Lessons · IV drip rate (gtt/min)
Dosage calculation
IV drip rate calculation (gtt/min) When an IV runs by gravity instead of a pump, you count drops per minute. The drip rate depends on the volume, the time in minutes, and the tubing's drop factor (gtt/mL) printed on the package - commonly 10, 15, 20 (macrodrip) or 60 (microdrip).
The formula gtt/min = (Volume mL ÷ Time min) × Drop factor (gtt/mL)
How to solve it Convert the infusion time to minutes. Set up the flow rate (mL ÷ min) and multiply by the drop factor (gtt ÷ mL). Cancel mL so only gtt/min remains, then solve. Round to a whole drop - you cannot count a fraction of a drop. Common mistakes Leaving time in hours instead of converting to minutes. Using the wrong drop factor for the tubing on hand. Reporting a decimal drip rate instead of rounding to whole drops. Safety check: Microdrip tubing (60 gtt/mL) makes gtt/min equal to mL/hr - a useful check, not a shortcut to skip the setup.
Worked examples
See it solved An order reads: infuse 1000 mL of D5 1/2 NS over 12 hours by gravity. The tubing drop factor is 20 gtt/mL.
Volume 1000 mL
Time 12 hr
Drop factor 20 gtt/mL
What is the drip rate in gtt/min?
Answer: 28 gtt/min
Step-by-step solution 1. Start from the flow rate and multiply by the drop factor
( 1000 mL ÷ 720 min ) × ( 20 gtt ÷ 1 mL )
2. Cancel mL and solve
= ( 1000 × 20 ) ÷ 720 gtt/min
= 27.78 gtt/min
3. Round to whole drops (you cannot count part of a drop)
27.78 gtt/min ≈ 28 gtt/min
= 28 gtt/min
An order reads: infuse 1000 mL of lactated Ringer's over 6 hours by gravity. The tubing drop factor is 15 gtt/mL.
Volume 1000 mL
Time 6 hr
Drop factor 15 gtt/mL
What is the drip rate in gtt/min?
Answer: 42 gtt/min
Step-by-step solution 1. Start from the flow rate and multiply by the drop factor
( 1000 mL ÷ 360 min ) × ( 15 gtt ÷ 1 mL )
2. Cancel mL and solve
= ( 1000 × 15 ) ÷ 360 gtt/min
= 41.67 gtt/min
3. Round to whole drops (you cannot count part of a drop)
41.67 gtt/min ≈ 42 gtt/min
= 42 gtt/min
An order reads: infuse 500 mL of D5W over 6 hours by gravity. The tubing drop factor is 10 gtt/mL.
Volume 500 mL
Time 6 hr
Drop factor 10 gtt/mL
What is the drip rate in gtt/min?
Answer: 14 gtt/min
Step-by-step solution 1. Start from the flow rate and multiply by the drop factor
( 500 mL ÷ 360 min ) × ( 10 gtt ÷ 1 mL )
2. Cancel mL and solve
= ( 500 × 10 ) ÷ 360 gtt/min
= 13.89 gtt/min
3. Round to whole drops (you cannot count part of a drop)
13.89 gtt/min ≈ 14 gtt/min
= 14 gtt/min
Safe number notation Every number on DoseDrill is written the safe way - and here is why it matters:
Always use a leading zero for amounts under 1: write 0.5 mg , never .5 mg . A missing zero is read as 5 - a ten-fold overdose.Never use a trailing zero after a decimal: write 5 mg , never 5.0 mg . A stray zero is read as 50 .Read the full safe-notation guide →
Keep going More worked iv drip rate (gtt/min) examples:
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