Estimate how many pens/vials to dispense for a given days supply

Enter daily total dose, prescription duration, insulin concentration (units/mL), and container volume (mL). Outputs include exact containers needed and the rounded-up whole containers to dispense.

Inputs

Daily total dose (units/day)

Total daily units (e.g., basal + bolus combined).

Days supply

Common: 7, 14, 30, 90 days.

Insulin concentration (units/mL)

Examples: U-100=100, U-200=200, U-300=300, U-500=500 units/mL.

Container volume (mL per pen/vial)

Common: pens 3 mL; vials 10 mL (verify your product).

Container label (optional)

Used in output text only.

Safety margin (optional, %)

Optional extra to reduce refill gaps (e.g., 5–10%).

Extra units to add (optional)

Optional fixed add-on (e.g., anticipated waste).

Rounding

Dispensing generally requires whole pens/vials.

Tip: Use quick buttons (U-100, 3 mL, 10 mL) to populate common values.

Output

Total units needed (for days supply)

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Units per container

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Exact containers needed

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Containers to dispense (rounded)

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Enter values to calculate.

Copy/paste prescription text (optional)

Verify product, payer rules, and clinical plan. This tool estimates supply only (does not recommend doses).

Notes

This tool is for supply estimation (how many pens/vials). It does not recommend insulin doses.
For pens, some clinicians add a small margin for priming/waste. Use Safety margin (%) or Extra units if desired.
Always confirm the insulin’s labeled concentration and container volume for the specific product being prescribed.