Insulin Dosage Calculator

Determines the total mealtime insulin dose, as well as carbohydrate coverage and insulin correction doses to help with monitoring blood sugar.

Refer to the text below the tool for more information about the insulin calculations and formulas used.

The background/basal insulin dose makes up approximately 40-50% of the total daily insulin dose (TDID) and its role is to replace insulin overnight, when you are fasting and between meals.

The remaining 50-60% of the TDID is made up from carbohydrate coverage and high blood sugar correction insulin doses, which depend on carbohydrate content of the meal and blood sugar levels at the time of the meal.


  • Carbohydrate Coverage Insulin Dose (units) = Meal carbohydrate content / Insulin to carb ratio (the X in 1:X)
  • Insulin to Carb Ratio (IC) = 500/TDID
  • Insulin Dose to Correct High Blood Sugar = (Current blood glucose – target blood glucose) / Insulin sensitivity (correction) factor
  • Insulin Sensitivity Factor (in mg/dL) = 1800/TDID
  • Total Mealtime Insulin Dose (units) = Carbohydrate Coverage Insulin Dose + High Blood Sugar Correction

ACarbohydrate Coverage Insulin Dose

Meal carbohydrate content
Is the Insulin to Carb Ratio known?

BHigh Blood Sugar Correction

Current blood glucose
Target blood glucose
Is the Insulin sensitivity (correction) factor known?
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Note: This will provide an estimation of Total Daily Insulin Dose requirements for diabetes mellitus type 2.


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Steps on how to print your input & results:

1. Fill in the calculator/tool with your values and/or your answer choices and press Calculate.

2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.

Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.


Carbohydrate Coverage Insulin Dose

The insulin dose for food coverage is prescribed as carbohydrate divided by the insulin to carbohydrate ratio. The I:C ratio represents how many grams of carbohydrate are covered or disposed of by 1 unit of insulin.

  • Carbohydrate Coverage Insulin Dose (units) = Meal carbohydrate content / Insulin to carb ratio (the X in 1:X)

Commercial insulin products have varying I:C ratio, from 1:4 to 1:30, with most products having an I:C ratio of 1:12 or 1:15. This means that one unit disposes of 12 to 15 grams of carbohydrate. If unknown the I:C ratio can be estimated as IC = 500/TDID.


Correction Insulin Dose

A measurement of blood sugar should be taken and compared to the target pre-meal blood glucose (this may range from 80 to 130 mg/dL, as established by your medical professional). The difference (if any) will need to be corrected with a correction insulin dose.

Generally, to correct a high blood sugar, one unit of insulin is needed to drop the blood glucose by 50 mg/dL but can range from 15 to 100 mg/dL, depending on individual factors.

To account for this, correction dose will depend on your personal insulin sensitivity factor (which tells exactly how many mg/dL blood sugar you can lower with 1 unit of insulin). If unknown, this can be estimated as Insulin sensitivity factor = 1800/TDID.

  • Insulin dose to correct high blood sugar = (Current blood glucose – target blood glucose) / Insulin sensitivity (correction) factor

The sum of the carbohydrate coverage and correction insulin doses is also known as the total mealtime insulin dose:

  • Total Mealtime Insulin Dose (units) = Carbohydrate Coverage Insulin Dose + High Blood Sugar Correction

Total Daily Insulin Dose (TDID)

When insulin therapy is started, a daily dose is estimated based on patient weight and then updated based on the blood sugar reaction in time, given the patients insulin resistance degree.

  • If the weight is expressed in pounds then TDID = Weight in lbs / 4
  • If the weight is expressed in kilograms then TDID = Weight in kg x 0.55

Hypoglycemia – Low Blood Sugar

Has a sudden start and can be triggered by too little food, skipped meals, too much insulin intake, more activity than usual, vomiting, presence of an acute illness.

Symptoms of hypoglycemia Steps to take action
Shakiness Blurry vision 1. Check blood sugar
Increased heart beat Weakness or fatigue 2. Eat three to four glucose tablets or drink 4 ounces of fruit juice or half a can of regular soda
Sweating Headache 3. Check blood sugar again after 15 minutes
Dizziness Hunger 4. If blood glucose still low, treat again – if symptoms persist, ask for medical assistance.

Hyperglycemia – High Blood Sugar

Has a slow start and can be caused by too much food, too little insulin intake, illness or stress.

Symptoms of hyperglycemia Steps to take action
Extreme thirst Blurry vision 1. Check blood sugar
Need to urinate often Drowsiness 2. Check ketones if blood sugar over 300 mg/dL
Hunger Dry skin 3. Treat with insulin dose
Yeast infection Tiredness 4. If blood glucose is higher than 240 mg/dL three times in one day - ask for medical assistance.


Davidson PC, et al. Analysis of guidelines for basal-bolus insulin dosing: basal insulin, correction factor, and carbohydrate-to-insulin ratio. Endocr Pract. 2008; 14(9):1095-101.

Johnston JA, Van Horn ER. The effects of correction insulin and basal insulin on inpatient glycemic control. Medsurg Nurs. 2011;20(4):187-193.

Bergenstal RM, Johnson M, Powers MA, Wynne A, Vlajnic A, Hollander P, Rendell M. Adjust to target in type 2 diabetes: comparison of a simple algorithm with carbohydrate counting for adjustment of mealtime insulin glulisine. Diabetes Care. 2008; 31(7):1305-10.

Specialty: Endocrinology

Article By: Denise Nedea

Published On: June 24, 2020 · 12:00 AM

Last Checked: June 24, 2020

Next Review: June 24, 2025