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Dosage Calcs

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IV Drip Rate Calculator

Find the gravity drip rate in drops per minute (gtt/min) from the volume, the time, and the drop factor of the tubing.

IV Drip Rate Calculator

Volume (mL) × Drop factor (gtt/mL) ÷ Time (min) = gtt/min

The ordered volume.

Unit: mL

Hours are converted to minutes.

Use the number printed on the IV tubing package.

Calculated in your browser. Values are not saved or sent anywhere.

Gravity drip rate

Enter the volume, the time, and the tubing's drop factor, then select Calculate.

Example: 250 mL × 20 gtt/mL ÷ 120 min ≈ 41.67 → 42 gtt/min

Educational Use & Safety

Educational and calculation use only. Dosage Calcs performs mathematical calculations using the values you enter. It does not determine whether a medication, dose, route, frequency, concentration, or infusion rate is appropriate or safe for a patient. Always verify medication orders, calculations, product labeling, and applicable clinical or institutional policies before medication administration. When in doubt, consult an appropriate licensed healthcare professional or pharmacist.

Educational Use & Safety

Educational use: You supply the volume, time, and drop factor. This tool does not decide how fast any fluid or medication should run. Learn more.

What this calculates

When an infusion runs by gravity, the rate is set by counting drops in the drip chamber. The drip rate tells you how many drops should fall each minute.

Formula and inputs

Volume (mL) × Drop factor (gtt/mL) ÷ Time (min) = gtt/min

  • Volume — the amount to infuse, in mL.
  • Time — in minutes. If you enter hours, the calculator multiplies by 60 first.
  • Drop factor — how many drops make 1 mL with this tubing.

The mL cancel, leaving drops divided by minutes.

Drop factor

The drop factor is printed on the IV tubing package. Common values in coursework are 10, 12, 15, and 20 gtt/mL (often called macrodrip) and 60 gtt/mL (microdrip). No single value is correct for every set, so always use the number on the package you actually have. Choose "Other" to type the value from your package.

Worked examples

Example 1: microdrip tubing

500 mL over 4 hours, 60 gtt/mL.

4 hr × 60 = 240 min

500 mL × 60 gtt/mL ÷ 240 min = 125 gtt/min

Example 2: a result that needs rounding

250 mL over 2 hours, 20 gtt/mL.

2 hr × 60 = 120 min

250 mL × 20 gtt/mL ÷ 120 min = 5,000 gtt ÷ 120 min ≈ 41.67 gtt/min

Rounded to whole drops: 42 gtt/min

Example 3: from an mL/hr rate

A rate of 75 mL/hr means 75 mL in 60 minutes. With 15 gtt/mL tubing:

75 mL × 15 gtt/mL ÷ 60 min = 18.75 → 19 gtt/min

Example 4: time in minutes

100 mL × 10 gtt/mL ÷ 30 min ≈ 33.33 → 33 gtt/min

Whole-drop rounding

Gravity drip rates are expressed as whole drops per minute because a partial drop cannot be counted. The calculator keeps full precision through every step and rounds only the final gtt/min to the nearest whole drop, showing the unrounded value in the work. This rule applies to drip rates only; the other calculators on this site do not round to whole numbers.

Common mistakes

  • Dividing by hours instead of minutes. Convert hours to minutes first.
  • Using a remembered drop factor instead of the one on the tubing package.
  • Rounding in the middle of the problem instead of at the end.
  • Confusing gtt/min with mL/hr. With 60 gtt/mL tubing they happen to be the same number, but not otherwise.

What this tool does not do

It does not know any fluid or drug and does not suggest rates. It only calculates from the numbers you enter.

FAQ

Why is 60 gtt/mL tubing a shortcut?

With 60 drops per mL and 60 minutes per hour, the drops per minute equal the mL per hour.

What if my tubing lists a different drop factor?

Choose Other and enter the value printed on the package. The calculator accepts any positive number and still rounds the final rate to whole drops.

I use a pump. Which calculator do I need?

Pumps use mL/hr. Use the IV flow rate calculator.

Sources

Formulas, units, and terminology were checked against these open references. Wording on this page is our own.

All sources · How we build and test calculators