Where do I find the drop factor?

On the giving set packaging. It is the only input here that cannot be guessed, and using the wrong one changes the rate by up to four times.

Health & FitnessclinicalUnited States only

IV Drip Rate Calculator

Gravity infusion drip rate from volume, time and drop factor, with the count over fifteen seconds because that is what a nurse actually does at the bedside.

Also called: drip rate calculator, gtt per minute calculator.

Drip rate

31.3

31.3 drops a minute, which is 125 mL an hour on a 15 gtt/mL set. At the bedside that is 8 drops counted over fifteen seconds, or one every 1.9 seconds. A gravity rate drifts as the bag empties, so it needs rechecking rather than setting once. Enter the drug in the bag to see the delivery rate as well as the fluid rate.

Millilitres per hour

125

Millilitres per minute

2.08

Seconds between drops

1.92

Drops to count in fifteen seconds

7.8

Drug per hour

Micrograms per kilogram per minute

On counting it

At the bedside that is 8 drops counted over fifteen seconds, or one every 1.9 seconds. A gravity rate drifts as the bag empties, so it needs rechecking rather than setting once.

On the drug rate

Enter the drug in the bag to see the delivery rate as well as the fluid rate.

How this is calculated

For reference only. Verify against your clinical protocol before acting on this number.

Method and background

This is what the calculation gives for the numbers you entered. It is an estimate, not advice, and it knows nothing about your situation beyond those numbers. Rules for United States change on a published schedule; the effective date is shown on every rule-based tool.

How this is calculated

The drop factor is printed on the giving set and is the whole conversion: the same fluid over the same time needs four times as many drops on a sixty gtt/mL microdrip set as on a fifteen. Dividing by four gives the count over fifteen seconds, which is how the rate is checked in practice, since counting for a full minute at the bedside is rarely done. Where a drug amount and a weight are entered the page also gives the micrograms per kilogram per minute, which is the unit most infusion protocols are written in.

volume times the drop factor over the minutes available

V: Volume in millilitres
g: Drop factor, drops per millilitre
t: Hours

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

a litre over eight hours

Volume to infuse: 1,000 mL
Over how long: 8 h
Drop factor of the set: Macrodrip, 15 gtt/mL
Drug in the bag: 0 mg
Patient weight: 0 kg

Drip rate31.3

1000 x 15 / 480

Open this example

a microdrip set quadruples the count

Volume to infuse: 1,000 mL
Over how long: 8 h
Drop factor of the set: Microdrip, 60 gtt/mL
Drug in the bag: 0 mg
Patient weight: 0 kg

Drip rate125

boundary: same fluid rate, four times the drops

Open this example

Method and limits

What it assumes

A gravity set, where the rate depends on the roller clamp and the bag height.

What it deliberately does not model

Gravity rates drift as the bag empties and with patient position, so they need rechecking.
An infusion pump is programmed in millilitres per hour and ignores the drop factor entirely.

Formula version 1.0.0 · definition 1.0.0 · United States · Report a problem with this calculator

Frequently asked questions

Where do I find the drop factor?: On the giving set packaging. It is the only input here that cannot be guessed, and using the wrong one changes the rate by up to four times.