target without feeling deprived. The calculator gives you the number; how you spend it decides how easy that number is to live with.

The four parts of your daily burn

Your total daily energy expenditure is not one thing - it is the sum of four components, and knowing them explains why two people of the same size can need very different amounts:

• BMR (about 60-70% of the total): the energy to keep you alive at rest. It is mostly driven by your size and lean mass, which is why heavier and more muscular people burn more even sitting still.
• NEAT - non-exercise activity thermogenesis (15-30%): all the movement that is not formal exercise - walking, standing, fidgeting, chores, taking the stairs. NEAT varies enormously between people and quietly shrinks when you diet, which is one reason weight loss slows.
• TEF - thermic effect of food (about 10%): the calories burned digesting and processing what you eat. Protein has the highest TEF, another reason higher-protein diets help with fat loss.
• Exercise (0-30%, highly variable): deliberate training. For most non-athletes this is the smallest slice, which surprises people who assume a single workout offsets a big meal.

The activity factor in this calculator rolls NEAT, TEF and exercise into one multiplier on top of your BMR. That is why honest activity selection matters so much - it is standing in for three different things at once.

Common scenarios and what to enter

Most people fall into one of a handful of situations. Here is how to translate each into the right inputs and goal:

• Office worker who wants to lose a few pounds: pick sedentary or lightly active (a couple of gym visits do not make a desk job "moderate"), then use the standard -500 loss target. If the floor feels too low, drop to the gentler -250.
• Regular gym-goer training 4-5 times a week: moderately active is usually right; very active is for physical jobs or twice-a-day training. Resist the urge to round up.
• Skinny person trying to build muscle: choose your real activity level and use the +500 gain target, paired with progressive strength training so the surplus builds muscle rather than just fat.
• Postpartum or returning from a break: recalculate from your current weight and activity, not the numbers from before - both change quickly.
• Athlete in heavy training: the upper factors (1.725-1.9) may still undercount very high training volumes; use the figure as a floor and add fuel around big sessions.

When two levels feel equally plausible, choose the lower one. It is easier to add food when the scale stalls than to claw back a deficit you never actually had.

Exercise vs. diet: which moves the number?

It is tempting to "earn" food with workouts, but the math usually favors the plate. A 30-minute jog might burn 250-350 calories, roughly the amount in a single muffin or a couple of glasses of wine - so it is far easier to not eat the surplus than to run it off. Exercise is still worth doing for health, mood, appetite control and, crucially, for preserving muscle while you lose fat. The right mental model is that diet sets the size of your deficit and exercise protects the quality of the weight you lose. Because your chosen activity level already bakes typical workouts into the TDEE figure, you should not also add tracker-reported "calories burned" on top - doing so is the most common reason a deficit silently disappears. If you specifically want to plan around training calories, the TDEE Calculator and the Calorie Deficit Calculator let you model the trade-off more directly.

When the scale won't move: how to adjust

If you have eaten at your target consistently for 2-4 weeks and your weekly average weight has not budged, work through this checklist before assuming the calculator is wrong:

1. Tighten tracking for one week. Weigh foods rather than eyeballing, and log oils, sauces, drinks and bites. Under-counting by 200-400 calories a day is extremely common and erases a deficit.
2. Re-run the calculator with today's weight. As you get lighter your maintenance drops, so a target that worked at the start may now sit at your new maintenance level.
3. Stop eating back exercise calories. They are already included in your activity factor.
4. Account for water. A new training program, a salty meal, poor sleep or (for women) the menstrual cycle can mask several pounds of fat loss for a week or more. Judge the four-week trend, not a single morning.
5. Only then lower the target, by a modest 100-200 calories, or add daily steps to raise your burn rather than cutting food further.

Plateaus are normal and usually a tracking or maintenance-drift problem, not a broken metabolism. A 250-500 calorie deficit you can actually sustain beats an aggressive one you abandon - the most reliable plan is the one you can repeat for months.

A note on special situations

Standard calorie formulas are built for healthy, non-pregnant adults, so a few groups should treat the output with extra caution or skip it entirely. Pregnant and breastfeeding people have higher and changing needs that this tool does not model - follow medical guidance instead. Children and teenagers are still growing and should not follow adult deficit targets. People with thyroid conditions, diabetes, eating-disorder history, or who take medications that affect appetite or metabolism should set targets with a clinician. Older adults can use the calculator but should pay special attention to protein and resistance training to protect against age-related muscle loss. When in doubt, treat the number as a conversation starter with a doctor or registered dietitian rather than a prescription.

Limitations and assumptions

This calculator is a planning estimate, not a precise measurement. Keep these assumptions in mind:

• BMR formulas are accurate to about ±10% and cannot see your individual muscle mass, body composition or genetics.
• The activity factors are broad categories, so two people who both pick "moderately active" may genuinely burn different amounts.
• The 3,500 calories per pound rule is a useful approximation; real fat loss is rarely perfectly linear because metabolism adapts.
• It does not account for pregnancy, breastfeeding, medical conditions or medications, all of which change calorie needs.
• It estimates calorie quantity, not nutritional quality - what you eat matters as much as how much.

How it compares to related calculators

This page answers "how many calories should I eat?" If your question is slightly different, a sister tool fits better:

• For just your maintenance burn, use the TDEE Calculator.
• For your resting metabolism on its own, use the BMR Calculator.
• To split your target into protein, carbs and fat, use the Macro Calculator.
• To plan a specific deficit and timeline, use the Calorie Deficit Calculator.
• To estimate how long reaching a goal weight will take, use the Weight Loss Calculator.
• To check your weight against a healthy range first, use the BMI Calculator or estimate composition with the Body Fat Calculator.

Sources

• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of NIH - Weight Management.
• U.S. Department of Agriculture & U.S. Department of Health and Human Services - Dietary Guidelines for Americans (calorie needs and the 1,200/1,500 lower bounds).
• National Heart, Lung, and Blood Institute (NHLBI), part of NIH - Aim for a Healthy Weight.
• Mifflin MD, St Jeor ST, et al. (1990), American Journal of Clinical Nutrition - the resting energy expenditure equation used here.