KPIMarketing

Email Click-to-Open Rate (CTOR)

Percentage of email openers who also click a link, measuring content relevance

What is Email Click-to-Open Rate (CTOR)?

Click-to-open rate is the percentage of people who opened an email and then clicked a link in it. It measures how compelling the content of the email was once someone was already reading it.

Because it only counts people who opened, it separates the quality of the content from the effect of the subject line. That makes it more useful than click rate for judging the email body and its calls to action.

How this KPI is measured

Function: Marketing
Sub-function: Email Marketing
Industry: All Industries
Type: Lagging
Impact: Efficiency
Unit: %
Measurement frequency: Weekly / Monthly
Formula: (Unique clicks / Unique opens) × 100

How to calculate it

Divide the number of unique clicks by the number of unique opens, and multiply by 100.

For example, if an email was opened by 4,000 people and 600 of them clicked a link, the click-to-open rate is (600 / 4,000) x 100 = 15%.

Be aware that open tracking has become less reliable because some mail programs pre-load images, which can overstate opens. Treat it as a directional measure and compare emails sent to the same audience.

Where it is used

Testing email content
Compare layouts, copy and calls to action to see which prompts more action from readers.
Separating subject-line effects
Use it alongside open rate to tell whether a problem is getting opened or getting clicked.
Assessing segments
See which audience groups find the content most relevant.

How to improve it

Focus each email on one main actionA single clear call to action usually beats several competing ones.
Make the link prominentUse a clear button or link near the top, described in specific words.
Match content to the audienceSegment the list so the message is relevant to the people receiving it.
Test copy and layoutChange one element at a time and keep the version that earns more clicks.
Design for mobileCheck that links are easy to read and tap on a small screen.

Tips and common mistakes

Do not rely on opens alone. Privacy features make them less accurate than they used to be.
Compare rates only between similar emails to similar audiences.
A high rate on a small number of opens can be misleading. Look at the absolute numbers too.

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