Insulin to Carb Ratio and Correction Factor Calculator
Estimate insulin-to-carb ratio and correction factor from the total daily dose, and a mealtime dose.
Runs in your browser. Your files never leave your device. See how to check
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How to do it
- 1Step 1: Open Insulin to Carb Ratio and Correction Factor Calculator and add your input
Type your numbers or text, add your file, or pick the options you need. Nothing is uploaded: everything stays in your browser.
- 2Step 2: What Insulin to Carb Ratio and Correction Factor Calculator does
Estimate insulin-to-carb ratio and correction factor from the total daily dose, and a mealtime dose.
- 3Step 3: Read the result and compare
The result appears at once. Change one value to see how the answer moves, then keep the figure that fits your case.
- 4Step 4: Copy or save it
Copy the result or download it. For an important decision, confirm it with the official source or an adviser.
About this tool
Enter your total daily insulin dose, the carbohydrates in your meal, your current blood glucose and your target. The calculator uses the 500 rule and 1800 rule to estimate the ratio, the correction factor and a mealtime dose.
Rules of thumb
Insulin-to-carb ratio ≈ 500 ÷ total daily dose (grams of carbohydrate covered by one unit). Correction factor ≈ 1800 ÷ total daily dose (mg/dL lowered by one unit of rapid-acting insulin).
Dose
Meal dose = carbohydrates ÷ ratio. Correction dose = (current glucose − target) ÷ correction factor, if positive. The total is the sum.
Important
These are starting estimates used by diabetes teams to check settings. Your own ratios, active insulin, exercise and illness change the dose. Never use this tool to decide a dose without your clinician's guidance.
For information only. It does not replace a clinician's judgement or local protocols.
Worked example
A total daily dose of 40 units gives a ratio of 1:12.5 g and a correction factor of 1:45 mg/dL. A meal of 60 g carbohydrate and glucose of 180 mg/dL against a target of 110 gives 4.8 + 1.6 = 6.4 units.
Tips for best results
Check every box before you rely on a result, because one wrong digit changes the whole answer. Use the exact figures from your payslip, bill, certificate or contract, and keep a note of the date you calculated. Rates, thresholds and rules change from time to time, so for tax, fees and legal matters treat the output as an estimate and confirm with the official source named on this page. You can run as many scenarios as you like; nothing is saved or sent, and refreshing the page clears the boxes.
Quick facts
- Category: UK & US
- Works in your browser, no sign-up, no upload.
- Your input stays on your device.
- Available in English.
- Content last reviewed:
Frequently asked questions
Are the rules accurate?
They are population averages. Your own settings are set with your team.
Which insulin do they apply to?
Rapid-acting insulin with mg/dL units; mmol/L needs different constants.
What about active insulin?
Subtract insulin still working from earlier doses; the tool does not.
Should I use it to dose?
No, not without your clinician's guidance.