ISF & I:C Calculator
Calculate your Insulin Sensitivity Factor (ISF) and Insulin-to-Carb Ratio (I:C) based on your Total Daily Dose (TDD).
Calculation
I:C
500 ÷ 40 = 12.5 g/U
ISF
1800 ÷ 40 = 45.0 mg/dL ÷ 18 = 2.5 mmol/L
Insulin-to-Carb Ratio (I:C)
500 ÷ TDD
1:12.5
grams of carbs per 1 U of insulin
Insulin Sensitivity Factor (ISF)
1800 ÷ TDD
2.5 mmol/L
(45.0 mg/dL)
About ISF & I:C
- I:C (Insulin-to-Carb Ratio): How many grams of carbohydrates are covered by 1 unit of insulin. Calculated as 500 ÷ TDD.
- ISF (Insulin Sensitivity Factor): How much your blood glucose drops per 1 unit of insulin. Calculated as 1800 ÷ TDD.
- Rules: The "500 rule" and "1800 rule" are starting-point estimates. Your actual values may differ and should be fine-tuned with your healthcare provider.
Disclaimer
This calculator is for educational purposes only. The 500 and 1800 rules provide rough estimates. Always consult with your healthcare provider before adjusting insulin dosing parameters.