Calorie Calculator

Calorie Calculator: How Many Calories Do You Need Each Day?

What Does a Calorie Calculator Do?

A calorie calculator estimates how many calories your body uses in a day, often called your maintenance calories. If you eat about that amount, your weight tends to stay steady. Eat more and you gain weight, eat less and you lose it. The tool takes your age, sex, height, weight and activity level and applies a standard equation to give you a daily target.

The number is an estimate based on averages. Your real needs can be higher or lower, so treat it as a starting point and adjust based on how your weight changes over a few weeks.

How Your Daily Calories Are Calculated

The calculation has two steps.

1. Find your BMR. Basal metabolic rate (BMR) is the energy your body burns at complete rest to keep you alive: breathing, circulation, keeping warm and repairing cells.
2. Multiply by an activity factor. This adds the calories you burn moving through your day. The result is your total daily energy expenditure (TDEE), which is your maintenance level.

Typical activity factors

The Three Equations Calorie Calculators Use

Different calculators use different equations to find BMR. Here are the three most common. In each, W is weight in kilograms, H is height in centimetres and A is age in years.

Which one is best?

• Mifflin-St Jeor was introduced in 1990 and is generally considered the most accurate for most people, which is why many calculators use it.
• Harris-Benedict is older (revised in 1984) and tends to be a little less accurate.
• Katch-McArdle uses lean body mass instead of total weight, so it can be more accurate for lean people who know their body fat percentage.

Calorie Calculator Example

Take a 28-year-old woman who weighs 65 kg, is 165 cm tall and exercises three to five days a week.

1. BMR (Mifflin-St Jeor) = 10 × 65 + 6.25 × 165 − 5 × 28 − 161 = 650 + 1,031 − 140 − 161 = about 1,380 calories.
2. Activity factor for moderate exercise = 1.55.
3. TDEE = 1,380 × 1.55 = about 2,140 calories a day to maintain her weight.

For comparison, a 30-year-old man who weighs 80 kg and is 178 cm tall has a BMR of about 1,770 calories. At the same activity factor his maintenance level is around 2,740 calories.

How Many Calories Do You Need to Lose or Gain Weight?

One pound (about 0.45 kg) of body weight is roughly equal to 3,500 calories. That gives a simple rule of thumb: eating about 500 calories a day below maintenance leads to a loss of around one pound a week, and eating about 500 above leads to a gain of about the same.

Using the woman in the example above, a daily intake of about 1,640 calories (2,140 − 500) would be a moderate deficit. Real results vary, because your metabolism changes as your weight changes, and water retention can hide progress from day to day.

Keep these limits in mind:

• Aim for a loss of about 0.5 to 1 kg (1 to 2 lb) a week at most. Faster loss often means losing muscle and water, and can lower your metabolic rate.
• Harvard Health suggests that women should not go below 1,200 calories a day and men below 1,500 unless a doctor is supervising.
• Eating too little makes it hard to get enough protein, fibre, vitamins and minerals.

If you want to see how a deficit works in detail, use a calorie deficit calculator along with this one.

How Many Calories Do You Need in Pregnancy?

Pregnancy is not a time to cut calories or try to lose weight. Your needs go up, though not as much as the old saying “eating for two” suggests. A commonly cited guide for a single baby is:

These amounts are added to your pre-pregnancy needs, and they vary with your weight, activity and health. Your doctor or midwife can tell you what is right for you. To plan healthy weight gain, check your starting category with our BMI calculator, and track your weeks with the pregnancy calculator.

Does Calorie Counting Work?

For many people, yes. At its simplest, weight depends on calories in versus calories out: eat more than you burn and you gain, eat less and you lose. Counting can help because it:

• shows you how many calories your usual foods and drinks really contain,
• makes portion sizes easier to judge,
• gives you a clear target instead of a vague plan to “eat less”,
• and shows how much exercise it takes to burn off a snack.

It is not for everyone. If counting makes you anxious or obsessive about food, choose another approach and talk to a doctor or dietitian, especially if you have ever had an eating disorder. The best method is the one you can keep up.

A simple way to start

1. Use the calorie calculator to find your maintenance level.
2. Choose a modest goal, such as a 250 to 500 calorie change per day.
3. Track what you eat with a phone app, a spreadsheet or a notebook. Weighing portions for a week or two helps you estimate more accurately afterwards.
4. Check your progress weekly rather than daily, and weigh yourself under the same conditions each time, such as first thing in the morning.
5. Adjust your intake if your weight isn’t moving as expected after two to three weeks.

Quality Matters as Well as Quantity

A calorie is a unit of energy, but the food it comes from affects hunger, nutrition and health. Foods that are rich in fibre and protein, such as vegetables, fruit, lean meat, beans and whole grains, tend to keep you fuller for longer. Your body also uses a little extra energy to digest them (the thermic effect of food), though the difference is small.

Calories per gram

High-calorie, low-calorie and empty-calorie foods

• High-calorie foods pack many calories into a small serving. Some are very nutritious, such as nuts, avocado and whole grains, so they are not automatically “bad”.
• Low-calorie foods include most vegetables and many fruits. They give you volume and nutrients for few calories.
• Empty calories come from added sugar and solid fats and give few nutrients. Sugary drinks are the most common example.

Drinks are easy to overlook. Juice, sweetened coffee, soda and alcohol can add a lot of calories without making you feel full. Water, plain tea and black coffee have almost none.

Approximate calories in common foods

Values differ between brands, cooking methods and portion sizes, so use them as a guide only.

Calories Burned by Common Activities

Exercise raises your daily energy use, but it burns less than most people expect. Approximate calories burned in one hour:

Heavier people burn more calories doing the same activity. Anyone who is pregnant or has a health condition should check with a doctor before starting a new exercise routine.

What Is Zigzag Calorie Cycling?

Zigzag calorie cycling means varying your calories from day to day while keeping the weekly total the same. People use it to add flexibility, for example to eat more on a day with a family meal and less on other days. Some also believe it helps avoid a plateau, although the evidence for that is limited.

Example: suppose your weekly target is 12,600 calories, an average of 1,800 a day. You could eat 1,800 every day, or eat 2,100 on two days and 1,680 on the other five. Both add up to 12,600.

A common approach is to keep high and low days within about 200 to 300 calories of each other. There is no single best pattern, so choose one you can follow.

Tips for a More Accurate Result

• Enter your current weight, not your goal weight.
• Be honest about your activity level. Most people overestimate it.
• If you know your body fat percentage, try an equation that uses lean body mass.
• Retest your calories after you lose or gain a few kilos, since your needs change.
• Use your weight trend over two to three weeks to fine-tune the estimate.

Calorie Calculator FAQs

How many calories should I eat a day?

It depends on your age, sex, height, weight and activity. Typical ranges are about 1,600 to 2,400 for women and 2,000 to 3,000 for men to maintain weight.

What is the difference between BMR and TDEE?

BMR is the energy you burn at rest. TDEE is your BMR plus the calories you use for daily activity and exercise.

Which calorie equation is the most accurate?

Mifflin-St Jeor is generally the most accurate for most people. Katch-McArdle can be better for lean people who know their body fat percentage.

How many calories should I cut to lose weight?

A deficit of about 250 to 500 calories a day is sustainable for most people, giving roughly 0.25 to 0.5 kg (0.5 to 1 lb) of loss per week. Avoid very low intakes unless a doctor is supervising.

Do I need extra calories when pregnant?

Usually not in the first trimester. Guidance is around 340 extra calories a day in the second trimester and about 450 in the third, but your doctor can advise you personally.

Is calorie counting safe for everyone?

No. If you are pregnant, have a history of disordered eating or a medical condition, speak to a doctor or dietitian first.