Insulin Dose Calculator
Estimate your total daily insulin dose, carb ratio, sensitivity factor, and correction dose — for educational purposes only.
💉 Insulin Dose Calculator
Estimated Results
Total Daily Dose estimate
units/day
units/day
g carbs per unit
mg/dL per unit
How to Use the Insulin Dose Calculator
Enter Your Weight
Type your body weight and toggle between kg and lbs — the calculator converts automatically without losing your entry.
Choose Diabetes Type
Type 1 uses 0.5 u/kg; insulin-naïve Type 2 uses a conservative 0.2 u/kg starting estimate per ADA guidance.
Select Insulin Type
Rapid-acting analogs (lispro, aspart, glulisine) use the 1800 Rule for ISF. Regular insulin uses the 1500 Rule.
Add Blood Glucose (Optional)
Enter your current reading and target BG in mg/dL or mmol/L to generate a correction dose estimate as well.
Review the Formula
Every result shows the exact calculation — your numbers, the formula, the output — so you can verify and share it.
Discuss With Your Team
Copy the result and bring it to your next appointment. Your provider will confirm, adjust, or explain differences based on your history.
How the Insulin Dose Calculator Works
This calculator applies four published formulas in sequence, using your weight and diabetes type as inputs. Each formula is from peer-reviewed literature cited by the American Diabetes Association.
Step 1 — Total Daily Dose (TDD)
Type 1: 0.5 u/kg/day (midpoint of ADA's 0.4–0.6 range). Insulin-naïve Type 2: 0.2 u/kg/day (conservative start). The basal and bolus components each receive ~50% of TDD as a starting split.
Step 2 — Insulin-to-Carb Ratio (500 Rule)
Result = grams of carbohydrate covered by 1 unit of rapid-acting insulin. A TDD of 40 gives ICR = 12.5g/unit. Meal bolus = carbs ÷ ICR. The 450 Rule is an alternative for some regimens.
Step 3 — Insulin Sensitivity Factor (1800 or 1500 Rule)
Result = mg/dL blood glucose drops per 1 unit. ISF tells you how much to correct per unit of correction insulin.
Step 4 — Correction Dose
Rounded to the nearest 0.5 unit. Note: this does not subtract insulin on board (IOB) from recent doses — a factor clinical pump calculators account for. Always check IOB before correcting.
These formulas produce starting-point estimates. Real-world dosing is determined through titration — adjusting based on actual blood glucose patterns over days and weeks. Individual variation is substantial.
Why This Calculator Is Reliable
Cited Clinical Formulas
TDD, ICR, and ISF formulas are from published sources cited in ADA Standards of Care. Sources listed below.
Full Calculation Shown
Every result displays the formula with your specific numbers — verify the math or share it with your provider.
Zero Data Collection
All computation happens in your browser. No health data is transmitted or stored anywhere.
Plausibility Warnings
Unusual inputs (very high weight, extreme BG values) trigger soft warnings before displaying results.
Safety Notes & Limitations
- Formulas assume adult physiology — do not apply to children without specialist input.
- Pregnancy significantly alters insulin requirements — use the pregnancy-specific calculator and consult your OB/GYN.
- Renal impairment reduces insulin clearance — standard formulas may significantly overestimate needs.
- This calculator does not model insulin on board (IOB) — subtract active insulin before correcting.
- Dawn phenomenon, illness, exercise, and hormonal changes all shift results in ways no formula captures.
Sources & References
- American Diabetes Association. Standards of Medical Care in Diabetes — 2024. Section 9: Pharmacologic Approaches. Link
- Walsh J, Roberts R, Bailey T. "Guidelines for Optimal Bolus Calculator Settings in Adults." J Diabetes Sci Technol. 2011;5(1):129–135.
- Davidson PC et al. "Analysis of guidelines for basal-bolus insulin dosing." Endocr Pract. 2008;14(9):1095–1101.
- NIDDK. Insulin, Medicines, & Other Diabetes Treatments. Link
Last reviewed: June 2025
Frequently Asked Questions
How do I calculate my insulin dose from my weight?
Multiply your weight in kilograms by 0.4–0.6 units to estimate your total daily dose. Most adults start at the midpoint: 0.5 u/kg. A 75 kg person estimates TDD = 75 × 0.5 = 37.5 units/day, split roughly as ~19 units basal and ~19 units bolus pool. Always confirm with your doctor before acting on this estimate — actual needs differ based on your specific physiology and regimen.
What is the difference between basal and bolus insulin?
Basal insulin (long-acting) is taken once or twice daily to maintain stable blood glucose between meals and overnight. Bolus insulin (rapid-acting) is taken at mealtimes to cover carbohydrates eaten, and as a correction when blood glucose is above target. A common starting split is approximately 50% of TDD as basal and 50% as bolus pool. Your endocrinologist will individualise this ratio based on your glucose patterns.
What is the 1800 Rule for insulin?
The 1800 Rule estimates insulin sensitivity factor (ISF) for rapid-acting analogs: ISF = 1800 ÷ TDD. The result is how many mg/dL blood glucose drops per unit. If TDD = 40, ISF ≈ 45 mg/dL per unit. The 1500 Rule applies the same logic to Regular (human) insulin. Use ISF to calculate correction doses: (current BG − target BG) ÷ ISF = correction units needed.
How accurate is a weight-based insulin dose calculator?
Weight-based formulas are population-level starting points — clinically useful for initiating therapy but not precise for any individual. Studies show meaningful variation: the same formula applied to two people of identical weight may produce an estimate that is accurate for one and significantly off for the other. Individual titration against real blood glucose data is always required. These tools are best used to understand the math and prepare for provider conversations.
What should my blood glucose target be for correction doses?
The ADA recommends 80–130 mg/dL (4.4–7.2 mmol/L) before meals for most non-pregnant adults with diabetes. This calculator defaults to 100 mg/dL as an illustrative mid-range value. Individual targets depend on age, hypoglycemia risk, comorbidities, and patient preference. Pregnant individuals have tighter targets (typically 70–95 mg/dL fasting). Your diabetes care team will set your personal target range.