37.5
units/day
18.8
units/day
13.3
g/unit
48
mg/dL/unit
80
mg/dL
4.5
units
1.7
units
6.2
units
6
units
37.5
units/day
18.8
units/day
13.3
g/unit
48
mg/dL/unit
80
mg/dL
4.5
units
1.7
units
6.2
units
6
units
The Insulin Dosage Calculator estimates insulin requirements for people with diabetes, including total daily dose (TDD), basal dose, insulin-to-carb ratio (ICR), correction factor (ISF), and bolus doses for meals and glucose correction. Proper insulin dosing is the cornerstone of glycemic management in type 1 diabetes and insulin-requiring type 2 diabetes.
Insulin dosing follows a systematic approach. The Total Daily Dose (TDD) is typically estimated at 0.5 units per kilogram of body weight per day for average insulin sensitivity, though this varies widely (0.3-1.0+ U/kg/day depending on insulin resistance, type of diabetes, and other factors). The TDD is split approximately 50/50 between basal (long-acting, covering fasting metabolism) and bolus (rapid-acting, covering meals and corrections).
Two critical calculations derive from the TDD. The Insulin-to-Carb Ratio (ICR) uses the 500 Rule: ICR = 500 / TDD. This tells you how many grams of carbohydrate one unit of rapid-acting insulin covers. A TDD of 50 units gives an ICR of 10 (1 unit per 10g carbs). The Insulin Sensitivity Factor (ISF) uses the 1800 Rule (for rapid-acting insulin): ISF = 1800 / TDD. This tells you how much one unit of insulin will lower your blood glucose. A TDD of 50 gives an ISF of 36 mg/dL per unit.
The correction dose addresses elevated blood glucose: Correction = (Current Glucose − Target Glucose) / ISF. The meal dose covers carbohydrate intake: Meal Dose = Carbs / ICR. The total bolus is the sum of correction and meal doses. This calculator implements all of these standard calculations used in clinical diabetes education.
Important Disclaimer: This calculator provides estimates based on standard formulas. Actual insulin requirements are highly individual and must be determined by your endocrinologist or diabetes care team. Factors including insulin resistance, exercise, illness, stress, time of day, and concurrent medications all influence real-world dosing. Never adjust your insulin regimen without medical guidance. Incorrect insulin dosing can cause life-threatening hypoglycemia or dangerous hyperglycemia.
The calculator uses standard clinical insulin dosing formulas:
TDD (weight-based) = Body Weight (kg) × 0.5 U/kg
Basal Dose = TDD × 0.5 (approximately 50% of TDD)
ICR (500 Rule) = 500 / TDD — grams of carbohydrate covered by 1 unit of rapid-acting insulin
ISF (1800 Rule) = 1800 / TDD — mg/dL drop per 1 unit of rapid-acting insulin
Correction Dose = (Current Glucose − Target Glucose) / ISF (only if glucose is above target)
Meal Dose = Carbs (g) / ICR
Total Bolus = Correction Dose + Meal Dose
The 1800 Rule applies to rapid-acting insulin (lispro, aspart, glulisine). For regular insulin, use the 1500 Rule instead.
The TDD provides a starting framework. The basal dose (50% of TDD) covers background glucose production by the liver. The ICR guides meal dosing — count carbohydrates and dose accordingly. The ISF guides correction dosing for high readings. The total bolus (meal + correction) is taken before eating. All these values are starting estimates and must be fine-tuned through glucose monitoring. If you experience frequent lows, doses need reduction. If readings are consistently high, doses may need increase. Always work with your diabetes care team.
Inputs
Results
70 kg patient: TDD=35U, ICR=14.3 g/U, ISF=51.4 mg/dL/U. For 60g carbs with glucose at 220: 4.2U meal + 1.9U correction = 6.1U total bolus.
Inputs
Results
Known TDD of 80U (insulin resistant). ICR=6.3 g/U, ISF=22.5. For 45g carbs with glucose at 180: 7.1U meal + 2.2U correction = 9.4U bolus.
The 500 Rule estimates your insulin-to-carb ratio: ICR = 500 / TDD. If your TDD is 50 units, your ICR is 10, meaning 1 unit of rapid-acting insulin covers 10 grams of carbohydrate. This is a starting point — actual ratios are refined through monitoring.
The 1800 Rule estimates your insulin sensitivity factor: ISF = 1800 / TDD. If your TDD is 50 units, your ISF is 36, meaning 1 unit of rapid-acting insulin lowers your blood sugar by 36 mg/dL. For regular insulin, the 1500 Rule is used instead.
TDD is the total amount of insulin (basal + bolus) used in a day. Weight-based starting dose is 0.5 U/kg/day for average sensitivity. Type 1 patients typically need 0.5-0.8 U/kg/day, while insulin-resistant Type 2 patients may need 1.0+ U/kg/day.
The typical split is 50% basal / 50% bolus. Some patients do better with 40/60 or 60/40 splits. The bolus portion is divided across meals based on carbohydrate content. Basal insulin is given once or twice daily.
Correction insulin is taken when blood glucose is above your target, typically before meals (stacking correction with meal bolus). Avoid correcting high blood sugar more frequently than every 3-4 hours to prevent insulin stacking and hypoglycemia.
Insulin stacking occurs when additional insulin is given before the previous dose has fully acted (rapid-acting insulin lasts 3-5 hours). This leads to excess active insulin and increased hypoglycemia risk. Most insulin pumps track 'insulin on board' to prevent stacking.
Carb counting involves reading nutrition labels, using measuring cups/food scales, and learning common portion sizes. Key sources: grains, fruits, dairy, starchy vegetables, and sugars. Protein and fat have minimal immediate glucose impact but can affect later readings.
Many factors alter insulin sensitivity: weight changes, physical activity level, illness, stress, medications (steroids), puberty, pregnancy, menstrual cycle, and progression of diabetes. Regular insulin dose adjustments are a normal part of diabetes management.
This calculator provides educational estimates based on standard formulas. It should NOT replace individualized medical advice. Actual insulin doses must be determined and adjusted by your diabetes care team based on your complete medical history, current medications, and glucose patterns.
Basal insulin (glargine, detemir, degludec) provides steady background coverage over 12-24+ hours, controlling fasting glucose. Bolus insulin (lispro, aspart, glulisine) is rapid-acting, taken before meals to cover carbohydrate intake and correct high glucose. Both are needed for optimal control in Type 1 diabetes.
Roboculator Team
The Roboculator Team explains calculations, planning tools, and practical formulas in clear language for real-life situations.
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