Drops Per Minute Calculator

Created by Łucja Zaborowska, MD, PhD candidate
Reviewed by Bogna Szyk and Jack Bowater
Based on research by
University of South Australia Drops per minute (DPM) - WorksheetSee 1 more source
Wilson, K.M. The nurse’s quick guide to I.V. drug calculations Nursing Made Incredibly Easy! (2013)
Last updated: Mar 12, 2022

This drops per minute calculator allows you to painlessly calculate the number of drops per minute needed for a given intravenous therapy. Our tool comes as handy in all types of drip calculations: we'll help you find the volume, time, and the drop factor value.

Take a look at the text below to discover the drop factor equation, (guttae) ggts per minute formula and tips on how to calculate the drip rate per minute or hour. 💧

How to use the drops per minute calculator?

To calculate the flow rate in drops per minute, you'll need to input the following data:

  1. The volume of the desired infusion.
  2. The planned time of the infusion.
  3. The drop factor/ calibration - number of guttae (drops in Latin) for every unit of solution.
  4. That's it! Check the advanced mode button for the number of drops per hour.

Check our other intravenous infusion tools:

How to calculate drops per minute?

It's not as difficult as it seems! Try the following drops per minute formula:

Drops per minute = (Volume * Drop factor) / (Time)

💡 The gtts per minute formula uses the metric system.

  • Volume should be given in milliliters (mL).
  • Drop factor uses the unit of gtt per minute (drops per minute).
  • Time must be given in minutes.

Since you can already answer the question "How to calculate drops per minute?", Let's focus on how to calculate the drops per hour ratio.

Drops per hour = (Volume * Drop factor) / (Time / 60)

How to calculate drop factor?

The value of drop factor should be printed on the package of the IV set of your choice. Different solutions have different properties and use various drip factor formulas.

Always use IV sets that correspond to your needs! Choose micro- or macrodrip tubing.

  • Microtubing - 60 gtt/min, especially useful in pediatrics and drugs with narrow tolerance range; and
  • Macrotubing - 10-20 gtt/min.

💡 The bigger the drop factor, the slower the infusion rate.

The drop factor formula is, in fact, a modified version of the equation presented above:

Drop factor = (Drops per minute * Time) / Volume

Drip rate

The most straightforward formula for the drip rate is as follows:

Drip rate (mL/hour) = Total volume (mL) / Infusion time

However, the drip rate can also be calculated using the drop rate formula (this function is available in the advanced mode of our gtt in min calculator):

Drip rate = Drops per hour / Drop factor,


Drip rate = (Drops per minute * 60) / Drop factor

It is crucial to set the drip rate very carefully! Even seemingly safe substances can have a potentially lethal effect on your patients - even the well-known and commonly used NaCl solution can lead to encephalopathy, seizures, and tetraplegia (paralysis of all four limbs). This effect is seen in patients with low sodium levels when the infusion rate is too fast.

The correction rate in hyponatremia should not exceed 6-12 mEq/L in the first 24 hours, and 18 mEq/L or less over 48 hours.

Regular saline = 0.9% NaCl = 154 mEq/L Na

You may also try our sodium deficit and sodium correction tools!

Łucja Zaborowska, MD, PhD candidate
Drop factor
Drops per minute
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