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: The tenth place is the first digit after the decimal point, and the hundredth place is the second digit after the decimal point. Refer to Decimals- opens in a new window for detailed information.

number 123.456 with places labelled. 1=hundred, 2=ten, 3=hundred, 4=tenth, 5=hundredth, 6=thousandth

Example:
30 lb = 13.6078 kg
Remember: one decimal place = tenth, two decimal places = hundredth To round 13.6078 to the nearest tenth, we look at the number in the hundredths place. If it is between 5 and 9, we round up by adding 1 to the tenths place. Otherwise, we round down and keep the tenths place unchanged. Since the digit in the hundredths place is 0, we round down and get 13.6.
Solution:	30 lb = 13.6 kg

Example:

30 lb = 13.6078 kg

Remember: one decimal place = tenth, two decimal places = hundredth

To round 13.6078 to the nearest tenth, we look at the number in the hundredths place. If it is between 5 and 9, we round up by adding 1 to the tenths place. Otherwise, we round down and keep the tenths place unchanged.

Since the digit in the hundredths place is 0, we round down and get 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 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

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 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

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.

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

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. There is a 9 in the ones place, so when we round up, it becomes 10. This means we write 0 in the ones place and add 1 to the tens place. As a result, we end up with 250.

Example 2:

249.71 mL/hr

Rounded to:

250 mL/hr

Note: We need to round 249.71 to a whole number. There is a 9 in the ones place, so when we round up, it becomes 10. This means we write 0 in the ones place and add 1 to the tens place. As a result, we end up with 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 25, 2025 4:00 PM
URL: https://tlp-lpa.ca/math-tutorials
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Math: Basic Tutorials

Math: Basic Tutorials : General Dosage Rounding Rules

General Dosage Rounding Rules

Rounding rules for:

Weight, Fluid Oral Volume & Temperature

Tablets & Capsules

Fluid Injectable Volume

Intravenous

Practice