IV flow rate and drip rate calculator
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Result
For exam practice only. This is a study aid, never a clinical decision: always follow the prescription, local protocols and the product information.
Work out the IV flow rate in mL/h for an infusion pump and the drip rate in drops per minute (gtt/min) for a gravity infusion. Enter the volume, the time and the drop factor printed on the tubing package, and every step of the calculation is shown, as in nursing dosage calculation exams.
Step-by-step solution
Pump rate
Drip rate
Key formulas
- Pump rate
- mL/h = volume (mL)/time (h)
- Drip rate
- drops/min = volume (mL) × drop factor / time (min)
- Infusion time
- time (h) = volume (mL)/rate (mL/h)
How to calculate an IV drip rate
- Flow rate for an infusion pump: mL/h = volume (mL) ÷ time (h).
- Drip rate for a gravity infusion: gtt/min = volume (mL) × drop factor (gtt/mL) ÷ time (min).
- Convert the time to minutes first: 8 h = 480 min. Example: 1000 mL over 8 h with a 20 gtt/mL set gives 1000 × 20 ÷ 480 = 41.7, so 42 gtt/min.
- Round the drip rate to a whole drop, because you can only count whole drops. Round the pump rate as the pump allows, usually to tenths or whole mL/h.
Questions and answers
What does gtt or gtts mean?
gtt is short for the Latin gutta, a drop; gtts (guttae) means drops. In an IV calculation, gtt/min means drops per minute and gtt/mL is the drop factor: how many drops make 1 mL in that giving set.
What do the other IV abbreviations mean?
mL/h (also written mL/hr) is millilitres per hour, the rate set on an infusion pump. DF is the drop factor in gtt/mL. KVO or TKO (keep vein open, to keep open) is a very slow rate that only keeps the cannula open. NS is normal saline (0.9% sodium chloride) and D5W is 5% dextrose in water.
What is the difference between macrodrip and microdrip?
Macrodrip sets give large drops, usually 10, 15 or 20 gtt/mL, and are used for adults and faster rates. Microdrip sets give 60 gtt/mL and are used for children and slow or precise rates. With a microdrip set the drip rate in gtt/min equals the flow rate in mL/h.
Is there a shortcut for the drip rate?
Yes: divide the flow rate in mL/h by the drop factor constant, which is 60 ÷ drop factor. The constant is 6 for 10 gtt/mL, 4 for 15 gtt/mL, 3 for 20 gtt/mL and 1 for 60 gtt/mL. Example: 125 mL/h with a 15 gtt/mL set is 125 ÷ 4 ≈ 31 gtt/min.
How do I round the drip rate?
Round to the nearest whole drop: 41.7 gtt/min becomes 42 gtt/min, because you cannot count part of a drop. If your school or hospital uses a different rounding rule, follow that rule in the exam.
Practise it yourself
Practise IV infusion rates
A calculator gives the answer. In the exam you need the method: practise it with new problems, hints and worked solutions.