Calories are a well-known measure of the amount of energy in food. Keeping track of the number of calories in our food helps us to balance the energy we put into our bodies with the energy we use every day, leading to a healthy weight.
Go straight to 100-calorie portions of:
The term calorie is a commonly used shorthand for ‘kilocalorie’. On food packets you will find this written as kcal. Kilojoules (kJ) are the metric measurement of calories, and you’ll see both kJ and kcal on nutrition labels – 4.2kJ is equivalent to approximately 1kcal.
Within a healthy balanced diet, women need on average 8,400kJ a day (2,000kcal), while men need on average 10,500kJ a day (2,500kcal).
A rough guide as to how your energy requirement can be spread throughout the day is as follows:
As you can see, any drinks or snacks you have count towards your daily energy total. If you eat more for your breakfast, lunch or evening meal, you may need to drop a snack later in the day to stay on track.
This guide shows energy values for 10 different foods. This will help you to visualise what 100kcal (420kJ) looks like and manage the number of calories you consume.
This amount, 100kcal, represents just 5% of a woman’s daily reference intake (4% for men), but this quickly adds up when adding ingredients during cooking or when we reach for a snack. High-fat foods have more energy per bite, while foods containing water, such as vegetables, have less.
These are not suggestions for snacks. They simply show how quickly calories can add up in certain foods. Some of the photos also show household objects, such as a pack of cards, to help illustrate the portion size.
Oil is pure fat, which is why you only get a little over one tablespoon of olive oil; one level tablespoon of mayonnaise and just under one tablespoon of butter (a thick spread of butter on your bread) for 420kJ / 100kcal each.
Most cheese is high in fat, so for 420kJ / 100kcal you get just under a 30g matchbox-sized piece of Cheddar cheese.
Calories in the white stuff can add up if not used sparingly, especially for people who drink tea or coffee with sugar throughout the day. Four heaped teaspoons of sugar is 420kJ / 100kcal.
A lot of biscuits are high in fat and sugar and low in nutrients, so two ginger nut biscuits add up to 420kJ / 100kcal. Other biscuits may be higher in energy.
Crisps, which are often high in fat and salt, can quickly add up to 420kJ / 100kcal. For example, the 190g tube of crisps featured in this picture contains nearly 1,000 calories, so just 10% of a tube (nine crisps) equals 420kJ / 100kcal.
A thick slice of wholegrain bread is around 100kcal and is a nutritious choice. A plain bagel is much more dense, so you’d get about half a bagel for 420kJ / 100kcal.
The kind of meat you eat could make a big difference to the amount of energy you get. For example, you get just a few bites of steak for 100kcal.
On the other hand, turkey and fish are both low in fat and lower in energy, so for 420kJ / 100kcal you can get three slices of turkey or a pile of large prawns.
Bear in mind, though, that this number of prawns would be high in salt so you wouldn’t want to eat these all at once.
The calories in dried fruit can add up quickly as the water has been removed, making it more dense. For 420kJ / 100kcal you’ll only get just over a 30g portion of raisins, which counts as one of your 5 A DAY.
But for the same amount of energy you could eat two larger portions of different fruits, such as 80g of grapes and 80g of cherries, which together add up to 100kcal and count as two of your 5 A DAY.
Fruit is a healthy quick win when it comes to counting calories. For 420kJ / 100kcal you can tuck into any of the following: a large apple; a banana; up to a punnet of strawberries or one-and-a-half grapefruit. These count towards your 5 A DAY, which should include a variety of fruit and vegetables.
Last but definitely not least, vegetables generally contain the lowest number of calories, while bringing the added benefits of vitamins and minerals.
To illustrate this, 420kJ / 100kcal is equal to any of the following: three whole cucumbers; two heads of lettuce or three carrots weighing around 120g each.
Remember, this page is only intended as an illustration, as all foods vary in energy content and this can depend on how they are made or prepared and on how much you eat. Most pre-packaged foods have a nutrition label on the side or back of the packaging, which will give a guide to the energy content.
Get advice on counting calories in non-packaged foods such as loose fruit and vegetables or fresh bread.
For more information about energy values in food, see Understanding calories.
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.