Insulin Dosage Calculator

Created by Joanna Michałowska, PhD candidate
Reviewed by Bogna Szyk and Jack Bowater
Based on research by
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 (July 2008)See 1 more source
Australian Commission on Safety and Quality in Health Care User Guide to the National Subcutaneous Insulin Chart: Acute Facilities (October 2017)
Last updated: Oct 29, 2022

This insulin dosage calculator was created to show you how to calculate insulin dose with as little effort as possible. Your insulin dose regimen should be prescribed by your doctor; however, you may still need to determine your mealtime insulin dose. To do this, you will need to know the carbohydrate content of your meal, your current and target blood glucose, the carbohydrate ratio, and the insulin sensitivity factor. The last two can be easily calculated once the total daily insulin dose is known.

Not sure if you understand all of those phrases? Don't worry! Just read the article below to find out more.

What is insulin?

Insulin is a hormone produced by the pancreas. It allows your body to use the sugar (glucose) that you consume as energy. This hormone is responsible for keeping your blood glucose concentration within the optimal range and prevents both hyperglycemia (too high blood glucose concentration) and hypoglycemia (too low blood glucose concentration).

Both conditions can be really dangerous and are associated with severe health problems, including dizziness, fatigue, loss of consciousness, and even death.

There are several conditions where insulin distribution is disturbed, the most common of which is diabetes.

Treating diabetes with insulin

There are three main types of diabetes:

  • Type 1 – Damage to the pancreatic cells means that little to no insulin is produced.

  • Type 2 – Insulin production is inadequate, or body cells are resistant (fail to respond to insulin), or both.

  • Gestational diabetes – Diabetes that occurs in pregnant women without a prior history of diabetes. Usually disappears after giving birth.

Insulin can be used as a treatment for all three types of diabetes. Insulin is typically given by injection under the skin. Patients with insulin-dependent diabetes usually require some base level of insulin throughout the day (basal insulin), as well as some short-acting insulin to cover meals (bolus insulin).

There are many different types of insulin and just as many different treatment strategies. Which one an individual needs should be established by a doctor.

Among the strategies are conventional insulin therapy, for patients with a regular lifestyle where insulin can be given in regular, fixed doses, and intensive insulin therapy, where the patient decides on their own mealtime insulin dose, which depends on the carbohydrate content of the meal, their current blood sugar concentration, and the amount of physical activity performed.

💡 The amount of insulin can be expressed, e.g., in moles (mol), micrograms (mcg), milligrams (mg), or International Units (IU).

How to calculate insulin dose?

For patients undergoing intensive insulin therapy, their insulin dose regimen is partially prescribed by the doctor, but there are still some calculations that need to be made before establishing the dose of insulin. This insulin dosage calculator provides formulas that allow you to calculate how much bolus insulin you should take for your meal. It helps you to account for the carbohydrate content of your meal and to correct for high blood sugar concentrations.

To do this, you need to know the following information:

  • The carbohydrate content of your meal;

  • The carbohydrate ratio, which tells you how many grams of carbohydrates are covered by one unit of insulin;

  • Your current blood glucose concentration;

  • Your target blood glucose concentration; and

  • The insulin sensitivity factor, which tells you by how many points (mg/dL) one unit of insulin will decrease your blood glucose.

The two elements above that are not in bold can be calculated using your total daily insulin dose.
When you know all the necessary information, your mealtime insulin dose can be calculated in three easy steps:

Step one – carbohydrate coverage

carb. content / carb. ratio = carb. coverage insulin dose

Step two – high blood sugar correction

(current BG - target BG) / ISF = high blood sugar correction insulin dose

Step three – total mealtime insulin dose

carb. coverage insulin dose + high blood sugar correction insulin dose = total mealtime dose

where:

  • carb. – Carbohydrate;

  • BG – Blood glucose; and

  • ISF – Insulin sensitivity factor.

Please note that this calculator will not work if your current blood glucose is below your target blood glucose.

💡 If you're having a hard time controlling the post-meal spikes of blood glucose, try the Warsaw method calculator that accounts for both proteins and fat consumed in your meals.

Total daily insulin dose

The total daily insulin dose is the total amount of insulin taken during one day. It includes both basal and bolus insulin (try saying that 5 times quickly). It can be roughly estimated using simple equations that require your body weight, but your doctor will give you a more accurate number, as it also depends on your body's cells' sensitivity or resistance to insulin.

Carbohydrate coverage

This insulin dosage calculator will help you to calculate your mealtime insulin dose in three easy steps.

First, you need to establish the dose of insulin to cover the carbohydrates in your meal. This amount (in grams) will be divided by the carbohydrate ratio to get the number of insulin units you need. The carbohydrate ratio tells you how many grams of carbohydrates one unit of insulin can deal with. Usually, it's 1 unit per 10-15 grams. Your doctor might have defined it for you; otherwise, it can be easily calculated when the total daily insulin dose is known:

500 / TDID = carbohydrate ratio

where:

  • 500 – Constant used for the initial calculation of the carbohydrate ratio; and

  • TDID – Total daily insulin dose.

Once those calculations are performed, you should know how many units of insulin you need to cover the carbohydrates in your meal.

Do I need to know the carbohydrate content of each meal?

You do need to know the carbohydrate content of your meal to use this calculator. It can be estimated by reading food labels or using tables and guidelines created for diabetic patients. When using the Nutrition Facts panel, you should always look for the total carbohydrate section. Some labels might also have information about the carbohydrate units. One unit is usually 15 grams of carbohydrates (unless stated otherwise).

💡 Note: Some people prefer to use net carbs rather than total carbohydrates for their calculation. Net carbohydrates are what is left when you subtract fiber and sugar alcohols from the total carbs. It is not a term recognized by FDA or the American Diabetes Association. However, if you're interested in low-carb or dietary foods, you might prefer to use this one over the total carbs. This is not medical advice. You should consult every change in your insulin therapy with your leading physician.

High blood sugar correction

In step two, you will account for your current blood glucose concentration. It needs to be measured directly before the meal with your glucose meter. Your doctor should tell you what the target level of your premeal blood glucose is.

Depending on the guidelines, your premeal glucose target may range from 80 to 130 mg/dL. If you measure your blood glucose in mmol/l, you can use our blood sugar converter.

The third value you need to know is the insulin sensitivity factor. Again, it can be determined by your doctor, or you can calculate it when the total daily dose of insulin is known (more information in the next paragraph). The insulin sensitivity factor tells you by how many points (mg/dL) one unit of insulin will decrease your blood glucose.

Insulin sensitivity factor

The insulin sensitivity factor tells you how many points (mg/dL) one unit of insulin will decrease your blood glucose. It can be determined by your doctor or calculated when the total daily insulin dose is known.

1800 / TDID = insulin sensitivity factor,

where:

  • 1800 – Constant used for the initial calculation of the insulin sensitivity factor; and

  • TDID – Total daily insulin dose.

For example:

1800 / 50 units = 36 mg/dL, which means that one unit of insulin decreases blood glucose by 36 mg/dL

Usually, the values for the insulin sensitivity factor range from 30 to 50 mg/dL.

Managing diabetes

Bodies of patients with diabetes either don't produce enough insulin or can't use the insulin as intended. Over time, this can cause serious health problems, such as vision loss and kidney or cardiovascular disease. To check the 10-year risk of cardiovascular disease, visit our CVD risk calculator. Only basic information will be required. You do, however, need to know your cholesterol levels expressed in mg/dl, so the cholesterol units might need to be converted.

Diabetes can't be cured completely, but there are some steps that one can take to reduce the impact of diabetes on their life:

  • Keeping a healthy weight – you can check if your weight is within normal range by calculating your BMI or ideal weight.
  • Eating a healthy diet.
  • Being physically active.

❗ We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace professional medical advice. If anything bothers you or you are unsure how to calculate your insulin dose, consult your doctor.

FAQ

What type of diabetes needs insulin?

For the two types of diabetes:

  • Type I of diabetes is caused by the destruction of insulin islands in the pancreas – the insulin treatment is almost always required.

  • Type II is a result of growing insulin resistance; insulin treatment might be recommended in some cases.

The patients need to start their insulin therapy during a perioperative period or when a high glucose level accompanies the clinical symptoms of diabetes.

How do I calculate the carbohydrate ratio?

Calculating the carbohydrate ratio can be completed in two easy steps:

  1. Compute or write down your Total daily insulin dose.

  2. Follow a simple equation:

    Carbohydrate ratio = 500 / Total daily insulin dose

  3. The typical carbohydrate ratio is 10-15 (per 1 unit of insulin).

How do I calculate insulin sensitivity factor?

To calculate your insulin sensitivity factor, use the following formula:

Insulin sensitivity factor = 1800 / Total daily insulin dose

For example, if your daily insulin dose is 30 units, the calculation would be:

Insulin sensitivity factor = 1800 / 30

Insulin sensitivity factor = 60

Insulin sensitivity factor equals 60 – it means that one unit of insulin decreases blood glucose level by 60 mg/dL.

How to calculate the carbohydrate content of your meal?

The answer is easy – to calculate the carbohydrate content of your meal, you should turn to your food labels.

Look for the total carbohydrate sections and add up all your meal ingredients' carbs.

Joanna Michałowska, PhD candidate
Do you know your total daily insulin dose?
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Step 1 - Carbohydrate coverage
Carbohydrate content
g
Carbohydrate ratio
g
Insulin dose to cover carbohydrates
units
Step 2 - High blood sugar correction
Current blood glucose
mg/dL
Target blood glucose
mg/dL
Insulin sensitivity factor
mg/dL
Insulin dose to correct blood glucose
units
Total mealtime insulin dose
units
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