## Calculating IV Fluid Infusion Rates for Fluids with Gravity Feed Infusion Sets

**When you need to calculate the number of drops per minute for an I.V. infusion rate, you need to know the following information:**

- Prescription giving volume of fluid to be infused and time over which it is to be given. e.g. 1 litre of 0.9% Sodium Chloride over 8 hours.
- If you are using a gravity feed infusion set you will need to know the number of drops which make up 1 ml. This is written on the packaging.

N.B. normally 20 macrodrops = 1ml crystalloid e.g. 20 drops of HO = 1ml and 15 macrodrops = 1ml colloid

**Then simply calculate the following;**

- The number of ml to be given per minute.
- Multiply this figure by the number of drops in 1ml.

e.g. For 1 litre of 0.9% Sodium Chloride over 8 hours:

2.08ml/min x 20 drops/ml = 41.6 drops per minute

This is closest to **42 drops per minute** so you would run the infusion at a 42 drops per minute rate.