Select the amount to solve for, then enter the two known meal values. This educational arithmetic is not a dosing recommendation; use your prescribed care plan.

Educational arithmetic only. Use your prescribed ratio and care plan; this is not a dosing recommendation.

Related Calculators

Carb To Insulin Ratio Formula

The following formula gives meal coverage arithmetic (I) in units from carbohydrates (C) in grams and a prescribed carb-to-insulin ratio (R) in grams per unit. It omits glucose correction, active insulin and other clinical factors.

I = C / R

Variables:

  • I is the insulin dose in units (U)
  • C is the amount of carbohydrates in grams (g)
  • R is the carb-to-insulin ratio (grams per unit)

To calculate the insulin dose, divide the amount of carbohydrates by the carb-to-insulin ratio.

What is Carb To Insulin Ratio?

The carb-to-insulin ratio is a personalized measure used by people with diabetes to determine how many grams of carbohydrates are covered by one unit of insulin. Your diabetes team determines the appropriate ratio and any changes; a ratio calculated from two meal values alone does not establish a prescription.

How to Calculate Carb To Insulin Ratio?

The following steps outline how to use the calculator and formula to determine the carb-to-insulin ratio or insulin dose.

  1. Determine the amount of carbohydrates (C) in grams you plan to consume.
  2. If calculating insulin dose, use your known carb-to-insulin ratio (R).
  3. Insert the variables into the formula I = C / R to find the insulin dose in units.
  4. If calculating the ratio, use known insulin dose (I) and carbohydrates (C) and solve R = C / I.
  5. If calculating carbohydrates, use known insulin dose (I) and ratio (R) and solve C = I × R.

Example Problem:

Use the following variables as an example to test your calculation:

Carbohydrates (C) = 60 g

Carb-to-insulin ratio (R) = 15 g per unit

Insulin dose (I) = C / R = 60 / 15 = 4 units