Microdrip Tubing (60 gtt/mL): Why gtt/min Equals mL/hr
Shows the work. Every example is computed with the formula and numbered steps. For study and exam practice, not for patient care.
Microdrip: IV tubing that delivers small drops, 60 drops per mL, used for small volumes and slow, precise rates.
Microdrip tubing has a drop factor of 60 gtt/mL. Its small drops make slow rates easier to regulate, so it is used for small volumes and slow infusions, such as for children.
A shortcut follows from the 60: the drip rate formula multiplies by 60 drops per mL and divides by 60 minutes per hour, and the two cancel. With microdrip tubing, the drops per minute are the same number as the mL per hour.
Infuse 0.45% sodium chloride 500 mL over 10 hours by gravity with microdrip tubing (60 gtt/mL).
- Volume
- 500 mL
- Infusion time
- 600 minutes
- Drop factor
- 60 gtt/mL
Formula gtt/min = volume × drop factor ÷ minutes.
- gtt/min = volume × drop factor ÷ minutes.
- 500 mL × 60 gtt/mL ÷ 600 minutes = 50 gtt/min.
- 50 gtt/min is exact, so no rounding is needed.
Answer 50 gtt/min
Sources
- Clinical Calculations: With Applications to General and Specialty Areas — Elsevier (Kee, Marshall, et al.)
- Calculate with Confidence — Elsevier (Morris)