IV Drip Rate Calculator (mL/h, gtt/min and mcg/kg/min)
Work out an IV infusion rate in mL per hour for a pump, drops per minute for gravity tubing with its drop factor, or the pump rate for a weight-based dose in mcg/kg/min, with the dimensional-analysis steps nursing exams expect.
Last updated: October 2026
Pump rate
125 mL/h
Not medical advice. This calculator gives an estimate for general information only. It is not medical advice and does not replace a doctor, pharmacist or other qualified health professional. Always check with them before acting on the result, especially for medication doses, children, pregnancy or a medical condition, and follow the guidelines of your local health authority.
Formula below · 3 sources (fda.gov, registerednursing.org, ismp.org) · Updated Oct 2026
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About this calculator
Three questions come up with every intravenous order, and this calculator answers each with the same dimensional-analysis method that nursing and pharmacy exams use.
1. Pump rate in mL/h: rate = volume (mL) ÷ time (h). An order written in minutes is converted first (mL ÷ min × 60). Infusion pumps are programmed in mL/h, usually to the nearest whole or tenth of a millilitre.
2. Drip rate in drops per minute for gravity tubing: gtt/min = volume (mL) × drop factor (gtt/mL) ÷ time (min). The drop factor is printed on the tubing package: macrodrip sets deliver 10, 15 or 20 drops per mL, microdrip (paediatric or burette) sets 60 drops per mL, so with microdrip the drops per minute equal the mL per hour. Because you cannot count a fraction of a drop, the result is rounded to a whole number; the tile also gives drops per 15 seconds, the usual way to set a roller clamp.
3. Pump rate for a weight-based dose in mcg/kg/min, the form used for vasoactive and sedative infusions (dopamine, dobutamine, norepinephrine, nitroglycerin, propofol): mL/h = dose (mcg/kg/min) × weight (kg) × 60 (min/h) ÷ concentration (mcg/mL), where concentration (mcg/mL) = drug in the bag (mg) × 1,000 ÷ bag volume (mL). The calculator shows the concentration so the units can be checked at each step.
For a dose in mcg/min (no weight), set the weight to 1. For mg/h, convert to mcg/min first (mg/h × 1,000 ÷ 60) or divide the mg/h by the mg/mL concentration directly.
These are arithmetic conversions of an order you already have. The order itself, the concentration, the maximum rate and the patient's response are clinical decisions, and infusions of high-alert drugs are independently double-checked and run on a pump with a drug library. This tool is for study and verification, not for deciding a dose.
Drops per minute for common orders (gtt/min = volume × drop factor ÷ minutes)
Scroll sideways to see all columns →
| Order | mL/h | 10 gtt/mL | 15 gtt/mL | 20 gtt/mL | 60 gtt/mL |
|---|---|---|---|---|---|
| 1,000 mL over 8 h | 125 | 21 | 31 | 42 | 125 |
| 1,000 mL over 10 h | 100 | 17 | 25 | 33 | 100 |
| 1,000 mL over 12 h | 83 | 14 | 21 | 28 | 83 |
| 500 mL over 4 h | 125 | 21 | 31 | 42 | 125 |
| 250 mL over 2 h | 125 | 21 | 31 | 42 | 125 |
| 100 mL over 30 min | 200 | 33 | 50 | 67 | 200 |
| 50 mL over 20 min | 150 | 25 | 38 | 50 | 150 |
| 75 mL/h maintenance | 75 | 13 | 19 | 25 | 75 |
How to use
Pick what you need, then fill in the fields for that mode; the tiles show every rate at once. Example (the defaults): 1,000 mL of normal saline ordered over 8 hours. Pump rate = 1,000 ÷ 8 = 125 mL/h. With 15 gtt/mL tubing: 1,000 mL × 15 gtt/mL ÷ 480 min = 31.25, so set 31 drops per minute, or about 8 drops every 15 seconds. With microdrip (60 gtt/mL) it would be 125 gtt/min. Example, weight-based: dopamine 400 mg in 250 mL ordered at 5 mcg/kg/min for a 70 kg patient. Concentration = 400 mg ÷ 250 mL = 1.6 mg/mL = 1,600 mcg/mL. Dose per minute = 5 × 70 = 350 mcg/min; per hour = 350 × 60 = 21,000 mcg/h. Rate = 21,000 ÷ 1,600 = 13.125, so the pump is set to 13.1 mL/h. Choose "Pump rate in mL/h for a mcg/kg/min dose" to see this as the headline. Example in minutes: an antibiotic in 100 mL to run over 30 minutes with 20 gtt/mL tubing. 100 × 20 ÷ 30 = 66.7, so 67 gtt/min, which equals 200 mL/h on a pump.
Frequently asked questions
What is the formula for drops per minute?
gtt/min = volume in mL × drop factor (gtt/mL) ÷ time in minutes. For 1,000 mL over 8 hours (480 minutes) with 15 gtt/mL tubing: 1,000 × 15 ÷ 480 = 31 drops per minute. Round to a whole drop, since you count drops.
How do I convert mL/h to drops per minute?
Multiply the mL/h by the drop factor and divide by 60: gtt/min = mL/h × gtt/mL ÷ 60. At 125 mL/h, 10 gtt/mL tubing gives 21 gtt/min, 15 gtt/mL gives 31, 20 gtt/mL gives 42 and 60 gtt/mL (microdrip) gives 125, the same number as the mL/h.
What is the drop factor and where do I find it?
The number of drops the tubing produces per millilitre, printed on the package: 10, 15 or 20 gtt/mL for macrodrip sets and 60 gtt/mL for microdrip sets. Macrodrip is used for most adult fluids; microdrip for small volumes, children and when precise low rates are needed without a pump.
How do I calculate mL/h from mcg/kg/min?
Multiply the dose by the weight and by 60 to get mcg per hour, then divide by the concentration in mcg/mL (mg in the bag × 1,000 ÷ mL in the bag). For norepinephrine 4 mg in 250 mL (16 mcg/mL) at 0.1 mcg/kg/min for 80 kg: 0.1 × 80 × 60 = 480 mcg/h ÷ 16 = 30 mL/h.
Should I round the pump rate?
Pumps accept whole mL/h or, on many models, tenths. Follow the policy of your unit: large-volume fluids are set to the nearest whole mL/h, vasoactive and paediatric infusions to the nearest 0.1 mL/h. Never round a drip or pump rate before the final step of the calculation.
Does this work for paediatric fluids?
The arithmetic is the same; what differs is the volume. Use the Holliday-Segar method (our fluid requirements calculator) to find the maintenance volume for the child's weight, then enter it here with the time to get the pump rate, usually with microdrip tubing or a pump.
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Sources & references
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