Drops Per Minute Calculator
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) gtts 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:
- The volume of the desired infusion.
- The planned time of the infusion.
- The drop factor/ calibration - number of guttae (drops in Latin) for every unit of solution.
- That's it! Check the advanced mode button for the number of drops per hour.
Want to know more? Check our other intravenous infusion tools, such as the maintenance fluids for children calculator and the sodium correction for hypo-and hypernatremia calculator.
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
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 =
= 154 mEq/L Na
How to calculate drops per minute with a volume of 500 mL and a time of 60 minutes?
The drops per minute index is 125 drops/minute (with calibration of 15 drops/mL).
To calculate it step by step:
- Check the volume of the infusion (500 mL).
- Define the time at which you want to administer the infusion (60 minutes).
- Define the drop factor (15 drops/mL).
- Use the formula:
Drops per minute
= (Volume × Drop factor) / Time
= (500 × 15) / 60 = 125
How do I calculate the flow rate in drops per minute?
To count the flow rate in drops per minute:
- If you know the flow rate in mL/hour, use the calibration (or drop factor) to calculate drops per minute.
Drops per minute = (Drip rate × Drop factor) / 60
- If you don't know the flow rate, use the volume (in mL) and time (in hours) of the infusion to calculate it:
Drip rate= Total volume / Infusion time
How do I control the drip rate?
To control the drip rate:
- Count the drops in the drip chamber for one minute.
- Use the roller clamp to set the rate.
- Count the drops again to check if everything works out as you want.
You might also encounter electronic flow control devices that calculate everything for you. It's still a good practice always to double-check the outcome.
How do I find the drip rate without the drop factor?
To find the drip rate without the drop factor:
- You'll need the infusion volume (in mL) and the time it must be administered (in hours).
- Now use the formula
Drip rate [mL/h] = Volume / Infusion time
- If you want to convert it to mL/min, divide the result by 60.
Drip rate [mL/min] = Drip rate [mL/h]/60
- Unfortunately, you cannot find the drops per minute value without the drop factor.