Insulin Dosage Calculator · Bolus & Correction

Insulin Dosage Calculator

Calculate bolus insulin based on carbohydrate intake, correction factor, and target glucose.

Diabetes Type
Insulin Parameters
g/U
mg/dL/U
mg/dL
mg/dL
Dosage Results
💉 Total Bolus: — U
🍞 Food Bolus
— U
📈 Correction Bolus
— U
💉 Total Bolus
— U
📊 Status
—
💡 Recommendation
Enter your values and click Calculate to see your insulin dosage.
📋 Calculation Details
Food Bolus = Carbs ÷ ICR  ·  Correction = (Current − Target) ÷ ISF  ·  Total = Food + Correction

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Faiq Ur Rahman

Founder & CEO, Toolraxy

Faiq Ur Rahman is a web designer, digital product developer, and founder of Toolraxy, a growing platform of web-based calculators and utility tools. He specializes in building structured, user-friendly tools focused on health, finance, productivity, and everyday problem-solving.

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What Is Bolus Insulin and Why Is Dosing Important?

Bolus insulin is the rapid-acting insulin taken with meals to manage the glucose rise from food (prandial dose) and to correct high blood sugar (correction dose). Unlike basal insulin, which provides a steady background level of insulin throughout the day, bolus insulin is taken as needed to handle specific glucose challenges. Accurate bolus dosing matters because taking too little results in hyperglycemia (high blood sugar), which over time causes complications like neuropathy, retinopathy, and kidney disease. Taking too much causes hypoglycemia (low blood sugar), which can be immediately dangerous, leading to confusion, seizures, or loss of consciousness. Proper dosing balances these risks by matching insulin delivery to the body’s actual needs.

What is Insulin Dosage Calculator?

The Insulin Dosage Calculator helps individuals with diabetes determine the appropriate bolus insulin dose for meals and glucose correction. Bolus insulin is the fast-acting insulin taken before meals to cover carbohydrate intake and to correct high blood glucose levels. This calculator uses two key parameters, your Insulin-to-Carb Ratio (ICR) and Insulin Sensitivity Factor (ISF) to compute precise dosing recommendations.

For people using multiple daily injections (MDI) or insulin pumps, accurate bolus dosing is essential for maintaining target glucose levels, preventing hyperglycemia, and avoiding hypoglycemia. This tool simplifies the math, providing instant results based on your personalized ratios. Simply enter your ICR, ISF, target glucose, current glucose, and carbs to eat, and the calculator will show your food bolus, correction bolus, and total dose.

How to Use the Insulin Dosage Calculator

  1. Select your diabetes type (Type 1 or Type 2) using the radio buttons.

  2. Enter your Insulin-to-Carb Ratio (ICR) — the grams of carbohydrates covered by 1 unit of insulin.

  3. Enter your Correction Factor (ISF), the mg/dL drop in blood glucose per unit of insulin.

  4. Enter your Target Blood Glucose, your desired blood glucose level.

  5. Enter your Current Blood Glucose, your measured blood glucose level.

  6. Enter the Carbohydrates you plan to eat in grams.

  7. Use the quick example buttons to test common scenarios.

  8. Click Calculate (or wait for automatic updates) to view your dosage.

  9. Review your Food Bolus, Correction Bolus, and Total Bolus.

  10. Read the recommendation for personalized guidance on your dose.

 

How the Insulin Dosage Calculator Formula Works

The calculator computes bolus insulin using two separate components: food bolus and correction bolus. The total bolus is the sum of both components.

Food Bolus Formula:
Food Bolus = Carbohydrates (g) ÷ Insulin-to-Carb Ratio (ICR)

The ICR represents the number of grams of carbohydrates covered by 1 unit of rapid-acting insulin. For example, if your ICR is 10 g/U, you take 1 unit of insulin for every 10 grams of carbohydrates you eat.

Correction Bolus Formula:
Correction Bolus = (Current Glucose − Target Glucose) ÷ Correction Factor (ISF)
(Only applies if Current Glucose > Target Glucose)

The ISF represents the number of mg/dL that 1 unit of insulin will lower your blood glucose. For example, if your ISF is 40 mg/dL/U, 1 unit of insulin will lower your glucose by approximately 40 mg/dL.

Total Bolus Formula:
Total Bolus = Food Bolus + Correction Bolus

The calculator rounds doses to the nearest 0.1 unit for practical insulin administration.

 

Worked Example

Sarah has Type 1 diabetes and uses an insulin pump. Before lunch, she checks her glucose and plans her meal:

Inputs:

  • ICR: 10 g/U

  • ISF: 40 mg/dL/U

  • Target Glucose: 100 mg/dL

  • Current Glucose: 180 mg/dL

  • Carbohydrates: 60 g

Step 1 — Food Bolus:
Food Bolus = 60 ÷ 10 = 6.0 U

Step 2 — Correction Bolus:
Since 180 > 100, Sarah needs a correction.
Correction Bolus = (180 − 100) ÷ 40 = 80 ÷ 40 = 2.0 U

Step 3 — Total Bolus:
Total Bolus = 6.0 + 2.0 = 8.0 U

Recommendation:
“A moderate dose of 8.0 U is recommended. This includes 6.0 U for food and 2.0 U for correction.”

Sarah administers her 8.0 units of rapid-acting insulin, eats her meal, and monitors her glucose to ensure it returns to target range.

Frequently Asked Questions

What is the Insulin Dosage Calculator and how does it work?

The Insulin Dosage Calculator is a tool that estimates bolus insulin doses based on your personal ICR and ISF. It works by computing a food bolus (carbs ÷ ICR) and a correction bolus (if current glucose exceeds target, (current − target) ÷ ISF), then adding them together for the total dose.

 

How accurate is the Insulin Dosage Calculator?

The calculator performs accurate arithmetic based on the values you enter. However, individual insulin responses vary, and the calculator provides estimates that should be confirmed with your healthcare provider. Always monitor your glucose response and adjust dosing as needed.

 

What is an Insulin-to-Carb Ratio (ICR)?

The ICR tells you how many grams of carbohydrates are covered by 1 unit of insulin. For example, an ICR of 10 means 1 unit of insulin covers 10 grams of carbohydrates. The ICR is personalized and determined by your healthcare provider.

 

What is a Correction Factor (ISF)?

The ISF tells you how much 1 unit of insulin will lower your blood glucose in mg/dL. For example, an ISF of 40 means 1 unit of insulin will lower glucose by about 40 mg/dL. The ISF is also personalized and determined by your healthcare provider.

 

What if my blood glucose is below target?

If your current glucose is below target, you should generally avoid giving insulin for correction. Instead, treat hypoglycemia with fast-acting carbohydrates and consider whether a reduced food bolus is needed. The calculator will not generate a negative correction dose.

 

Can I use this calculator for both Type 1 and Type 2 diabetes?

Yes, the calculator works for both Type 1 and Type 2 diabetes. The formulas are the same, though typical ICR and ISF values may differ between types. The diabetes type selection is provided for context and interpretation.

 

What is the “target glucose” and how do I know mine?

Target glucose is the blood glucose level you aim to achieve. For most people with diabetes, pre-meal targets are typically 80–130 mg/dL, and post-meal targets are less than 180 mg/dL. Your individual target is determined by your healthcare provider based on your health history, age, and other factors.

 

Should I round the dose?

Yes, insulin doses are typically rounded to the nearest 0.5 or 1.0 unit depending on your insulin delivery device. The calculator provides results to 0.1 units, and you can round as appropriate.

 

What if my ICR or ISF changes?

ICR and ISF can change over time due to weight changes, activity levels, illness, or other factors. Work with your healthcare provider to regularly reassess and update your ratios.

 

Is this calculator safe for use without healthcare provider guidance?

No. This calculator is intended as an educational tool and should not replace personalized medical advice. Always consult your healthcare provider for insulin dosing decisions, especially when starting or adjusting therapy.

Medical Disclaimer

This Insulin Dosage Calculator is provided for educational and informational purposes only. It does not constitute medical advice, diagnosis, or treatment recommendations. Insulin dosing is a complex medical decision that must be individualized and supervised by a qualified healthcare provider. The results are estimates based on the values you enter, but they should not replace professional medical evaluation, clinical judgment, or personalized care. Always consult with your healthcare provider before making any changes to your insulin regimen. Improper insulin dosing can lead to serious complications including hypoglycemia, hyperglycemia, and diabetic ketoacidosis. No calculator can substitute for proper medical assessment and personalized care.

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