IV Drip Rate Calculator
Calculate IV drip rate in drops per minute from volume, time, and drop factor.
Drip Rate
drops per minute (gtt/min)
Flow Rate
milliliters per hour (mL/hr)
The IV Drip Rate Formula
The drip rate determines how many drops per minute (gtt/min) must fall in the drip chamber to deliver a prescribed volume of fluid over a set period of time using a gravity infusion set. It depends on the total volume, the infusion time, and the calibration of the IV tubing (the drop factor).
Drip rate (gtt/min) = (Volume in mL × Drop factor in gtt/mL) ÷ Time in minutes
Flow rate (mL/hr) = Volume in mL ÷ (Time in minutes ÷ 60)
For example, to infuse 1000 mL over 8 hours (480 minutes) using tubing with a drop factor of 15 gtt/mL: (1000 × 15) ÷ 480 ≈ 31 gtt/min, which corresponds to a flow rate of 125 mL/hr. The result is rounded to the nearest whole drop because partial drops cannot be delivered.
Macrodrip vs. Microdrip Drop Factors
The drop factor (also called the drip factor) is the number of drops that make up one milliliter of fluid for a particular IV administration set. It is printed on the tubing package. Sets are broadly divided into macrodrip and microdrip tubing.
Macrodrip (10, 15, 20 gtt/mL)
Macrodrip sets deliver larger drops and are used when fluids must be given quickly, such as for fluid resuscitation, blood products, or general maintenance fluids in adults. Common calibrations are 10, 15, and 20 gtt/mL.
Microdrip (60 gtt/mL)
Microdrip (or minidrip) sets deliver much smaller drops, calibrated at 60 gtt/mL. They are used when precise, low-volume control is required, such as in pediatric, neonatal, or critical-care settings. With microdrip tubing, the drip rate in gtt/min equals the flow rate in mL/hr.
mL/hr vs. gtt/min
Two different units describe the same infusion. The flow rate in mL/hr is the volume delivered each hour and is independent of the tubing used; it is the value typically programmed into an electronic infusion pump. The drip rate in gtt/min is the number of drops counted per minute in the drip chamber and is what you regulate manually with a roller clamp on a gravity set.
Converting between them requires the drop factor: gtt/min = mL/hr × drop factor ÷ 60. When using an infusion pump you generally set mL/hr, while a gravity drip requires you to convert to gtt/min and count drops to verify the rate.
Important: This calculator is provided for educational purposes only and does not constitute medical advice. It does not replace clinical judgment, prescriber orders, or your institution's protocols. Always verify calculations independently and follow your facility's policies and the manufacturer's instructions for the specific IV set in use. Medication and fluid administration must be performed by qualified healthcare professionals.