IV Drip Rate Calculator
Calculate drops per minute (gtt/min) for manual gravity infusions, or mL/hr for electronic pump settings — with manual formula reference for NREMT exam prep.
Part of the EMS Medical Calculator Suite
Quick presets
Tip: 1 hour = 60 min, 8 hours = 480 min
Check your IV tubing package — the drop factor is printed on the label.
IV Formula Reference
Drip Rate
gtt/min = (Volume mL × Drop factor) ÷ Time (min)
Flow Rate
mL/hr = Volume (mL) ÷ Time (hr)
Convert mL/hr → gtt/min
gtt/min = (mL/hr × Drop factor) ÷ 60
Common drop factors: 10 gtt/mL (macrodrip), 15 gtt/mL (macrodrip), 20 gtt/mL (macrodrip), 60 gtt/mL (microdrip). The drop factor is always printed on the IV tubing package.
How to Calculate IV Drip Rates
An IV drip rate tells you how fast a gravity infusion is running — measured in drops per minute (gtt/min). Every manual IV infusion requires calculating this number so you can adjust the roller clamp to deliver the correct fluid volume over the prescribed time. The core formula tested on the NREMT is:
For example: 500 mL ordered over 4 hours (240 minutes), using 15 gtt/mL tubing:
(500 × 15) ÷ 240 = 7,500 ÷ 240 = 31.25 → 31 gtt/min
Flow Rate vs. Drip Rate: What's the Difference?
Flow rate (mL/hr) is the setting for electronic infusion pumps — how many milliliters per hour the pump delivers. It's the simpler calculation: total volume divided by total hours.
Drip rate (gtt/min) is for gravity IV sets where you manually adjust the roller clamp and count the drops falling in the drip chamber. It depends on the drop factor of your IV tubing, which varies by manufacturer and tubing type.
In EMS practice, knowing how to convert between them matters: if your electronic pump fails in the field, you need to calculate the manual drip rate on the fly. The weight-based dose calculator can help when the infusion is a weight-based drip.
Frequently Asked Questions
What does "drop factor" mean on IV tubing?
The drop factor is the number of drops that equal 1 mL of fluid for a specific IV tubing set. Macrodrip tubing (10, 15, or 20 gtt/mL) is used for most adult fluid infusions. Microdrip tubing (60 gtt/mL) is used for precise pediatric or medication infusions. Always read the packaging — never assume the drop factor.
Should I round my drip rate up or down?
Always round to the nearest whole number — you can't count a fraction of a drop. For NREMT exam purposes, round to the nearest whole number unless the question specifies otherwise. In practice, slight rounding is clinically acceptable; reassess and readjust as needed.
How do I manually count drip rate?
Count the drops falling in the drip chamber for 60 seconds. For a faster method, count drops for 15 seconds and multiply by 4. Adjust the roller clamp until the count matches your target gtt/min. Recount after adjusting — it takes practice to get the feel right.
What is a microdrip set used for?
A microdrip (60 gtt/mL) set is used when very precise, low-volume infusions are required — such as pediatric patients or medication infusions where even small variations in delivery rate matter. A useful property: with a 60 gtt/mL set, the drip rate in gtt/min numerically equals the flow rate in mL/hr, making mental math easier.
Do I need to know IV math for the NREMT?
Yes. IV drip rate calculations appear on the NREMT cognitive exam — and calculators are not permitted during the test. You need to be able to solve these problems on scratch paper. Use this tool to check your manual work, not to skip the math. Pair it with the medication dosage calculator for a complete IV and dosing study session.
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