Insulin Dosage Calculator
HealthEstimate a mealtime insulin dose from carb count and insulin-to-carb ratio, plus a correction dose from current and target glucose. Educational use only.
Educational estimate only. This is not medical advice. Always follow your prescribed insulin regimen and consult your diabetes care team before adjusting doses.
Current Blood Glucose
mg/dL
40600
Target Blood Glucose
mg/dL
70200
Carbohydrates in Meal
g
0300
Insulin-to-Carb Ratio
g/unit
150
Correction Factor (ISF)
mg/dL per unit
10150
Total Estimated Dose
0units
Meal Dose
0 u
Correction
0 u
Guidance
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What is a Insulin Dosage?
An Insulin Dosage Calculator estimates a mealtime (bolus) insulin dose by combining two components used in standard carbohydrate-counting diabetes education: a meal dose based on the carbohydrates you're about to eat and your insulin-to-carb ratio, and a correction dose based on how far your current blood glucose is from your target. The two are added together into a single estimated total dose.
This calculator applies the widely taught ADA/ADCES-style bolus calculation pattern, rounding results to the nearest 0.5 unit to reflect typical pen and syringe precision. It works alongside the Warsaw Method Calculator for high-fat, high-protein meals that need extended dosing beyond standard carb counting, and the Glycemic Load Calculator for evaluating how specific foods may affect post-meal glucose.
How to use this Insulin Dosage calculator
- Enter your Current Blood Glucose reading in mg/dL.
- Enter your Target Blood Glucose — the glucose level you're aiming for, as set by your care team.
- Enter the Carbohydrates in Meal you plan to eat, in grams.
- Enter your prescribed Insulin-to-Carb Ratio (grams of carbohydrate covered per unit of insulin).
- Enter your prescribed Correction Factor (expected mg/dL drop per unit of insulin), then review the Total Estimated Dose, Meal Dose, and Correction Dose, along with the Guidance message — always confirm any real dosing decision with your diabetes care team.
Formula & Methodology
Meal Dose = Carbohydrate grams ÷ Insulin-to-Carb Ratio Correction Dose = (Current Glucose − Target Glucose) ÷ Correction Factor Total Dose = Meal Dose + Correction Dose (rounded to the nearest 0.5 unit; set to 0 with a hypoglycemia warning if current glucose is below 70 mg/dL) This reflects the standard carbohydrate-counting bolus method taught in diabetes education (ADA/ADCES pattern). Worked example: current glucose 180 mg/dL, target 120 mg/dL, 60 g carbohydrate, insulin-to-carb ratio 1:10, correction factor 50 mg/dL per unit: - Meal dose = 60 ÷ 10 = 6 units - Correction dose = (180 − 120) ÷ 50 = 1.2 units, rounded to 1.0 unit - Total estimated dose = 6 + 1 = 7 units
Frequently Asked Questions
This calculator estimates a mealtime insulin dose using two components commonly taught in diabetes education: a meal (carb) dose based on carbohydrate intake and your insulin-to-carb ratio, and a correction dose based on how far your current glucose is from your target. The two are combined into a total estimated dose, rounded to the nearest 0.5 unit.
An insulin-to-carb ratio (ICR) describes how many grams of carbohydrate one unit of rapid-acting insulin covers — for example, a ratio of 1:10 means 1 unit covers 10 grams of carbohydrate. This ratio is individualized and prescribed by a healthcare provider based on factors like body weight, activity level, and insulin sensitivity.
A correction factor, also called an insulin sensitivity factor (ISF), describes how much one unit of rapid-acting insulin is expected to lower blood glucose — for example, a correction factor of 50 means 1 unit typically lowers glucose by about 50 mg/dL. Like the insulin-to-carb ratio, this value is individualized and prescribed by a healthcare provider.
The correction dose is calculated by subtracting your target blood glucose from your current blood glucose, then dividing that difference by your correction factor. If current glucose is below target, the correction dose is negative, effectively reducing the total recommended dose.
If entered blood glucose is below 70 mg/dL, the calculator flags a low glucose warning and does not recommend an insulin dose, since insulin should not typically be given during hypoglycemia. Treat the low blood glucose first according to your care plan and re-check before considering any insulin dose.
No — this calculator is an educational tool only and should never replace your prescribed insulin regimen, your healthcare provider's guidance, or your own clinical judgment and training. Always follow the specific dosing instructions given by your diabetes care team, and consult them before making any changes to your insulin routine.
This calculator covers standard carbohydrate-based dosing, while the [Warsaw Method Calculator](/warsaw-method-calculator/) addresses the additional insulin and extended bolus timing often needed for meals high in fat and protein, which can raise blood glucose more slowly and for longer. Many people use both approaches together depending on what they're eating.
Most insulin pens and syringes are designed to dose in half-unit or whole-unit increments, so rounding to the nearest 0.5 unit reflects what's actually practical to administer. Insulin pumps may allow finer increments — follow your device's specific dosing capability and your care team's guidance.
Carbohydrate counting is inherently approximate, and small estimation errors are normal — pairing tools like the [Carb Calculator](/carb-calculator/) or [Glycemic Load Calculator](/glycemic-load-calculator/) with practiced portion estimation can improve accuracy over time. Consistent tracking and post-meal glucose checks help refine your carb-counting skills.
No — this calculator is designed specifically for mealtime (bolus) dosing based on carbohydrate intake and correction needs, not for basal or long-acting insulin, which follows a different dosing approach typically set and adjusted by your healthcare provider based on overall glucose patterns.
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