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Food Exchange Calculator
Count the carbohydrate in a meal as 10g carbohydrate portions or 15g exchanges
Values are per 100g from our own food database, scaled to the amounts shown. Counts carbohydrate only. This is a guide, not medical or dietary advice, and it does not work out insulin or medicine doses.
A free food exchange calculator for the UK. Search for the foods in a meal, enter how many grams of each you will eat, and the calculator shows the carbohydrate in grams and as carbohydrate portions, using the 10g portion used in UK carb counting, the 15g exchange used by some other systems, or a size you choose. It counts carbohydrate only. It does not work out insulin or medicine doses. No sign-up, and nothing you enter is saved.
How to Use the Food Exchange Calculator
- Choose a portion size: 10g (the UK carbohydrate portion), 15g (exchange), or type your own.
- Search for a food and tap it to add it to your meal. It is added at 100g, or tap one of the quick examples.
- Change the amount of each food, in grams, to match what you will eat.
- Read the result. Each food shows its carbohydrate and portions, and the meal total shows at the bottom. Each food also shows how many grams make one portion.
What Is a Carbohydrate Portion or Food Exchange?
Carbohydrate portions and food exchanges are two ways of counting the carbohydrate in food in fixed-size steps instead of exact grams. Diabetes UK says carbohydrate can be counted in two ways, in grams or as carbohydrate portions, and that one portion is usually equal to 10g of carbohydrate (Diabetes UK, Learn about carb counting). NHS Scotland's carbohydrate counting guide says the same: one carbohydrate portion (CP) is equal to 10g of carbohydrate (NHS Scotland, My Diabetes My Way: Carbohydrate Counting).
A food exchange list is an older, related idea. It groups foods, such as starch and fruit, so that one serving from a group gives about the same carbohydrate. The diabetes.co.uk exchange guide describes a starch serving and a fruit serving as 15g of carbohydrate each (diabetes.co.uk, Food exchange). So 10g and 15g are both in use, and which one applies to you depends on the system your diabetes team or dietitian uses.
10g or 15g: Which Portion Size Should You Use?
Use the size your own diabetes team or dietitian has given you. The calculator starts at 10g because that is the UK carbohydrate portion in the sources above. Choose 15g if you were taught exchanges of that size, or type a custom size if you were given a different one. The grams of carbohydrate do not change when you switch, only how they are grouped into portions, so a meal of 64.4g carbohydrate is 6.4 portions at 10g and 4.3 exchanges at 15g.
Example: A Breakfast Counted in Portions
This example is taken straight from the calculator, using the carbohydrate values in our food database. Open it in the calculator to change the foods or amounts.
| Food | Amount | Carbohydrate | 10g portions |
|---|---|---|---|
| Porridge oats (dry) | 40g | 27.0g | 2.7 |
| Banana (raw) | 120g | 27.4g | 2.7 |
| Semi-skimmed milk | 200g | 10.0g | 1.0 |
| Meal total | 64.4g | 6.4 (4.3 at 15g) |
Each portion in the last column is the food's carbohydrate divided by 10g. Check the pack label for the product you actually eat, because brands differ.
How Many Grams of a Food Make One Portion?
Dividing the portion size by a food's carbohydrate per 100g, then multiplying by 100, gives the weight that makes one portion. These are real values from our database. Tap a weight to see it in the calculator.
| Food | Carbs per 100g | 1 UK portion (10g) | 1 exchange (15g) |
|---|---|---|---|
| Porridge oats (dry) | 67.5g | about 15g | about 22g |
| White bread | 49.3g | about 20g | about 30g |
| White rice (cooked) | 30g | about 33g | about 50g |
| Pasta, white (cooked) | 30.9g | about 32g | about 48g |
| Potatoes, old, boiled | 17.5g | about 57g | about 86g |
| Apple (raw, with skin) | 13.8g | about 72g | about 109g |
| Banana (raw) | 22.8g | about 44g | about 66g |
| Semi-skimmed milk | 5g | about 200g | about 300g |
Cooked and dry foods are very different, so weigh a food in the state our data describes. For example, 100g of cooked white rice has far less carbohydrate than 100g of dry rice. For help swapping one food for another at the same carbohydrate, use our Food Swap Calculator and choose Carbs.
How the Calculation Works
Every food in our database is stored per 100g. The calculator works out the carbohydrate in your amount as carbohydrate per 100g times your grams, divided by 100. It then divides that by the portion size to get portions. For 40g of porridge oats with 67.5g carbohydrate per 100g: 67.5 times 40 divided by 100 is 27.0g, which is 2.7 portions at 10g. The calculator uses the carbohydrate value we hold for each food and does not subtract fibre. If a food has no carbohydrate value, it is left out of the total and the page tells you.
What This Calculator Does Not Do
It counts carbohydrate and shows portions. It does not calculate insulin or any other medicine dose, and it cannot tell you how much carbohydrate you should eat. Diabetes UK explains that your diabetes healthcare team will help you work out your insulin-to-carb ratio, and that you should speak to your team for help (Diabetes UK, Learn about carb counting). NHS Scotland describes a ratio of one unit of insulin for every 10g of carbohydrate as a starting point for most people, not a fixed rule (NHS Scotland, My Diabetes My Way: Carbohydrate Counting). Please ask your diabetes team or a registered dietitian before you use any carbohydrate figure to make a treatment decision.
Sources
- Diabetes UK, Learn about carb counting
- NHS Scotland, My Diabetes My Way: Carbohydrate Counting
- diabetes.co.uk, Food exchange
Food values come from our own food database, per 100g. They may differ from the label on the exact product you eat.
This page is general information, not medical or dietary advice. If you have diabetes, or you are changing your diet for a health reason, speak to your doctor, diabetes team or a registered dietitian.Frequently Asked Questions
What is a food exchange?
A food exchange is a fixed-size serving of a food group, such as starch or fruit, that gives about the same carbohydrate as one serving of another food in that group. Exchanges are used in some diabetes meal-planning systems. In UK carb counting, the equivalent step is a carbohydrate portion.
How many grams of carbohydrate is one portion in the UK?
Diabetes UK says one carbohydrate portion is usually equal to 10g of carbohydrate. NHS Scotland's carbohydrate counting guide gives the same figure. Your own team may use a different size, so check with them.
Is one exchange 10g or 15g?
Both sizes are used. The 10g portion is the UK carbohydrate portion. Some exchange systems use 15g, and the diabetes.co.uk exchange guide describes starch and fruit servings as 15g of carbohydrate. This calculator lets you choose 10g, 15g or your own size.
Can I use this to work out my insulin dose?
No. This calculator only counts carbohydrate and portions. It does not calculate insulin or any medicine dose. Your diabetes healthcare team sets your insulin-to-carb ratio with you, so ask them before using any carbohydrate figure to make a treatment decision.
Why is my total different from the pack label?
We use the carbohydrate value in our food database for each food, which is usually a general value rather than your exact brand. Cooking also changes weight. For a packaged product, the label on the pack is the better figure.
Does the calculator subtract fibre?
No. It uses the carbohydrate value we hold for each food and does not subtract fibre. If your team asks you to count differently, follow their advice.
Is the food exchange calculator free?
Yes, it is free with no sign-up, and nothing you enter is saved. You can copy a link to share a meal.