Calorie Calculator

Calories are a measure of the energy in food and drink, and of the energy your body uses. Knowing roughly how many you need can help you maintain a healthy weight, lose weight steadily or fuel training. But everyone's needs are different, depending on age, size, sex and how active you are.

This guide explains how daily calorie needs are estimated and how to use them sensibly. To get your own figure, use the calorie calculator.

The NHS guideline figures

As a general guide, the NHS suggests that to maintain a healthy weight:

• Women need around 2,000 kcal a day
• Men need around 2,500 kcal a day

These are averages. A small, inactive person may need less, while a tall, very active person may need much more.

How calorie needs are worked out

Your daily energy needs are made up of two main parts.

1. Basal metabolic rate (BMR)

Your BMR is the energy your body uses at rest to keep you alive: breathing, circulating blood, repairing cells and maintaining your temperature. It usually makes up the largest share of the calories you burn.

The calorie calculator uses the Mifflin-St Jeor equation, one of the most widely used formulas, which estimates BMR from your weight, height, age and sex.

2. Activity

On top of your BMR, you burn energy through movement, from walking and housework to exercise. To account for this, BMR is multiplied by an activity factor:

The result is your estimated maintenance calories: roughly what you'd need to eat each day to stay the same weight.

A worked example

A 35-year-old woman who is 165cm tall, weighs 70kg and does light exercise a few times a week:

• BMR: about 1,400 kcal a day
• Multiplied by 1.375 for light activity: about 1,920 kcal a day to maintain her weight

Try your own details in the calorie calculator.

Calories for weight loss

To lose weight, you need to use more energy than you take in. The NHS advises that losing 0.5kg to 1kg (1lb to 2lb) a week is a safe, realistic rate for most people.

A deficit of about 500 kcal a day typically leads to losing around 0.5kg a week. In the example above, that would mean eating around 1,420 kcal a day. Very low-calorie diets aren't recommended without medical supervision, as they can leave you short of nutrients and are hard to sustain.

Calories for weight gain or muscle building

If you're trying to gain weight or build muscle, eating a modest amount above maintenance, often around 250 to 500 kcal a day, alongside strength training is a common approach. Our one rep max calculator can help plan training loads.

Why your real needs may differ

Any formula is an estimate. Your actual needs can vary because of:

• Body composition. Muscle uses more energy than fat, so two people of the same weight may need different amounts.
• Genetics and hormones, including thyroid function.
• Everyday movement, such as standing, walking and fidgeting, which varies a lot between people.
• Changes over time. As you lose weight, your energy needs usually fall slightly.

The best approach is to use the estimate as a starting point, track your weight over a few weeks and adjust.

Calories aren't the whole story

The quality of what you eat matters as well as the quantity. The NHS Eatwell Guide recommends:

• Basing meals on higher-fibre starchy foods like wholegrain bread, rice and pasta
• Eating at least five portions of fruit and vegetables a day
• Including protein such as beans, pulses, fish, eggs and meat
• Choosing lower-fat dairy or alternatives
• Limiting foods high in fat, salt and sugar

Food labels in the UK show calories per 100g and often per portion, and many use traffic-light colours to help you compare.

Tips for managing your calorie intake

1. Check food labels and portion sizes.
2. Be aware of drinks, which can contain more calories than you'd expect.
3. Plan meals and snacks ahead.
4. Fill up on vegetables, fruit and fibre.
5. Stay active: the UK guidelines recommend at least 150 minutes of moderate activity a week.

Reading UK food labels

Most pre-packed food in the UK shows energy in both kilojoules (kJ) and kilocalories (kcal). The kcal figure is what people usually mean by calories. Labels give values per 100g, so you can compare products fairly, and often per portion too. Check what the manufacturer counts as a portion, as it may be smaller than what you'd actually eat.