Calculate days supply after rounding to a whole package: insulin pen boxes, inhalers, eye-drop bottles, cream tubes, GLP-1 cartons, and vials.
Enter the quantity dispensed and how much the patient uses per day. The calculator converts the sig into daily use, then divides the dispensed amount to give days supply with the full worked math.
This calculator uses the same training math as the Insulin vials & pens calculator and sits on the all dosage-form day supply tools. Compare Lantus insulin days supply or Fiasp insulin calculator. See all free tools or practice on the pharmacy technician math quiz.
A Lantus SoloStar pen is 3 mL of U-100 insulin (300 units). At 20 units a day, one pen is 15 days. A five-pen carton is 1,500 units, which is 75 days. Two pens would be 30 days only if two pens were dispensed. Days supply follows the package in hand, then floors a partial day. The same step applies to an inhaler canister, an eye-drop bottle, a cream tube, a GLP-1 carton, and a vial.
No. Days supply follows the quantity dispensed. A whole carton uses the carton. Rounding up without dispensing the extra package invents days.
Divide the total quantity dispensed by the amount the patient uses per day. The hard part is converting the sig into a daily amount first: milliliters per day, puffs per day, drops per day, units per day, or grams per day.
Yes. Every Allied Health Academy pharmacy tool is free to use, with no account required, and shows the step-by-step math so you can check your own work.
These tools are built for pharmacy technician training and exam practice. Always verify the result against the prescription, the product label, and your pharmacist before billing a claim.
For educational purposes only — consult the pharmacist or prescriber. This tool computes days supply from the quantity and directions you enter. It does not recommend doses, diagnose, or determine insurance eligibility.
These calculators are free. If you are studying for the PTCB exam, we also publish paid study products and a PharmD-led certification program. Founders pricing is $499 through December 2026.