Click to Open

Click-to-open (CTO) is one of many metrics used to measure the effectiveness of email campaigns. It represents the ratio of unique clicks to unique opens, indicating how many recipients who opened the email also clicked on a link within it.

CTO Formula:

CTO=(Unique Clicks÷Unique Opens)​×100

Steps to Calculate CTO:

  1. Identify Unique Opens: Count the number of unique recipients who opened your email. Each recipient is only counted once, even if they open the email multiple times.
  2. Identify Unique Clicks: Count the number of unique recipients who clicked on any link within the email. Again, each recipient is counted once, regardless of how many links they clicked.
  3. Apply the Formula: Divide the number of unique clicks by the number of unique opens and multiply the result by 100 to get the percentage.

Example Calculation:

  • Unique Opens: 1416
  • Unique Clicks: 72


In this example, the CTO is 5.08%, meaning that 5.08% of the recipients who opened the email clicked on a link within it.

Importance of CTO:

  • Engagement Insight: The CTO provides insights into how engaging your email content is for the recipients who open it.
  • Content Effectiveness: It helps measure the effectiveness of your email's content, layout, and call-to-action (CTA).
  • Improvement Areas: A low CTO indicates that, while people are opening your emails, they are not finding the content compelling enough to click through, suggesting a need for content or design improvement.

A good CTO  is considered to be 6-17% according to Campaign Monitor. Check out this to discover Click to Open benchmarks by industry.

By regularly monitoring CTO, you can better understand recipient behavior and optimize your email campaigns for higher engagement and conversions.