Pharmacy

IV Drip Rate Calculator

Calculate IV infusion rate in mL/hr, drops per minute, or total infusion time. Supports macro and micro drip sets, weight-based dosing for vasopressors, and common clinical presets.

3 calculation modes Macro + micro drip PDF export

Common presets:

Normal saline 1L over 8h

125 mL/hr

NS 500mL over 5h

100 mL/hr

250mL IV antibiotic

Over 60 min

100mL IV minibag

Over 30 min

Flow Rate

mL/hr

Enter a valid rate.

Drip Set (drop factor)

Macro drip (10-20 gtts/mL): standard adult infusions. Micro drip (60 gtts/mL): paediatric or low-volume infusions.

IV Rate Result

Results:

Flow Rate

mL / hour

Drip Rate

gtts / min

Infusion Time

hours

IV drip rate formulas

Three formulas cover most clinical needs. The one you use depends on what you know and what you need to find.

What you want	Formula
Drops per minute	gtts/min = (Volume mL × Drop factor) ÷ Time in minutes
mL per hour	mL/hr = Volume mL ÷ Time in hours
Infusion time	Hours = Volume mL ÷ Rate mL/hr
Weight-based rate	mL/hr = (Dose × Weight) ÷ Concentration × conversion factor

Macro vs micro drip sets

Macro drip sets deliver 10, 15, or 20 drops per mL. Use them for most adult infusions running at 50 mL/hr or faster. Micro drip sets (60 gtts/mL) are designed for slow infusions where precision matters more, including paediatric infusions and continuous low-dose drug infusions.

At exactly 60 mL/hr, a 60 gtts/mL set delivers exactly 60 drops per minute, which makes counting easy. That's why they're called micro drip sets rather than just "60 factor."

Related tools

For weight-based dose calculation without concentration, see Weight-Based Dose Calculator. For drug concentration conversion (mg/mL to %), see Drug Concentration Converter. For pediatric fluid rates, see Pediatric Fluid Requirement. For volume unit conversion, see Volume Converter. For renal dosing of IV drugs, see Creatinine Clearance.

Safety note: Always double-check IV rate calculations independently before programming an infusion pump. High-alert medications (heparin, insulin, potassium, opioids, vasopressors) require two-nurse verification at the bedside.