Click-to-Open Rate (CTOR)


Apple’s Mail Privacy Protection Initiative which is included with iOS 15 and is expected sometime in the fall of 2021 will impact Open Rate, Click-to-Open Rate, Open Reach Rate, and Render Rate for users reading mail on Apple Mail. The information here may change and we will update it when we know more. To learn more visit the Only Influencers Pixelgeddon Resources Page.

Click-to-open Rates (CTOR) are between 0% and 100%; once you finish the equation, turn your answer to a percentage by multiplying by 100. CTOR is calculated based on the number of unique opens, which differentiates it from click-through rate (CTR), which is calculated on the non-bounce send quantity.   

A higher CTOR is usually better, but since it is a diagnostic, not a business metric, CTOR is rarely, if ever, a key performance indicator (KPI). It’s important to note that the lower your number of unique opens (open rate), the higher your CTOR will appear, even if the number of unique clicks is the same. I discuss this in more detail in “Click, click, click… which click rate is most important for your email campaign?

Tips for Interpreting Click-to-open Rates

CTOR gives you a good, clean read on how effective the body of your email is at driving clicks. It adjusts for any variance in open rate between email messages when you are comparing one to another (or one to many). This can be very useful when you’re doing A/B split testing to boost performance. 

As with CTR, even if a reader clicks on more than one link in an email message, the CTOR will count them only once. This is because CTOR measures the number of unique email addresses (read: people) who clicked on an email, not the total number of clicks on the email. 

See our other articles for examples of other metrics based on clicks like Click-through Rate and Click Reach Rate. 

Related Links

Want to learn more about CTOR and other click-related metrics? “Understanding Marketing Metrics: Email Click Rates” is a good place to begin; you can also check out a piece I wrote for the OI blog called “Click, click, click… which click rate is most important for your email campaign?

How do you identify a successful open rate? “What is a good click-to-open rate?” can help. 

To go deeper on CTOR, you can read “Measuring Email Campaign Effectiveness with Click-to-Open Rate and Other Marketing Metrics,”