Set an IV without a pump by computing drops per minute: volume times the tubing’s drop factor, divided by the time in minutes. A core infusion calculation in one formula.
The example
1000 mL over 480 min, 15 gtt/mL.
| A | B | |
|---|---|---|
| 1 | Item | Value |
| 2 | 1000 mL × 15 | — |
| 3 | ÷ 480 min | → 31 gtt/min |
The formula
The formula:
How it works
How it works:
- Drop factor (gtt/mL) is printed on the IV tubing — commonly 10, 15, 20, or 60 (microdrip).
- Multiply volume × drop factor, then divide by the time in minutes.
ROUND(…, 0)— you can only count whole drops per minute.- For an mL/hr pump rate instead, use
volume_mL / time_hours.
Educational use only. These are general Excel formulas for learning spreadsheet techniques — not medical advice or a substitute for clinical judgment, professional guidelines, or verified dosing references. Always confirm calculations against authoritative sources and institutional protocols.
Try it: interactive demo
Volume (mL), time (min), drop factor.
Variations
Pump rate (mL/hr)
For a pump:
Microdrip (60 gtt/mL)
gtt/min = mL/hr:
Infusion time
From a set rate:
Pitfalls & errors
Time in minutes. The drip-rate formula uses minutes; convert hours first (×60).
Right drop factor. Read it off the tubing — 15 vs 60 changes the answer fourfold.
Round whole drops. You count integer gtt/min.
Practice workbook
Frequently asked questions
How do I calculate IV drip rate in Excel?
What's the drop factor?
How do I get a pump rate in mL/hr instead?
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