METHOD:
FORMULA
Calculation of IV Drip Rate Using Gravity Flow
The physician orders 1 liter of D5 W over 12 hours
(83 mL/hr)
Drop factor 12 drops = 1 mL
Formula: Flow rate drops/minute
Volume in mL/h X drop factor
= Flow rate in drops per minute
60 minutes/h
83 X 12
=
996
= 16.6 or 17 drops per minute
60
60
In summary, 17 drops per minute will deliver 83 mL per hour.

17
METHOD: FORMULA
IV FLOW RATES FOR PIGGYBACK MEDICATION PER
GRAVITY.
The patient is to receive Zincef 1 g in 50 mL D5W over 30
minutes
Formula:
Volume in mL X drop factor
= Flow rate in drops/minute
Time in minutes
50 mL X 15 gtts
=
750
= 25 gtts per minute
30 minutes
30
In summary, 25 gtts per min will deliver 50 mL D5W over 30
minutes.
METHOD FORMULA:
Calculating The Infusion Time
EX. 1000 mL of D5W is to infuse at 125 mL/hour. How
many hours will it take for this liter of fluid to be
completed?
Formula for Infusion Time
Total volume to infuse
= Infusion time (h)
mL/h
1000 mL
=
8 hours
125 mL/h
In summary, 1000 mL at 125 mL/hour will take 8 hours.