Calorie Calculator: How Many Calories Should I Eat a Day?

The calculator runs three steps. It estimates the calories you burn at rest, scales that up for how active you are, then adjusts for whether you want to lose, hold, or gain weight. If you want the whole picture first, including how calories are calculated on both sides of the equation, that guide covers food and body together.

Step one is your Basal Metabolic Rate: the energy your body spends staying alive, breathing, circulating blood, and running your organs. Calora estimates it with the Mifflin-St Jeor equation.

For men: (10 × kg) + (6.25 × cm) − (5 × age) + 5
For women: (10 × kg) + (6.25 × cm) − (5 × age) − 161

Step two multiplies that BMR by an activity factor between 1.2 and 1.9 to give your Total Daily Energy Expenditure. Step three adds or subtracts calories for your goal.

Mifflin-St Jeor is used instead of the older Harris-Benedict equation because it is more accurate for most people. Harris-Benedict dates to 1919, was revised in 1984, and tends to overestimate resting energy expenditure. Mifflin and St Jeor published their equation in 1990 to correct exactly that, and it has been the standard prediction equation since. To see the resting figure on its own, use the BMR calculator.

Take Sarah. She is 34, 165 cm, 72 kg, works at a desk, walks the dog, and lifts twice a week. That makes her lightly active.

Her BMR is (10 × 72) + (6.25 × 165) − (5 × 34) − 161, which comes to 1,420 calories. That is roughly what she would burn lying in bed all day.

Multiply by her activity factor of 1.375 and her TDEE is 1,953 calories. That is her maintenance level: eat that, and her weight holds steady. The maintenance calorie calculator returns the same figure directly.

Sarah wants to lose weight, so she takes 500 off. Her target is about 1,450 calories a day, comfortably above the 1,200 floor. She carries through the next two sections.

Subtract 500 calories from your maintenance level. That is the whole method. For Sarah it means eating about 1,450 calories instead of 1,953.

A 500-calorie daily deficit is 3,500 calories a week, which is roughly 0.45 kg (1 lb) of body weight. That rate is the sensible ceiling for most people, not a minimum to beat. The calorie deficit calculator projects it week by week, and the full guide to how to calculate a calorie deficit walks the arithmetic step by step, including the safety floor.

Aggressive deficits fail for predictable reasons. Very low intakes are hard to sustain, so adherence collapses. You lose more lean tissue alongside the fat, which lowers your BMR and makes the next kilogram harder than the last. Hunger and fatigue climb, and the movement you do without thinking about it quietly falls.

The slower deficit usually wins because people actually stick to it. A 250-calorie deficit held for six months beats a 1,000-calorie deficit abandoned in three weeks.

Protein matters more as the deficit grows. Aim for roughly 1.6 to 2.2 grams per kilogram of body weight to protect lean mass, and set the split with the macro calculator.

This is the biggest source of error in any calorie calculator, and it is not the calculator making the mistake. One step up this ladder is worth roughly 300 calories a day.

Most people pick one level too high. Three gym sessions a week is moderate, not very active. Extra active means hard daily training on top of physical work, and almost nobody reading this qualifies.

When you are unsure, choose the lower option. It is easy to add calories back once the scale starts moving. It is demoralising to discover after two months that you have been eating at maintenance the whole time.

Your calorie target is not a number you calculate once. It falls as you do.

A lighter body costs less to run. When Sarah reaches 66 kg, her BMR drops to about 1,360 and her TDEE to roughly 1,870. The 500-calorie deficit she set at 72 kg is now about a 420-calorie deficit against her current maintenance, and her weekly loss slows to match.

This is the usual explanation for a plateau. Nothing is broken and your metabolism has not stopped working. The deficit shrank while you were not looking.

Recalculate every four to six weeks, or whenever you lose about 5 kg (10 lb). It takes thirty seconds, and it is the difference between a plan that keeps working and one that stalls.

1. Drinking your calories. Juice, lattes, alcohol, and smoothies are easy to miss and easy to repeat. A daily large latte and a glass of wine can cancel most of a 500-calorie deficit on their own.
2. Eating back the calories your tracker says you burned. Fitness trackers and gym machines tend to overstate exercise burn, and your TDEE already includes your activity level, so eating those calories back double-counts them. Get a realistic figure from the calories burned calculator, and see how to calculate calories burned for why the number on your watch is usually too high.
3. Overestimating your activity level. The most common error on this page, and worth about 300 calories a day. See the table above.
4. Weighing yourself daily and reacting to it. Day to day, the scale mostly tracks water, salt, and what is still in your gut. A kilogram gained overnight is not fat. Weigh at the same time each day if it helps, but judge progress on a weekly average.
5. Ignoring protein. Two people eating 1,500 calories can lose very different amounts of muscle. Protein preserves lean mass in a deficit and keeps you fuller on fewer calories. It is the macro that most changes the outcome.