Carb Counting Calculator
Add up the carbohydrates in a meal and convert the total into carb exchanges (servings of 15 g each). Enter the carb grams for up to four foods and this calculator returns the meal total and the number of exchanges — handy for diabetes meal planning and insulin dosing.
Formula
Total carbs = sum of food carbs; Exchanges = total ÷ 15
- Add the carbohydrate grams from each food to get the meal total.
- One carb exchange (or carb choice) equals about 15 g of carbohydrate, so exchanges = total ÷ 15.
- Exchanges make insulin dosing simpler when you use a units-per-exchange plan.
- Read carb grams from nutrition labels (per actual portion) or a food database.
- For insulin dosing, pair this with your insulin-to-carb ratio.
- This is a planning aid, not medical advice — follow your care team's guidance.
30 g + 15 g across two foods
Inputs
- Food 1 carbs: 30 g
- Food 2 carbs: 15 g
- Food 3 carbs: 0 g
- Food 4 carbs: 0 g
Total = 30 + 15 = 45 g of carbs. Exchanges = 45 ÷ 15 = 3 carb exchanges for the meal.
Frequently asked questions
What is a carb exchange?
It's a standard serving of carbohydrate equal to about 15 g. Counting exchanges (or carb choices) simplifies meal planning and insulin dosing for many people with diabetes.
Where do I find the carb grams?
Use the nutrition label for the actual portion you eat, or a trusted food database. Enter the grams for each food and the calculator totals them.
How do exchanges relate to insulin?
If your plan uses a fixed insulin dose per exchange, multiply the exchanges by that dose. If you use an insulin-to-carb ratio, work from the gram total instead.
Does fibre count?
This tool uses total carbohydrate. If you track net carbs, subtract fibre from each food's total before entering it.
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