IV Infusion & Drip Rate Practice Problems
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IV rate problems come in two flavors: gravity drip rates in drops per minute, and pump rates in mL/hr for weight-based infusions. Drip rate uses the tubing's drop factor; weight-based infusions follow a fixed three-step chain from concentration to dose to pump rate.
Formulasdrops/min = (volume × drops per mL) ÷ time in minutesmL/hr: bag concentration (mcg/mL) → dose (mcg/min) → × 60 → ÷ concentration
Worked exampleInfuse 1,000 mL over 8 hours with a set that gives 15 drops/mL. (1,000 × 15) ÷ (8 × 60) = 15,000 ÷ 480 = 31.25 → 31 drops/min.
Always round drops to a whole number, and round pump rates exactly as the question instructs.
10 IV Infusion & Drip Rate practice problems with worked solutions
Every problem below is worked start to finish. Try it yourself first, then check the steps. For a fresh problem every time, use the practice box above. It generates unlimited variations of these same question types.
Problem 1: IV Drip Rate
An order calls for 200 mL of NS over 3 hours with a set that delivers 60 drops/mL. What is the flow rate in drops per minute? Round your answer to the nearest whole number.
Answer 67 drops/min
Solution- Minutes: 3 hr × 60 min/hr = 180 min.
- Total drops: 200 mL × 60 drops/mL = 12000 drops.
- 12000 drops ÷ 180 min ≈ 66.67 → 67 drops/min.
- Rounded as the question asks: 67 drops/min.
Work in whole drops and whole minutes rather than a decimal mL/min. Carrying a rounded mL/min into the next line is how a correct method produces a wrong number. Drops (gtt) are always whole; you can't give a partial drop.
Problem 2: IV Rate (mL/hr)
Nitroglycerin 100 mg in 250 mL D5W is ordered at 100 mcg/min. What rate in mL/hr should the pump be set at? Round your answer to one decimal place.
Answer 15.0 mL/hr
Solution- Concentration: 100 mg × 1,000 mcg/mg ÷ 250 mL = 400 mcg/mL.
- Dose rate is not weight-based: 100 mcg/min.
- Per hour: 100 mcg/min × 60 min/hr = 6000 mcg/hr.
- Pump rate: 6000 mcg/hr ÷ 400 mcg/mL = 15 mL/hr.
- Rounded as the question asks: 15.0 mL/hr.
The three-step chain (concentration → mcg/min → mL/hr) never changes; only the numbers do. Weight only enters when the order is written per kg. Norepinephrine and nitroglycerin are commonly ordered as a flat mcg/min.
Problem 3: IV Drip Rate
An order calls for 750 mL of NS over 18 hours with a set that delivers 15 drops/mL. What is the flow rate in drops per minute? Round your answer to the nearest whole number.
Answer 10 drops/min
Solution- Minutes: 18 hr × 60 min/hr = 1080 min.
- Total drops: 750 mL × 15 drops/mL = 11250 drops.
- 11250 drops ÷ 1080 min ≈ 10.42 → 10 drops/min.
- Rounded as the question asks: 10 drops/min.
Work in whole drops and whole minutes rather than a decimal mL/min. Carrying a rounded mL/min into the next line is how a correct method produces a wrong number. Drops (gtt) are always whole; you can't give a partial drop.
Problem 4: IV Rate (mL/hr)
Norepinephrine 8 mg in 250 mL D5W is ordered at 6 mcg/min. What rate in mL/hr should the pump be set at? Round your answer to one decimal place.
Answer 11.3 mL/hr
Solution- Concentration: 8 mg × 1,000 mcg/mg ÷ 250 mL = 32 mcg/mL.
- Dose rate is not weight-based: 6 mcg/min.
- Per hour: 6 mcg/min × 60 min/hr = 360 mcg/hr.
- Pump rate: 360 mcg/hr ÷ 32 mcg/mL = 11.25 mL/hr.
- Rounded as the question asks: 11.3 mL/hr.
The three-step chain (concentration → mcg/min → mL/hr) never changes; only the numbers do. Weight only enters when the order is written per kg. Norepinephrine and nitroglycerin are commonly ordered as a flat mcg/min.
Problem 5: IV Drip Rate
An order calls for 200 mL of NS over 1 hours with a set that delivers 20 drops/mL. What is the flow rate in drops per minute? Round your answer to the nearest whole number.
Answer 67 drops/min
Solution- Minutes: 1 hr × 60 min/hr = 60 min.
- Total drops: 200 mL × 20 drops/mL = 4000 drops.
- 4000 drops ÷ 60 min ≈ 66.67 → 67 drops/min.
- Rounded as the question asks: 67 drops/min.
Work in whole drops and whole minutes rather than a decimal mL/min. Carrying a rounded mL/min into the next line is how a correct method produces a wrong number. Drops (gtt) are always whole; you can't give a partial drop.
Problem 6: IV Rate (mL/hr)
Dopamine 800 mg in 250 mL D5W is ordered at 10 mcg/kg/min for a 114 kg patient. What rate in mL/hr should the pump be set at? Round your answer to one decimal place.
Answer 21.4 mL/hr
Solution- Concentration: 800 mg × 1,000 mcg/mg ÷ 250 mL = 3200 mcg/mL.
- Dose rate: 10 mcg/kg/min × 114 kg = 1140 mcg/min.
- Per hour: 1140 mcg/min × 60 min/hr = 68400 mcg/hr.
- Pump rate: 68400 mcg/hr ÷ 3200 mcg/mL = 21.375 mL/hr.
- Rounded as the question asks: 21.4 mL/hr.
The three-step chain (concentration → mcg/min → mL/hr) never changes; only the numbers do. Weight only enters when the order is written per kg. Norepinephrine and nitroglycerin are commonly ordered as a flat mcg/min.
Problem 7: IV Drip Rate
An order calls for 200 mL of NS over 2.5 hours with a set that delivers 12 drops/mL. What is the flow rate in drops per minute? Round your answer to the nearest whole number.
Answer 16 drops/min
Solution- Minutes: 2.5 hr × 60 min/hr = 150 min.
- Total drops: 200 mL × 12 drops/mL = 2400 drops.
- 2400 drops ÷ 150 min = 16 → 16 drops/min.
- Rounded as the question asks: 16 drops/min.
Work in whole drops and whole minutes rather than a decimal mL/min. Carrying a rounded mL/min into the next line is how a correct method produces a wrong number. Drops (gtt) are always whole; you can't give a partial drop.
Problem 8: IV Rate (mL/hr)
Norepinephrine 4 mg in 250 mL D5W is ordered at 10 mcg/min. What rate in mL/hr should the pump be set at? Round your answer to one decimal place.
Answer 37.5 mL/hr
Solution- Concentration: 4 mg × 1,000 mcg/mg ÷ 250 mL = 16 mcg/mL.
- Dose rate is not weight-based: 10 mcg/min.
- Per hour: 10 mcg/min × 60 min/hr = 600 mcg/hr.
- Pump rate: 600 mcg/hr ÷ 16 mcg/mL = 37.5 mL/hr.
- Rounded as the question asks: 37.5 mL/hr.
The three-step chain (concentration → mcg/min → mL/hr) never changes; only the numbers do. Weight only enters when the order is written per kg. Norepinephrine and nitroglycerin are commonly ordered as a flat mcg/min.
Problem 9: IV Drip Rate
An order calls for 750 mL of NS over 20 hours with a set that delivers 60 drops/mL. What is the flow rate in drops per minute? Round your answer to the nearest whole number.
Answer 38 drops/min
Solution- Minutes: 20 hr × 60 min/hr = 1200 min.
- Total drops: 750 mL × 60 drops/mL = 45000 drops.
- 45000 drops ÷ 1200 min = 37.5 → 38 drops/min.
- Rounded as the question asks: 38 drops/min.
Work in whole drops and whole minutes rather than a decimal mL/min. Carrying a rounded mL/min into the next line is how a correct method produces a wrong number. Drops (gtt) are always whole; you can't give a partial drop.
Problem 10: IV Rate (mL/hr)
Dopamine 400 mg in 250 mL D5W is ordered at 15 mcg/kg/min for a 68 kg patient. What rate in mL/hr should the pump be set at? Round your answer to one decimal place.
Answer 38.3 mL/hr
Solution- Concentration: 400 mg × 1,000 mcg/mg ÷ 250 mL = 1600 mcg/mL.
- Dose rate: 15 mcg/kg/min × 68 kg = 1020 mcg/min.
- Per hour: 1020 mcg/min × 60 min/hr = 61200 mcg/hr.
- Pump rate: 61200 mcg/hr ÷ 1600 mcg/mL = 38.25 mL/hr.
- Rounded as the question asks: 38.3 mL/hr.
The three-step chain (concentration → mcg/min → mL/hr) never changes; only the numbers do. Weight only enters when the order is written per kg. Norepinephrine and nitroglycerin are commonly ordered as a flat mcg/min.
Sources and how far they go
Where a convention on this page comes from a published standard, the standard is named. Where it comes from a textbook or from ordinary practice instead, the entry says so. That difference matters when a preceptor or an exam disagrees with you.
- Administration set labeling (drop factor, gtt/mL). Drop factor is a property of the specific set; it is read off the package, never assumed.
- Practice context, not a citation. ISMP best-practice guidance for hospitals points the other way from this arithmetic: smart infusion pumps with dose error-reduction software, standardised concentrations, and orders written in metric rate units (mL/hour, mcg/kg/min) rather than drops. Counting gtt/min is an examinable skill and a gravity-set fallback. It is not what current guidance wants you doing at the bedside for a high-alert infusion.
- USP General Chapter <1160> Pharmaceutical Calculations in Pharmacy Practice. The one published standard that covers pharmacy calculation method generally.
Citations are to the source of the method. They are not a review of this page, and none of these bodies has reviewed or endorsed it.