Understanding Your Carb-to-Insulin Ratio
Your carb-to-insulin ratio (ICR) is the number of grams of carbohydrate covered by one unit of rapid-acting insulin. A ratio of 1:10 means one unit covers 10g of carbs. To estimate a mealtime dose, divide the meal’s carbs by your ratio. Your ratio is set with your healthcare provider — it is personal and can change.
What is a carb-to-insulin ratio?
A carb-to-insulin ratio — also called an insulin-to-carb ratio (ICR) — tells you how many grams of carbohydrate one unit of rapid-acting insulin will cover for you. It is the bridge between the carbs you count and the insulin you take at a meal.
It is usually written as 1:X, where X is the grams of carb per unit. A 1:10 ratio means one unit covers 10 grams of carbohydrate; a 1:15 ratio means one unit covers 15 grams.
How the ratio is used
To estimate a mealtime dose, divide the total carbs in the meal by the second number in your ratio. With a 1:10 ratio and a 60g meal, that is 60 ÷ 10 = 6 units of insulin for the food.
A larger second number (for example 1:20) means you need less insulin per gram of carb; a smaller number (for example 1:5) means you need more. Some people use different ratios at different times of day because insulin sensitivity changes from morning to night.
Where your ratio comes from
Your ratio is personal and is determined with your healthcare team, often starting from an estimate based on your total daily insulin and then fine-tuned by reviewing your glucose after meals. It is not a fixed universal number, and it can change with weight, activity, illness, pregnancy, or other factors.
Never change your ratio on your own. CarbTrack stores the ratio you enter and uses it for calculation only — it does not set or recommend a ratio.
How CarbTrack uses your ratio
You enter your ratio once in the app. When you log a meal, CarbTrack divides the carb count by your ratio to show an estimated food dose, and it can add a correction dose if you configure one. The result is a calculation based entirely on the numbers you provide — always confirm it against your care plan before dosing.
Frequently asked questions
What does a 1:10 carb ratio mean?
It means one unit of rapid-acting insulin is expected to cover 10 grams of carbohydrate for you. To estimate a dose, divide the meal’s carbs by 10.
Can my carb ratio change?
Yes. Insulin sensitivity changes with time of day, activity, weight, illness, and pregnancy, so your ratio may be adjusted by your care team. Some people use different ratios for breakfast, lunch, and dinner.
Does CarbTrack set my carb ratio?
No. You enter the ratio your healthcare provider gives you. CarbTrack uses it only to calculate an estimated dose — it does not recommend or change ratios.
Sources
CarbTrack does this math for you — instantly, from a photo or a food search.
Download CarbTrackCarbTrack is a calculator tool only. Not a medical device. Not medical advice. Insulin dose calculations are based solely on the carb ratio you provide. Always consult your healthcare provider before making changes to your insulin regimen or diabetes management plan.