How to Calculate Your Daily Calories: BMR, TDEE and Worked Examples

What are daily calories?

Your daily calories are the amount of energy your body burns in one day. Part of it is spent just to keep you alive, and part is spent on everything you do, from walking to the shop to training in the gym. If you eat about that amount, your weight stays steady. If you eat less, your body uses stored energy, and if you eat more, it stores the extra.

No calculator can measure your body exactly, but a good estimate is enough to start. You then watch what happens to your weight over a few weeks and adjust.

BMR and TDEE explained

• BMR. Basal metabolic rate is the energy your body uses at complete rest, for breathing, circulation, keeping warm and running your organs.
• Activity. Walking, working, exercising and even fidgeting burn calories on top of your BMR.
• TDEE. Total daily energy expenditure is your BMR plus the calories you burn through activity. It is the number that matters for your daily target.
• Maintenance calories. This is another name for TDEE. Eating this amount should keep your weight steady.

The formula behind a calorie calculator

Most calorie calculators use the Mifflin-St Jeor equation, which is widely used. For men, BMR = 10 x weight in kg + 6.25 x height in cm - 5 x age + 5. For women, BMR = 10 x weight in kg + 6.25 x height in cm - 5 x age - 161.

To get your TDEE, multiply your BMR by an activity factor. The factor depends on how active your week is, and the next sections show the values.

Worked example: a 30-year-old man

Take a man who is 30 years old, weighs 80 kg and is 180 cm tall. His BMR is 10 x 80 + 6.25 x 180 - 5 x 30 + 5, which is 800 + 1,125 - 150 + 5 = 1,780 calories a day. If he is lightly active, he multiplies by 1.375, so his maintenance calories are about 2,448 a day.

Now take a woman who is 28, weighs 65 kg and is 165 cm tall. Her BMR is 10 x 65 + 6.25 x 165 - 5 x 28 - 161, which is about 1,380 calories. With the same light activity, her maintenance is about 1,898 calories a day.

Step-by-step: finding your calories

• Step 1: Choose your units. Use kilograms and centimeters, or pounds, feet and inches. The calculator handles both.
• Step 2: Enter your details. Add your sex, age, weight and height. Use your current weight and a measured height.
• Step 3: Pick your activity level. Choose the level that matches a normal week, not your best week. When in doubt, pick the lower one.
• Step 4: Read your numbers. You get your BMR, your maintenance calories and targets for your goal.
• Step 5: Start and watch. Follow the number for two to three weeks and compare it with your weight trend.

Choosing your activity level

• Sedentary (x 1.2). A desk job with little or no exercise.
• Lightly active (x 1.375). Light exercise or sport 1 to 3 days a week.
• Moderately active (x 1.55). Moderate exercise 3 to 5 days a week.
• Very active (x 1.725). Hard exercise 6 to 7 days a week.
• Extra active (x 1.9). Very hard exercise combined with a physical job, or training twice a day.

Calories for weight loss, maintenance and weight gain

A common starting point for weight loss is 250 to 500 calories below maintenance. For the man above, 500 below 2,448 is about 1,948 calories, which is still above his BMR of 1,780. A deficit of 500 calories a day adds up to about 3,500 a week, which is roughly half a kilogram of body fat a week by the usual rough estimate.

For weight gain, add 250 to 500 calories above maintenance. A target that falls below your BMR is a warning sign that the cut is too big, because it makes tiredness, lost muscle and rebound eating more likely.

How accurate is a calorie calculator?

A calculator gives an estimate, not a measurement. Two people with the same numbers can burn quite different amounts because of muscle, genetics, sleep and daily movement. The formula is a good starting point, and your real results over a few weeks are the final answer.

If your weight does not change in two to three weeks, adjust your intake by about 100 to 200 calories and watch again.

Common calorie mistakes

• Overestimating activity. Choosing a higher level than you really have makes the target too high.
• Cutting too much, too fast. Very large deficits cause tiredness, lost muscle and rebound eating.
• Ignoring liquid calories. Juices, soft drinks, sweet coffee and alcohol add up quickly.
• Not weighing portions. Portions are often larger than people think, which makes tracking inaccurate.
• Expecting a straight line. Progress is uneven, so judge it over weeks, not days.

Who should speak to a professional first?

Calorie calculators are meant for healthy adults. If you are pregnant or breastfeeding, under 18, have a medical condition, take regular medicine or have ever struggled with disordered eating, talk to a doctor or a registered dietitian before you change how you eat. They can give advice that fits you.

Calculate your calories now

Use our free calorie calculator to see your BMR, your maintenance calories and your targets in seconds. Your numbers stay in your browser and are never uploaded. You can also check your BMI with the BMI Calculator.

Frequently asked questions