Plan dosing with carb counting and corrections quickly. Adjust for units, active insulin, and rounding. Always confirm doses with your clinician before injecting insulin.
This tool uses a common educational model that combines a meal dose and a correction dose, then subtracts active insulin:
If you choose mmol/L, glucose and ISF are converted internally using ~18 mg/dL per mmol/L.
| Carbs (g) | ICR (g/u) | Current | Target | ISF | IOB (u) | Rounding | Estimated bolus (u) |
|---|---|---|---|---|---|---|---|
| 45 | 12 | 180 mg/dL | 110 mg/dL | 40 | 0.5 | 0.5 | 6.0 |
| 60 | 10 | 140 mg/dL | 100 mg/dL | 50 | 0 | 1 | 7 |
| 30 | 15 | 9.5 mmol/L | 6.0 mmol/L | 2.5 | 0.3 | 0.5 | 3.0 |
| 50 | 11 | 65 mg/dL | 110 mg/dL | 45 | 0 | 0.5 | 0 (low glucose safety) |
A bolus estimate blends meal insulin with a glucose correction. This calculator separates each piece, then recombines them, so you can see what drives the final number and catch input errors quickly. An optional percentage adjustment can model plan‑based changes for exercise, stress, or illness when your clinician has defined a rule.
Meal insulin is based on net carbohydrates: total carbs, plus any adjustment, minus any fiber you subtract per your plan. Net carbs are divided by your insulin‑to‑carb ratio (ICR), expressed as grams covered by one unit. A 60 g meal with an ICR of 10 g/unit yields 6.0 units before other changes.
Correction insulin estimates how far current glucose sits above the target, divided by the insulin sensitivity factor (ISF). ISF is the expected drop from one unit in your chosen unit system. If glucose is 180 mg/dL, target is 110 mg/dL, and ISF is 40 mg/dL per unit, the correction is (180−110)/40 = 1.75 units. When mmol/L is selected, values are converted internally using ~18 mg/dL per mmol/L.
Insulin on board (IOB) is subtracted to reduce stacking, which can raise hypoglycemia risk. The calculator treats IOB as a direct subtraction from the combined meal and correction total. Because devices and care plans estimate IOB differently, enter the value that matches your device method and timing. If meal plus correction is 7.0 units and IOB is 0.5, the raw total becomes 6.5 units.
Many pens dose in 0.5 or 1.0 unit steps, while pumps may support finer increments. The rounding setting applies after adjustments and safety caps, aligning the estimate with what you can deliver. An optional maximum bolus cap can prevent unusually large outputs from displaying without review. CSV and PDF exports support logging and follow‑up discussions.
The breakdown helps you validate reasonableness: meal dose scales with carbs, and correction shrinks as glucose approaches target. If current glucose is low (below 70 mg/dL or 3.9 mmol/L), this tool suppresses dosing outputs to prioritize safety. Very high readings may require a sick‑day plan. Always confirm numbers with your meter, device guidance, and clinician instructions.
No. It provides an educational estimate based on inputs you enter. Insulin dosing is individualized and can be dangerous. Use only a clinician‑approved plan and follow your device instructions.
ICR links carbohydrates to meal insulin. ISF links glucose difference to correction insulin. Both are personal settings typically provided by your clinician and may vary by time of day.
If your current glucose is below 70 mg/dL (3.9 mmol/L), the calculator suppresses bolus outputs and shows a safety warning. Follow your hypoglycemia treatment plan and recheck glucose before considering insulin.
Select mmol/L to enter glucose and ISF in mmol/L units. The calculator converts internally using about 18 mg/dL per mmol/L, then applies the same meal and correction formulas.
IOB is subtracted from the combined meal and correction dose to reduce stacking. Use the IOB value from your pump/pen app or your clinician’s method so the subtraction reflects insulin still active.
Pick the smallest dose step your device can deliver, such as 0.5 units for many pens. Rounding occurs after adjustments and caps, so the final recommendation matches what you can physically dose.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.