# Insulin Dose Calculator

Calculate insulin correction and meal bolus doses. Enter blood glucose, target, correction factor, carbs, and ICR for educational insulin dose estimation.

## What this calculates

Calculate insulin correction and meal bolus doses using your prescribed correction factor and insulin-to-carb ratio. This educational tool demonstrates the standard formulas used in diabetes management for rapid-acting insulin dosing.

## Inputs

- **Current Blood Glucose** (mg/dL) — min 20, max 600 — Your current blood glucose meter reading
- **Target Blood Glucose** (mg/dL) — min 60, max 200 — Your target blood glucose (set by your doctor)
- **Correction Factor (ISF)** (mg/dL per unit) — min 5, max 200 — How much 1 unit of insulin lowers your blood glucose (from your doctor)
- **Carbs to Eat** (g) — min 0, max 500 — Grams of carbohydrates you are about to eat
- **Insulin-to-Carb Ratio (ICR)** (g per unit) — min 1, max 50 — Grams of carbs covered by 1 unit of insulin (from your doctor)

## Outputs

- **Correction Dose** — Insulin to bring blood glucose to target
- **Meal Dose** — Insulin to cover carbohydrates in your meal
- **Total Dose** — Total insulin dose (correction + meal)
- **Calculation Breakdown** — formatted as text — Step-by-step explanation of the calculation
- **CRITICAL WARNING** — formatted as text — Medical safety warning

## Details

Insulin dosing for mealtime management involves two components: a correction dose to bring elevated blood glucose toward target, and a meal dose to cover carbohydrates being consumed. The correction dose is calculated by dividing the difference between current and target blood glucose by the correction factor (also called insulin sensitivity factor or ISF). The meal dose divides the grams of carbohydrates by the insulin-to-carb ratio.

These ratios are individualized and prescribed by an endocrinologist or diabetes care team. Common starting correction factors range from 25-50 mg/dL per unit, and insulin-to-carb ratios from 5-20 grams per unit, but these vary widely based on body weight, insulin resistance, time of day, and individual physiology. Many patients use different ratios for different meals.

CRITICAL DISCLAIMER: This calculator is for educational purposes only. Insulin is a dangerous medication when dosed incorrectly. Too much insulin causes hypoglycemia, which can lead to seizures, loss of consciousness, and death. Too little insulin causes hyperglycemia and potential diabetic ketoacidosis. NEVER use this calculator as a substitute for the guidance of your healthcare provider. Only use correction factors and insulin-to-carb ratios that have been prescribed specifically for you.

## Frequently Asked Questions

**Q: What is a correction factor / insulin sensitivity factor?**

A: The correction factor (also called insulin sensitivity factor or ISF) tells you how much one unit of rapid-acting insulin will lower your blood glucose. For example, a correction factor of 50 means 1 unit of insulin will lower your blood glucose by approximately 50 mg/dL. This number is determined by your endocrinologist based on your total daily insulin dose and individual response. A common starting estimate uses the '1800 rule': 1800 divided by your total daily insulin dose = approximate correction factor.

**Q: What is an insulin-to-carb ratio?**

A: The insulin-to-carb ratio (ICR or I:C) tells you how many grams of carbohydrates one unit of rapid-acting insulin will cover. An ICR of 10 means 1 unit covers 10 grams of carbs. This ratio is individualized and may differ by meal (many people need more insulin per carb at breakfast due to the dawn phenomenon). A common starting estimate uses the '500 rule': 500 divided by your total daily insulin dose = approximate ICR.

**Q: What should I do if my blood glucose is below target before a meal?**

A: If your blood glucose is below your target, the correction dose should be zero (you should not take extra insulin to lower it further). Depending on how low it is, you may want to reduce the meal dose or consume additional carbohydrates. If blood glucose is below 70 mg/dL, treat the hypoglycemia first with 15 grams of fast-acting carbs, wait 15 minutes, recheck, and then proceed with your meal and reduced insulin dose. Always follow your doctor's hypoglycemia protocol.

**Q: Why might my actual insulin needs differ from the calculator?**

A: Insulin sensitivity varies throughout the day (lower in the morning due to dawn phenomenon), with exercise (increased sensitivity for hours after), illness (increased resistance), stress (increased resistance), menstrual cycle, and many other factors. This calculator provides a static estimate based on your prescribed ratios but cannot account for these dynamic variables. Continuous glucose monitors (CGMs) and insulin pumps with algorithms provide more responsive dosing adjustments.

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Source: https://vastcalc.com/calculators/health/insulin-dosage
Category: Health & Fitness
Last updated: 2026-04-21