Calculate IV gtt/min, mL per hour, and infusion time from volume, time, and drop factor. A 10, 15, 20, and 60 gtt/mL table and worked example are included.
Calculate gravity gtt/min from volume, time, and the drop factor on the administration set. The same inputs give mL/hr. Enter the volume still to infuse when you need time remaining.
Follow facility protocol and the order on the medication administration record. This page shows arithmetic only. It does not choose a rate, a dose, or a product. A nurse or pharmacist confirms the result before anything is given.
Read the calibration printed on the administration set. Macrodrip tubing is commonly marked 10, 15, or 20 gtt/mL. Microdrip tubing is commonly marked 60 gtt/mL.
| gtt/mL | Set | Check |
|---|---|---|
| 10 | Macrodrip | Often printed on a 10 gtt/mL set. Read the package in hand. |
| 15 | Macrodrip | Often printed on a 15 gtt/mL set. Read the package in hand. |
| 20 | Macrodrip | Often printed on a 20 gtt/mL set. Read the package in hand. |
| 60 | Microdrip | Often printed on a 60 gtt/mL set. Read the package in hand. |
gtt/min = (volume in mL × drop factor) ÷ minutes. mL/hr = volume in mL ÷ hours. Time remaining = milliliters left ÷ mL/hr. Round gtt/min to a whole drop because a gravity set cannot count a fraction of a drop. A pump is programmed in mL/hr and does not use the drop factor. Students in nursing, pharmacy technician, and medical programs can use the same arithmetic, then check it against the order and facility protocol.
Multiply the volume in mL by the drop factor in gtt/mL, then divide by the infusion time in minutes. Round to a whole drop for a gravity set because a fraction of a drop is not countable.
mL/hr is volume divided by hours. It does not use the drop factor. gtt/min uses the drop factor printed on the administration set. A pump is set in mL/hr. A gravity set is counted in gtt/min.
Use the number printed on the set: commonly 10, 15, or 20 gtt/mL for macrodrip tubing and 60 gtt/mL for microdrip tubing. Do not guess from the fluid name.
No. It only runs the arithmetic you enter. Follow facility protocol and the medication order. A nurse or pharmacist confirms the rate before it is given.