How to calculate IV flow rates:
Intravenous fluid must be given at a specific rate, neither too fast nor too slow. The specific rate may be measured as ml/hour, L/hour or drops/min. To control or adjust the flow rate only drops per minute are used.
The burette contains a needle or plastic dropper which gives the number of drops per ml (the drop factor). A number of different drop factors are available (determined by the length and diameter of the needle).
Common drop factors are:
10 drops/ml (blood set), 15 drops / ml (regular set), 60 drops / ml (microdrop).
To measure the rate we must know:
(a) the number of drops
(b) time in minutes.
The formula for working out flow rates is:
(ml) X drop factor (gtts / ml)
= gtts /
1500 ml IV Saline is ordered over 12 hours. Using a drop factor of 15 drops / ml, how many drops per minute need to be delivered?
X 15 (gttss / ml)
= 31 gtts / minute