Email open rate is simply the percentage of emails that your brand's subscribers open.
Here's Jeremy for more:
How Do You Calculate Email Open Rate?
To calculate email open rate, divide the total number of emails you sent by the numbers of emails that were opened. You can also calculate this by dividing the total number of subscribers who have opened an email by the total number of subscribers that email was sent to.
What Is a Good Open Rate for Email?
Daasity has found that DTC eCommerce brands have about a 15% to 20% open rate. However, it is important to realize that open rate tends to decrease with time and/or as your subscriber list grows.
As your subscriber list grows, you will have to segment it in order to send more targeted messaging. While you may maintain a high email open rate with a few thousand subscribers, if you have 100k subscribers, you won't be able to send one-size-fits-all messaging that everyone on that list will want to open.
Why Is Email Open Rate Important?
Tracking email open rate allows you to determine the health of your overall email account. In addition, it gives you a look at how successful your email subject line messaging is: how many people resonate with what you're writing, and how many people are really engaged with your brand.
Maintaining a healthy email open rate is also important because if too many subscribers ignore your emails (i.e., they don't open them), this may cause the email client (Google, Yahoo, etc.) to file your emails in the promotions folder–or even worse, the spam folder.
For content on related metrics, head over here to learn about Email Unsubscribe Rate, and over here to learn about Email Click-Through Rate.