Example: Humulin 70-30 insulin (10 mL), "Inject 20 units subcutaneously three times daily"
Dispense #2 vials (20 mL total)
20 mL × 100 units/mL = 2000 units20 units × 3 times/day = 60 units/day2000 units ÷ 60 units/day = 33.3 → 33 DOS
Important: Always follow manufacturer in-use (opened) guidelines. Example: Lantus vials have a 28-day in-use limit, even if calculated DOS is higher.
🎓 Supplemental Training — Insulin Vials
Step 1 of 3
Step 1: Calculate total units from the vial(s)
Humulin 70-30 (U-100) — 2 vials of 10 mL each.
2 vials × 10 mL × 100 units/mL = 2000 total units
Multiply total mL dispensed by concentration to get total units available.
Step 2: Calculate daily units
"Inject 20 units TID" = 3 doses per day.
20 units × 3 doses = 60 units/day
Multiply prescribed dose by frequency per day.
Step 3: Calculate DOS
2000 units ÷ 60 units/day = 33.3 → 33 DOS
Divide total units by units per day, then round DOWN. Also check 28-day in-use cap if applicable.
Full Worked Example — Humulin 70-30
Rx: Humulin 70-30 10 mL vial × 2 (20 mL total)
Directions: Inject 20 units subcutaneously three times daily
Total units = 2 × 10 mL × 100 units/mL = 2000 unitsUnits/day = 20 units × 3 doses = 60 units/dayDOS = 2000 ÷ 60 = 33.3 → 33 DOS
⚠️ 33 DOS is within the 28-day in-use cap — verify manufacturer guidelines.
Step 1 of 3
Step 1: Calculate total units from the vial
Lantus (U-100) — 1 vial × 10 mL.
1 vial × 10 mL × 100 units/mL = 1000 units
Standard U-100 insulin: 100 units per mL.
Step 2: Calculate daily units
100 units QD (once daily).
100 × 1 = 100 units/day
QD = once daily.
Step 3: Calculate DOS (with in-use cap)
1000 ÷ 100 = 10 days, BUT Lantus has 28-day in-use cap. Calculated DOS (10) < 28 → Final DOS = 10
Use the lesser of calculated DOS and in-use cap. In this case the calculated DOS is shorter, so we use 10.
Full Worked Example — Lantus 100 units QD
Rx: Lantus 10 mL vial × 1
Directions: Inject 100 units subcutaneously once daily
Total units = 1 × 10 mL × 100 units/mL = 1000 unitsUnits/day = 100 × 1 = 100 units/dayRaw DOS = 1000 ÷ 100 = 10 daysIn-use cap = 28 days → min(10, 28) = Final DOS = 10
✅ Calculated DOS (10) is less than the 28-day in-use cap — use 10 days.
📊 DOS Formula — Animated Infographic
Total Units in Vial(s)÷Units Used Per Day=Raw DOS→Final DOS
Hover over each chip for details. Click Animate to highlight calculated values.
📹 Video Coming Soon — Insulin Vial DOS Walkthrough
🧮 Live DOS Calculator — Insulin Vials
① Total units in vial(s)
Total mL × concentration (units/mL) = total units available