Insulin Correction Factor & Sensitivity Calculator
Calculate your Insulin Sensitivity Factor (ISF) and high blood sugar correction bolus using the validated 1800 and 1500 clinical rules.
Calculate Your Correction Factor
Enter your blood glucose reading and insulin information below.
mg/dL
mg/dL
Units per 24 hours
Quick Summary
Estimate how many points (mg/dL or mmol/L) one unit of rapid-acting or regular insulin lowers your blood glucose. Calculate precise correction doses based on current glucose, clinical target glucose, and Total Daily Dose (TDD).
How It Works
- Enter your current blood glucose reading — Use a finger-stick or CGM reading as the starting value for the calculation.
- Set your target blood glucose level — The level your healthcare provider considers your target (for example, 100–130 mg/dL / 5.6–7.2 mmol/L is a common clinical range).
- Enter your total daily dose (TDD) of insulin — The sum of all basal and bolus insulin over a typical 24-hour period.
- Select the appropriate rule — The 1800 Rule (commonly associated with rapid-acting insulin analogs), the 1500 Rule (regular insulin), and additional rules (1600, 1700, 2000, 2200). Discuss with your healthcare provider which rule is appropriate for you.
- Review your results — The calculator displays your insulin sensitivity factor (ISF) and an estimated correction dose rounded to the nearest half-unit.
Formula Used
The Insulin Sensitivity Factor (ISF), also called the correction factor, represents the expected drop in blood glucose (in mg/dL or mmol/L) per unit of insulin. For example, an ISF of 40 mg/dL means one unit of insulin is expected to lower your blood glucose by approximately 40 mg/dL.
The 1800 Rule (ISF = 1800 ÷ TDD) is most commonly used with rapid-acting insulin analogs. The 1500 Rule (ISF = 1500 ÷ TDD) was developed for regular insulin. Additional rules (1600, 1700, 2000, 2200) are also available. All rules provide clinical estimates — individual responses vary and should be discussed with your healthcare provider.
Evidence
The 1800 Rule and 1500 Rule are clinical estimation methods referenced in diabetes education curricula and published clinical practice guidelines. The American Diabetes Association (ADA) Standards of Medical Care in Diabetes discusses insulin dose adjustments, including correction dose calculations, as part of intensive insulin therapy management for both type 1 and type 2 diabetes.
Multiple academic medical centers and clinical guidelines reference these rules:
- The University of Iowa Stead Family Children's Hospital references the 1700 and 1800 Rules in pediatric diabetes education materials, including the formula "Correction Dose = (Current BG − Target BG) / ISF".
- Stanford Medicine adult outpatient insulin guidelines explicitly use the 1800 Rule for calculating correction factors in type 2 diabetes management.
- The American Diabetes Association provides educational resources on insulin correction dosing in its Safe at School program.
These formulas are clinical guidelines, not precise measurements. Actual insulin sensitivity can vary based on time of day, physical activity, illness, stress, menstrual cycle, and other factors. All insulin dosing decisions should be made in consultation with a qualified healthcare provider.
How to Interpret Your Results
Your Insulin Sensitivity Factor (ISF) indicates how much your blood glucose is expected to decrease per unit of insulin. For example:
- ISF of 30 mg/dL/unit — Each unit lowers BG by about 30 mg/dL (lower sensitivity)
- ISF of 50 mg/dL/unit — Each unit lowers BG by about 50 mg/dL (moderate sensitivity)
- ISF of 80+ mg/dL/unit — Each unit lowers BG by about 80 mg/dL (higher sensitivity)
Your estimated correction dose is calculated from the difference between your current and target blood glucose divided by your ISF. The result is rounded to the nearest half-unit, the typical increment for most insulin pens and syringes. This is an educational estimate — your actual dosing needs may differ.
Important considerations: The correction dose calculation does not account for recent insulin activity, physical activity, carbohydrate intake, illness, or individual response patterns. These factors can affect insulin sensitivity and should be discussed with your healthcare provider.
The ISF and correction dose are estimates based on the selected rule and your entered values. Actual blood glucose response to insulin varies based on many factors. If your measured blood glucose does not align with the estimate, consult your healthcare provider.
When to consult your healthcare provider: The calculator provides educational estimates. Any questions about your insulin dosing, blood glucose patterns, or changes in your estimated correction factor should be discussed with your healthcare provider.
Medical Disclaimer
The information provided by Qurekit's calculators is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or treatment. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
Frequently Asked Questions
Medical References
- American Diabetes Association — Standards of Care in Diabetes
- University of Iowa Stead Family Children's Hospital — Correction Factors and Ketone Corrections
- American Diabetes Association — Safe at School: Insulin Dose Correction Case Study (2023)
- Stanford Medicine — Type 2 Diabetes Adult Outpatient Insulin Guidelines
- National Institutes of Health (NIH) — Insulin Therapy in Type 1 Diabetes
Related Tools
Version History
Every version is logged with its build date, changes, and evidence sources so you can verify the methodology.
Version v1.0.0
Initial Implementation
Initial implementation of the Correction Factor (Insulin Sensitivity) Calculator. Implements the 1800 Rule and 1500 Rule along with additional clinical rules (1700, 2000, 2200) for estimating insulin sensitivity factor and correction doses. Built on evidence-based diabetes education curricula from leading medical institutions. Internal BG values normalized to mg/dL for consistent cross-unit calculation.
Changes
- Initial calculator implementation
- 1800 Rule and 1500 Rule calculation engine
- Additional rules: 1700, 2000, 2200
- Bidirectional unit conversion (mg/dL / mmol/L) with internal mg/dL normalization
- ISF display always shown in the user's selected unit
- Educational interpretation of results
- Safety warnings for hypoglycemia and severe hyperglycemia
- Medical references section with authoritative sources
- FAQ section with 7 evidence-based questions
- Structured data (WebApplication, MedicalWebPage, FAQPage)
- BreadcrumbList JSON-LD for SEO
- Accessibility: keyboard navigation, aria-live, focus management
- Mobile-responsive layout
- Related tools carousel
Evidence Sources
- American Diabetes Association
- University of Iowa Stead Family Children's Hospital
- Stanford Medicine
- DiabetesSisters