IV Drip Rate Calculator

Drops per minute = (volume in mL × drop factor in gtt/mL) ÷ time in minutes. For 1000 mL over 8 hours on a 20 gtt/mL set: (1000 × 20) ÷ 480 = 41.7, rounded to 42 drops/min.

gtt/min = (volume × drop factor) ÷ time in minutes. The two things people get wrong are using hours instead of minutes, and assuming the drop factor instead of reading it off the giving set.

mL/hr = total volume in mL ÷ time in hours. 1000 mL over 8 hours is 125 mL/hr. No drop factor is involved, because a volumetric pump measures volume directly rather than counting drops.

The drop factor is how many drops make 1 mL for a particular IV giving set, printed on the set packaging in gtt/mL. Macrodrip sets are 10, 15 or 20 gtt/mL; microdrip sets are 60 gtt/mL.

gtt is short for the Latin guttae, meaning drops. So gtt/min is drops per minute and gtt/mL is drops per millilitre — the drop factor of the set.

Drip rate is the number of drops per minute you count in the drip chamber. Flow rate is the volume delivered per unit time, usually mL/hr. They describe the same infusion in different units, linked by the drop factor.

Use drops per minute when the infusion runs by gravity and you control it with a roller clamp while counting the drip chamber. Use mL/hr when you programme an electronic infusion pump.

Drops per minute = (mL/hr × drop factor) ÷ 60. At 125 mL/hr on a 20 gtt/mL set: (125 × 20) ÷ 60 = 42 drops/min.

mL/hr = (drops per minute × 60) ÷ drop factor. At 42 drops/min on a 20 gtt/mL set: (42 × 60) ÷ 20 = 126 mL/hr.

Because there are 60 drops in a mL and 60 minutes in an hour, the two conversion factors cancel out. On a microdrip set, 80 mL/hr is exactly 80 drops/min — which is why paediatric sets are built this way.

On a 20 gtt/mL set it is 33 drops/min; on a 15 gtt/mL set 25 drops/min; on a 10 gtt/mL set 17 drops/min; on a 60 gtt/mL microdrip set exactly 100 drops/min.

1000 mL over 24 hours is about 42 mL/hr, which is 14 drops/min on a 20 gtt/mL set, 10 on a 15 gtt/mL set, 7 on a 10 gtt/mL set, and 42 on a 60 gtt/mL microdrip set.

A macrodrip set makes large drops — 10, 15 or 20 per mL — and suits routine adult volumes and rapid fluids. A microdrip set makes 60 small drops per mL for precise, low-volume infusions in children and neonates.

You do not choose the drop factor from the calculation — you read it off the set you are holding. Choose the set to suit the infusion: 10 gtt/mL for blood, 15 or 20 gtt/mL for routine adult fluids, 60 gtt/mL for children and low rates.

The nominal values are standard across manufacturers — 10, 15, 20 and 60 gtt/mL — but which of them a given product uses varies by country and by set type. Always read the packaging rather than assuming your usual number.

Blood and blood products are more viscous than crystalloid, so they form larger drops and flow more slowly. A 10 gtt/mL blood set has wider tubing and an in-line filter suited to cellular products.

For routine, non-critical fluids in a stable adult, yes — gravity with a counted drip rate is standard practice worldwide. Use a pump for anything where the exact rate matters clinically: vasopressors, insulin, oxytocin, chemotherapy, paediatric fluids and anything titrated.

Gravity flow depends on the height of the bag above the vein, the position of the limb, venous pressure, cannula size and how full the bag is. All of these change during a shift, so a gravity set must be re-checked at every round.

A burette is a graduated chamber in the line, filled with a limited volume of fluid. It is used in paediatrics so that even a runaway rate can only deliver what is in the chamber — typically no more than two hours of fluid.

Watch the drip chamber with a watch or phone timer and count the drops for a full 60 seconds, adjusting the roller clamp until the count matches your target. If time is short, count for 15 seconds and multiply by 4.

Round to the nearest whole drop, since you cannot count a fraction of one. Rounding always shifts the finish time slightly; for a long or critical infusion, check how far and use a pump if the drift matters.

About one-third to one-half full. Too full and you cannot see individual drops to count; too empty and air can enter the line.

Around 60 drops per minute — one drop per second. Above that, drops merge into a stream and counting becomes unreliable, so switch to a volumetric pump or run the bag wide open and time it instead.

Keep vein open (KVO), also written to keep open (TKO), is a deliberately minimal rate — often 10 to 25 mL/hr — that keeps a cannula patent without giving a meaningful fluid load. Local policy sets the exact figure.

Time in minutes = (volume × drop factor) ÷ drops per minute, or simply volume ÷ mL per hour for a pump. A 1000 mL bag at 125 mL/hr lasts 8 hours.

Subtract the volume already infused from the bag volume, then divide the remainder by the rate. 600 mL left at 120 mL/hr is 5 hours. The "Time remaining" mode on this page does it and gives a finishing clock time.

Work out how many minutes remain until the deadline, then treat the volume left as a new order over that time. Enter the remaining volume and remaining time in the drip rate mode above.

Work out the concentration (drug amount ÷ final bag volume), convert the dose to an hourly amount (dose × weight × 60), then divide: mL/hr = amount per hour ÷ concentration. Noradrenaline 4 mg in 50 mL at 0.1 mcg/kg/min for 70 kg is 5.25 mL/hr.

Because the drug you add takes up space. Adding 20 mL of drug to a 100 mL bag gives 120 mL, making the solution 17% more dilute than the label volume suggests and the calculated rate 17% too low.

It gives a concentration of exactly 1 unit/mL, so the prescribed units per hour and the pump rate in mL/hr are the same number. Removing the conversion removes a whole class of error.

Convert to units per hour by multiplying by 60 and dividing by 1000, then divide by the concentration. 10 units in 500 mL is 0.02 units/mL, and 12 milliunits/min is 0.72 units/hr, so the rate is 36 mL/hr.

Yes, and you should for high-alert drugs. Multiply the rate by the concentration to get the amount per hour, then divide by weight and by 60 for a per-minute dose. Reverse-checking is how most infusion errors are caught.

No. Vasopressors such as noradrenaline are titrated to blood pressure and are unsafe at an uncontrolled rate. They belong on a syringe driver or volumetric pump, through a dedicated line, with the rate independently double-checked.

Use the Holliday–Segar 4-2-1 rule: 4 mL/kg/hr for the first 10 kg, plus 2 mL/kg/hr for the next 10 kg, plus 1 mL/kg/hr for every kilogram above 20. A 15 kg child needs 50 mL/hr.

It is the daily version of the 4-2-1 rule: 100 mL/kg/day for the first 10 kg, 50 mL/kg/day for the next 10 kg, then 20 mL/kg/day above 20 kg. It gives the same volume as 4-2-1 over 24 hours.

Because a child tolerates a much smaller margin of error. A macrodrip set at a slow rate is too coarse to control, whereas a 60 gtt/mL burette or a volumetric pump limits both the rate and the total volume available.

No. It estimates maintenance fluid for a well child and excludes deficits, ongoing losses, resuscitation volumes and conditions such as cardiac or renal disease. Follow local paediatric fluid guidance for anything beyond maintenance.

Leaving the time in hours when the formula needs minutes, which makes the rate 60 times too fast. The giveaway is a routine adult bag calculating to hundreds of drops per minute.

Too fast a rate risks fluid overload — breathlessness, raised jugular venous pressure, crackles, pulmonary oedema — and for drug infusions, dose-related toxicity. Slow or stop the infusion, assess the patient and escalate.

The patient is under-treated: dehydration or electrolyte disturbance persists, antibiotic levels stay sub-therapeutic, and the cannula is more likely to occlude. Recalculate the remaining volume over the remaining time rather than simply speeding the bag up without thought.

For high-alert infusions — insulin, heparin, vasopressors, opioids, chemotherapy, concentrated electrolytes and paediatric infusions — yes. An independent second calculation by another qualified person is standard practice in most hospitals.

At minimum at the start, at every nursing round, at handover, after the patient moves or is repositioned, and whenever a bag is changed. Gravity infusions drift, so a counted rate is only accurate at the moment you count it.

Yes. It is completely free, needs no sign-up, and every calculation runs locally in your browser — no values you type are uploaded, stored or shared.

Once the page has loaded, the calculations run entirely in your browser and continue to work without a connection until you close or reload the tab. There is also a printable bedside chart on this page for use away from a screen.

The arithmetic is exact, but it is only as good as what you enter — and it cannot see your patient, your prescription or your giving set. Use it to check your own calculation, not to replace the prescription or your clinical judgement.

Learn the two formulas, always convert time to minutes first, and memorise a few anchors: 1000 mL over 8 hours is 125 mL/hr; on a 20 gtt/mL set that is about 42 drops/min; a 60 gtt/mL set makes drops/min equal mL/hr. Then sanity-check every answer against those.