Insulin Sensitivity Factor (1800 / 1500 Rule), Carb Ratio (500 Rule) & Bolus Calculator

Compute 1800-Rule ISF, 500-Rule Carb Ratio, and meal + high-glucose correction bolus.

Total Suggested Meal + Correction Bolus
7.28 units
Insulin Sensitivity Factor (1800 ÷ TDD) 40 mg/dL per U
Insulin-to-Carb Ratio (500 ÷ TDD) 11.11 g carbs per U
High-Glucose Correction Portion 1.88 units
Inputs
⚡ Scenarios:
units/day
Total Daily Dose (TDD) of basal + bolus insulin in units/day.
grams
Carbohydrates in the upcoming meal (grams).
mg/dL
Current pre-meal blood glucose (mg/dL).
mg/dL
Target blood glucose (mg/dL).
Results & Graph
Total Suggested Meal + Correction Bolus
7.28 units
Insulin Sensitivity Factor (1800 ÷ TDD)
40 mg/dL per U
Insulin-to-Carb Ratio (500 ÷ TDD)
11.11 g carbs per U
High-Glucose Correction Portion
1.88 units

Total Suggested Meal + Correction Bolus

Graph 1 • Insulin ISF (1800) & ICR (500) • Domain Architecture & Live Telemetry Maps Total Daily Insulin Dose Units, Meal Carbohydrates Grams, Current Blood Glucose Mg Dl through Insulin ISF (1800) & ICR (500) Formula.
Insulin ISF (1800) & ICR (500) • Clinical & Physiological Reference Scale Low / Baseline Target / Reference Elevated / Watch High / Action Total Suggested Meal + Correction Bolus: 7.28 units Insulin Sensitivity Factor 40 mg/dL per U Insulin-to-Carb Ratio (500 11.11 g carbs per U High-Glucose Correction Po 1.88 units
Graph 2 • Total Suggested Meal + Correction Bolus Across Total Daily Insulin Dose Units Sweep (40% → 160%) Evaluates ISF = 1800 / TDD; ICR = 500 / TDD; TotalBolus = (MealCarbs_g / ICR) across 7 operating points (current input highlighted).
0 units 6.40 units 12.80 units 2.91 18 4.37 27 5.82 36 7.28 45 8.73 54 10.18 63 11.64 72
Graph 3 • Joint Sensitivity: Total Daily Insulin Dose Units × Meal Carbohydrates Grams Compares Total Suggested Meal + Correction Bolus when Meal Carbohydrates Grams is shifted +25% (solid) vs. −25% (dashed).
0 units 6.17 units 12.33 units --- Meal Carbohydrates Grams @ 75% 6.04 -30% 7.33 -15% 8.63 +0% 9.92 +15% 11.21 +30%
Summary: At TDD = 45 U/day, ISF (1800 rule) is 1U:40 mg/dL and Carb Ratio (500 rule) is 1U:11.1g, giving 5.4U meal + 1.88U correction = 7.28 units.
Summary: At TDD = 45 U/day, ISF (1800 rule) is 1U:40 mg/dL and Carb Ratio (500 rule) is 1U:11.1g, giving 5.4U meal + 1.88U correction = 7.28 units.
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Formula & Mathematical Methodology: Insulin ISF (1800) & ICR (500) Formula

ISF = 1800 / TDD
ICR = 500 / TDD
TotalBolus = (MealCarbsg / ICR) + max(0, (CurrentBG − TargetBG) / ISF)
ISF = 1800 / TDD; ICR = 500 / TDD; TotalBolus = (MealCarbs_g / ICR) + max(0, (CurrentBG − TargetBG) / ISF)
  • totalDailyInsulinDoseUnits: Total Daily Insulin Dose Units (units/day)
  • mealCarbohydratesGrams: Meal Carbohydrates Grams (grams)
  • currentBloodGlucoseMgDl: Current Blood Glucose Mg Dl (mg/dL)
  • targetBloodGlucoseMgDl: Target Blood Glucose Mg Dl (mg/dL)

Rounding: Clinical scores round to statutory integer or decimal precision; physiological metrics round to 2 decimal places.

Worked Example: Clinical / Physiology Scenario: Insulin ISF (1800) & ICR (500)

Compute 1800-Rule ISF, 500-Rule Carb Ratio, and meal + high-glucose correction bolus.

  1. Enter lab values, anthropometric measurements, or performance test metrics.
  2. Evaluate the reference equation: ISF = 1800 / TDD; ICR = 500 / TDD; TotalBolus = (MealCarbs_g / ICR) + max(0, (CurrentBG − TargetBG) / ISF).
  3. Inspect the primary classification, supporting indices, and 3 SVG charts.
Result: Computes Insulin ISF (1800) & ICR (500) via ISF = 1800 / TDD; ICR = 500 / TDD; TotalBolus = (MealCarbs_g / ICR) + max(0, (CurrentBG − TargetBG) / ISF).

Frequently Asked Questions

How does the Insulin Sensitivity Factor (1800 / 1500 Rule), Carb Ratio (500 Rule) & Bolus Calculator compute its result?

It evaluates ISF = 1800 / TDD; ICR = 500 / TDD; TotalBolus = (MealCarbs_g / ICR) + max(0, (CurrentBG − TargetBG) / ISF) directly in your browser and updates three custom SVG visualizations in real time.

Can I use Goal Seek to solve backwards for a target lab value or pace?

Yes. Click "🎯 Goal Seek" in the results toolbar to solve backwards for any numeric input parameter.

Are my health and biometric inputs kept private?

Yes. All calculations run 100% locally on your device with zero external transmission.

Health & Fitness · Metabolic & Endocrine Health

Insulin Sensitivity Factor (1800 / 1500 Rule), Carb Ratio (500 Rule) & Bolus Calculator: inputs, method, and how to read the result

Compute 1800-Rule ISF, 500-Rule Carb Ratio, and meal + high-glucose correction bolus.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Total Daily Insulin Dose Units: Total Daily Dose (TDD) of basal + bolus insulin in units/day.
  • Meal Carbohydrates Grams: Carbohydrates in the upcoming meal (grams).
  • Current Blood Glucose Mg Dl: Current pre-meal blood glucose (mg/dL).
  • Target Blood Glucose Mg Dl: Target blood glucose (mg/dL).

What the calculation includes

With the default values shown, Total Suggested Meal + Correction Bolus is 7.28 units. The calculation follows Insulin ISF (1800) & ICR (500) Formula; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Total Daily Insulin Dose Units from 45 units/day to 50 units/day changes Total Suggested Meal + Correction Bolus from 7.28 units to 8.08 units. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses peer-reviewed clinical and sports physiology formulas.
  • For educational and informational reference only; clinical scores do not replace physician judgment or laboratory reference ranges.

Scope: Global Clinical & Sports Science Consensus Check the assumptions and limitations against your situation before relying on the estimate.

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