Calorie calculator

Everyone’s calorie needs are different – they depend on your body, your goals, and your lifestyle. Eating too many or too few calories can affect your energy, weight, and overall health.

How does the calorie calculator work?

The calorie calculator uses a formula known as the Mifflin-St Jeor equation, a widely recognised method for estimating Basal Metabolic Rate (BMR), the number of calories your body burns at rest. It then factors in your activity level to calculate your Total Daily Energy Expenditure (TDEE), which is the number of calories you need to maintain your current weight.

To get an accurate result, simply enter your:

• Age

• Sex

• Weight

• Height

• Physical activity level (from sedentary to very active)

The calculator then estimates your daily calorie requirements to maintain, lose, or gain weight.

How many calories do I need?

The number of calories you need each day depends on several factors:

• Your body composition (muscle mass burns more calories than fat)

• Your level of physical activity

• Your age and sex

• Your health and weight goals

As a general guide:

• Adult women typically need between 1,800 and 2,400 calories per day

• Adult men usually require between 2,200 and 3,000 calories per day

If you're aiming to lose weight, a calorie deficit of 500–1,000 calories per day can lead to a safe and sustainable weight loss of around 0.5 to 1kg (1–2 pounds) per week. To gain weight or muscle, you'll need to be in a calorie surplus, eating more calories than your body burns.

How to calculate calories

You can estimate your calorie needs manually using the Mifflin-St Jeor formula:

For men:
BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5

For women:
BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161

Once you have your BMR, multiply it by your activity level:

• Sedentary (little or no exercise): BMR × 1.2

• Lightly active (light exercise 1–3 days/week): BMR × 1.375

• Moderately active (moderate exercise 3–5 days/week): BMR × 1.55

• Very active (hard exercise 6–7 days/week): BMR × 1.725

• Extra active (intense training or physical job): BMR × 1.9

This gives you your Total Daily Energy Expenditure (TDEE), the number of calories to maintain your current weight.

How accurate is the calorie calculator?

While this calorie calculator provides a useful estimate, it’s important to remember that no online tool can account for every individual variable. Metabolism varies from person to person, and factors like muscle mass, hormones, sleep quality, and medical conditions can all affect how your body uses energy.

To get the most accurate results:

• Be honest about your activity level

• Reassess your calorie needs regularly as your weight or goals change

• Use the calculator as a starting point, then adjust based on real-world results

For personalised advice, especially if you have a health condition, it’s best to speak with a GP, dietitian or qualified nutritionist.

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