CTOR in email marketing: what it is, how it is calculated and how to improve it
The metric that shows whether your content persuades
CTOR (click-to-open rate, or clicks as a percentage of opens) is the percentage of people who click a link in your email after opening it. It measures whether the content of the email persuades the people who have already opened it.
It differs from CTR in what the calculation is based on. CTR divides clicks by all delivered emails. CTOR divides them only by opened emails.
How is CTOR calculated?
The formula is:
CTOR = (unique clicks / unique opens) × 100
For example, you send a newsletter that is delivered to 9,700 people. 2,425 of them open it and 388 click a link:
- CTOR = 388 / 2,425 × 100 = 16%
- CTR = 388 / 9,700 × 100 = 4%
- Open rate = 2,425 / 9,700 × 100 = 25%
Always use unique clicks and opens: if one person opens the email three times and clicks twice, it counts once in each metric.
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CTOR, CTR and open rate: what does each one measure?
| Metric | What it measures | Formula | What it tells you |
|---|---|---|---|
| Open rate | How many people open the email | Unique opens / delivered × 100 | Whether the subject line, the sender and the preheader work |
| CTR | How many people click out of everyone who receives it | Unique clicks / delivered × 100 | The overall result of the campaign |
| CTOR | How many people click out of those who open it | Unique clicks / unique opens × 100 | Whether the content and the call to action persuade |
The three should be read together. For example, a high open rate with a low CTOR means the subject line draws people in, but the content doesn’t deliver on its promise.
What is a good CTOR?
There is no single figure that works for everyone: it depends on your industry, the type of email and the quality of your list. A transactional or welcome email usually gets more clicks than a general newsletter.
The most useful benchmark is your own history. Calculate the average CTOR of your recent campaigns of the same type and compare each new send against that average.
Keep one thing in mind: some opens are registered automatically, for example through Apple Mail’s privacy protection. That inflates opens and makes the CTOR look lower than it really is.
How to improve the CTOR of your emails
- A clear call to action. One goal per email and a visible button, so people don’t have to scroll to see it.
- Deliver on what the subject line promises. If the subject line announces an offer, the offer should be at the top.
- Segment. An email designed for a specific group gets more clicks than a generic one. More in segmentation in email marketing.
- Design for mobile. Large buttons and short text, because most emails are read on a phone.
- Test. Try two versions of the button or the text with an A/B test and keep the one with more clicks.
How Mailrelay helps you
In the statistics of each Mailrelay campaign you can see opens, clicks and unsubscribes. The click map shows which links your subscribers click, so you know which content works best.
Open and click tracking is included in the free account and in the Enterprise plan. With the free account you can send up to 80,000 emails per month and run A/B tests.
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Frequently asked questions
What is CTOR in email marketing?
It is the percentage of people who click a link in an email after opening it. The acronym stands for click-to-open rate.
How is CTOR calculated?
Divide unique clicks by unique opens and multiply by 100. With 388 clicks and 2,425 opens, the CTOR is 16%.
What’s the difference between CTR and CTOR?
CTR calculates clicks over all delivered emails. CTOR calculates them only over opened emails, so it is a better measure of content.
Why is my CTOR low?
It is usually due to content that doesn’t deliver on what the subject line promises, a call to action that is hard to see, or a generic email. Automatic opens also play a part, since they inflate the base of the calculation.
Does CTOR have other meanings?
Yes. In .NET programming, “.ctor” is the internal name of a class constructor. In email marketing, CTOR is always the click-to-open rate.