IV Drip Rate Formula
mL/hr and drops per minute explained
Designed for UK clinical practice.
Overview
How IV drip rates are calculated
IV drip rates can be expressed as mL per hour (mL/hr) or drops per minute (gtt/min). These calculations help estimate infusion delivery rates when setting pumps or running gravity infusions.
Formula
Standard formulas
mL/hr = total volume (mL) ÷ time (hours)
drops/min = (volume × drop factor) ÷ time (minutes)
Worked example
Example calculation
1000 mL over 8 hours:
mL/hr = 1000 ÷ 8 = 125 mL/hr
Using a 20 gtt/mL giving set:
drops/min = (1000 × 20) ÷ 480 = 41.6 ≈ 42 drops/min
Clinical safety
Reference and cross-check only. IV infusion rates must always be verified against the prescription, infusion pump settings, patient condition, and local policy before administration.
Reference
View clinical reference sourceTool
Open IV Drip Rate Calculator