How to Measure the Open Rate and Open Factor in Email Marketing
Published on 2 July 2014 | Author Stefan von Lieven0
The precondition that an email can unfold its potentials in email marketing, is that the email is actually delivered to the users and subsequently opened. In this article you will learn how to track opens correctly.
When a user opens an email, this is called “open”. Opens are identified by loading an invisible image when the images in an email are retrieved (tracking pixel). The measurement of opens is not 100 % exact. Users, who have not downloaded images, e.g. because the emails were read in text format, can only be captured indirectly. We can assume that with a click on a link, an open must have happened at the same time. When a user clicks in an email, for which no open has been registered, yet, this open can be included. Modern email marketing solutions do this automatically. In theory, we could use the number of indirectly identified opens and the click rate to calculate how many users opened the email without clicking.
We distinguish between total opens and unique opens. Total opens show the number of all opens. This also includes repeated opens by the same person. When an individual user opens an email more than once, those opens are counted. Unique opens refer to the number of users, who have opened an email at least once. When a user opens an email more than once, only the first open is counted.
The open rate can be calculated as gross or net rate. In the gross calculation, the number of opens is placed in a ratio with the dispatch quantity. In the net calculation, the delivery quantity is included. The open rate shows the percentage of how many sent or delivered emails have been opened.
Gross open rate = opens / dispatch quantity * 100
Net open rate = opens / delivery quantity * 100
Some users open newsletters more than once. The open factor is the ratio between unique opens and total opens. The open factor indicates how often a once opened newsletter was reopened on average.
A higher open factor shows great interest by the reader, as the content is read several times. This is often the case, when the email is used as a point of entry, e.g. for a login.
Open Factor = total opens / unique opens
Other Email Marketing Performance Figures
Other important performance figures to measure success in email marketing can be found in our checklist The 25 Most Important Email Marketing Performance Figures