What is a drop factor?

The drop factor is the number of drops the IV set delivers per mL, printed on the set packaging. Macrodrip sets are usually 10, 15 or 20 gtt/mL and microdrip (paediatric) sets are 60 gtt/mL.

How many drops per minute is 100 mL per hour?

With a 20 gtt/mL set, 100 mL/hour equals about 33 drops per minute. With a 15 gtt/mL set it is 25 drops per minute, and with a 60 gtt/mL microdrip set it is 100 drops per minute.

How do I calculate drops per minute for 500 mL over 8 hours?

500 mL over 8 hours is 480 minutes. With a 20 gtt/mL set: (500 x 20) / 480 = about 21 drops per minute, or 62.5 mL per hour on an infusion pump.

Which IV set drop factor is most common in India?

Most adult macrodrip IV sets sold in India deliver 20 drops per mL. Paediatric and low-volume infusions use a 60 gtt/mL microdrip burette set. Always confirm the value printed on the wrapper.

IV Drip Rate Calculator — Drops per Minute

Infusion Details

Common orders

Total volume (mL)

Infusion time (hours)

Drop factor (printed on the IV set)

Manual drip rate

21 gtt/min

Exact 20.8 · 1 drop every 2.9 s

Pump flow rate

62.5 mL/hr

1.04 mL/min · total 480 min

IV infusion: 500 mL over 8 hours — 62.5 mL/hr, 21 drops/min at 20 gtt/mL (1 drop every 2.9 s)

Disclaimer: This calculator gives an estimate only. Always confirm the drop factor printed on the IV set, count the drip chamber to verify the rate, and follow institutional protocols for critical infusions and paediatric patients.

mL/hour to drops-per-minute chart

Bedside conversion for the four standard drop factors. Values are rounded to the nearest whole drop.

Conversion of infusion flow rate in mL per hour to drops per minute by drop factor
Flow rate	10 gtt/mL	15 gtt/mL	20 gtt/mL	60 gtt/mL
50 mL/hr	8	13	17	50
75 mL/hr	13	19	25	75
100 mL/hr	17	25	33	100
125 mL/hr	21	31	42	125
150 mL/hr	25	38	50	150
200 mL/hr	33	50	67	200

How to set an IV drip rate in 4 steps

1
Note the volume
Read the total volume ordered, e.g. 500 mL normal saline.
2
Note the duration
Convert the ordered duration into hours or minutes.
3
Check the drop factor
Read gtt/mL from the IV set wrapper — 20 for adults, 60 for paeds.
4
Set and count
Adjust the roller clamp, then count the chamber for 15–60 seconds.

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How IV drip rate is calculated

The manual drip rate depends on the IV set's drop factor: drops/min = (volume in mL × drop factor) ÷ time in minutes. For infusion pumps you only need the hourly flow rate: mL/hour = volume in mL ÷ time in hours.

Example: 500 mL of normal saline over 8 hours with a 20 gtt/mL set = (500 × 20) ÷ 480 ≈ 21 drops per minute, or 62.5 mL/hour on a pump.

Common drop factors in India

→ 10 gtt/mL — macrodrip, often blood administration sets
→ 15 gtt/mL — macrodrip
→ 20 gtt/mL — macrodrip, the most common adult set in Indian clinics
→ 60 gtt/mL — microdrip / burette set for paediatric and low-volume infusions

Frequently Asked Questions

What is the IV drip rate formula?

Drops per minute = (volume in mL × drop factor) ÷ infusion time in minutes.

How many drops per minute is 100 mL/hour?

About 33 drops/min with a 20 gtt/mL set, 25 drops/min with a 15 gtt/mL set, and 100 drops/min with a 60 gtt/mL microdrip set.

How do I calculate 500 mL over 8 hours?

480 minutes total. With a 20 gtt/mL set: (500 × 20) ÷ 480 ≈ 21 drops per minute, or 62.5 mL/hour on a pump.

Where do I find the drop factor?

It is printed on the IV administration set wrapper, usually as "20 drops = 1 mL" or "60 gtt/mL".

Should drops per minute be rounded?

Yes — drops cannot be fractional. Round to the nearest whole drop and verify by counting the drip chamber.

Related Free Tools

Reference: intravenous fluid administration principles — NCBI StatPearls: Intravenous Fluid Therapy.

IV Drip Rate & Infusion Calculator