Math: Basic Tutorials : General Dosage Rounding Rules

General Dosage Rounding Rules

When calculating the dosage of medications to be administered, there are occasions when the outcome is not a whole number. Then, nursing dosage rounding rules need to be applied to dosage calculation problems.

Proper rounding ensures accuracy in medication administration and client care. This section covers standard rounding guidelines for weight, fluid oral volume, temperature, tablets/capsules, fluid injectable volume, and intravenous calculations.

Rounding rules for:

Weight, Fluid Oral Volume & Temperature

When converting body weight from lb to kg, round it to the nearest tenth.
For fluid oral volume and temperature, round it to the nearest tenth as well.

Note: tenth stands for the first place after the decimal point. Refer to Decimals- opens in a new window for detailed information.

Example:
30 lb = 13.6078 kg
To round 13.6078 to the nearest tenth, we look at the number on hundredth. If this number is in the range of 5 to 9, we round it up by adding 1 to the tenth. Otherwise, we round it down to keep the tenth unchanged. Since 0 is on hundredth, we round it down to 13.6
Solution:	30 lb = 13.6 kg

Example:

30 lb = 13.6078 kg

To round 13.6078 to the nearest tenth, we look at the number on hundredth. If this number is in the range of 5 to 9, we round it up by adding 1 to the tenth. Otherwise, we round it down to keep the tenth unchanged.

Since 0 is on hundredth, we round it down to 13.6

13.6078 with an arrow labeled 'tenth' pointing at the 6, and an arrow labeled 'hundredth' pointing at the 0

Solution:

30 lb = 13.6 kg

Tablets & Capsules

Round unscored tablets to the nearest whole number.
Scored tablets maybe broken in half, so numbers of scored tablets should be rounded to the nearest half tablet.

Example 1: Unscored
Order: 600 mcg In hand: 250 mcg/tablet Dosage: 2.4 tablets	To round 2.4 to a whole number, we check the number on tenth. Since it is 4 on tenth, round down to 2 tablets.
Solution:	The dosage is 2 tablets
Example 2: Scored
Order: 600 mcg In hand: 250 mcg/tablet Dosage: 2.4 tablets	Since 2.4 is between 2.25 and 2.50, 2.5 is the nearest half. Round it up to 2.5 tablets.

Solution:	The dosage is 2.5 tablets

Fluid Injectable Volume

Round to the nearest hundredth if the volume is less than 1 mL.
Round to the nearest tenth if the volume is greater than 1 mL.

Example 1:
0.345 mL	0.345 is less than 1, so it should be rounded to the nearest hundredth. On thousandth it is a 5, so round it up to 0.35 mL.
Solution:	The dosage is 0.35 mL
Example 2:
1.345 mL	1.345 is greater than 1, so it should be rounded to the nearest tenth. On hundredth it is a 4, so round it down to 1.3 mL.
Solution:	The dosage is 1.3 mL

Intravenous

Round to the nearest whole number for piggyback infusion, such as flow rate in gtt/min or mL/hr, and drop factor in gtt/mL as drops cannot be fractionated.
Round to the nearest tenth for dose -based flow rate such as mg/mL.

Example 1:
15.25 gtt/min	Rounded to:	15 gtt/min
Example 2:
249.71 mL/hr	Rounded to:	250 mL/hr
Note: we need to round 249.71 to a whole number. It is 9 on the place of ones, so when rounding it up we get 10, which means we will write 0 on the place of ones and add one to the place of tens. Therefore we finally got 250.
Example 3:
20.612 gtt/mL	Rounded to:	21 gtt/mL
Example 4:
0.625 mg/mL	Rounded to:	0.6 mg/mL.

Practice

Dosage Rounding Practice Questions

Last Updated: Jun 5, 2025 4:16 PM
URL: https://tlp-lpa.ca/math-tutorials
Print Page

Virtual Help

Math: Basic Tutorials