Enter the number of errors observed and the number of opportunities for errors into the Medication Error Rate Calculator. The calculator will evaluate the Medication Error Rate.

## Medication Error Rate Formula

The following two example problems outline the steps and information needed to calculate the Medication Error Rate.

MER = #E / #O * 100

• Where MER is the Medication Error Rate (%)
• #E is the number of errors observed
• #O is the number of opportunities for errors

## How to Calculate Medication Error Rate?

The following example problems outline how to calculate Medication Error Rate.

Example Problem #1:

1. First, determine the number of errors observed.
• The number of errors observed is given as: 40.
2. Next, determine the number of opportunities for errors.
• The number of opportunities for errors is provided as: 1000.
3. Finally, calculate the Medication Error Rate using the equation above:

MER = #E / #O * 100

The values provided above are inserted into the equation below and computed.

MER = 40 / 1000 * 100 = 4.00 (%)

Example Problem #2:

For this problem, the variables required are provided below:

number of errors observed = 60

number of opportunities for errors = 500