Drug Calculations

Medication administration is a core competency for nurses in every clinical setting. To safely dispense drugs, nurses must perform accurate drug calculations. New technologies such as bar-coding medication and smart infusion pumps have helped to reduce medication errors, however, nurses cannot rely completely on these advances. Use these resources to fine tune your drug calculation skills and ensure safe medication administration with every dose you give.

Common Drug Calculations 

Two dosage calculation techniques are presented in this free Nursing Pocket Card: traditional formulas and dimensional analysis. Nurses should select one formula and practice to become proficient in that method. This Pocket Card also includes a handy table of dosage calculation conversions.
View and download this FREE  Pocket Card today!

Drug Calculations: How-To Series

How to Use the Universal Formula

In the universal formula – or “desired over have” method – the desired amount is the dose prescribed and the amount you have is the available dose or concentration.  


How To Use Dimensional Analysis

Dimensional analysis – or factor-label method – uses a series of conversion factors of equivalency from one system of measurement to another but doesn’t require memorizing specific formulas. This method reduces errors and can be used for all dosage calculations.


How to Calculate Continuous IV Drips (units/hour)

Dimensional analysis can be used to calculate IV infusions dosed as units/hour.


How to Calculate Continuous IV Drips (mcg/min)

Use dimensional analysis to calculate continuous IV drips dosed as mcg/min.


How to Calculate IV Drips (mcg/kg/minute)

Use dimensional analysis to calculate weight-based continuous IV drips.

How to Calculate Drops Per Minute                  

While continuous IV infusions are typically delivered via infusion pumps, there may be times when an electronic pump is unavailable and calculating the number of drops per minute will be necessary.


More Resources for Drug Calculations

A book with blue pills spilling out of it

Description automatically generatedNursing Drug Handbook

Now in its 44th edition, Nursing2024 Drug Handbook delivers the most current nursing-focused information on more than 3,800 generic, brand-name, and combination drugs.