In short, it’s a sometimes used email reporting metric. Other metrics like open rate and click-through rate (CTR) are more common…but perhaps not as valuable.
Although email marketers are used to seeing it mentioned, maybe even in their own email reporting, that doesn’t necessarily mean everyone knows what it is or why it matters. And we should, because this one piece of information can be quite insightful.
That’s because your CTO indicates your engagement. Click to open means how many click throughs did you get in relation to how many opens. It combines your open rate and CTR.
That makes it a way of measuring the effectiveness of your content. You can have a great open rate and a poor CTR. You can have a poor open rate and a great CTR. But really your goal is a great CTO because that means you’ve engaged:
Great open rate + Great CTR = Engagement
And that’s what the CTO measures.
The reasoning behind the CTO metric
A nice CTO means that you lived up to the promise of your email. If you had a high open rate but a poor CTR, that would indicate you made a promise (i.e. your subject line) but didn’t deliver. If, on the other hand, you had a poor open rate but a high CTR, that indicates your email had compelling content that people liked and wanted to react to.
Your job is to achieve both, to get the opens and to get those people who opened your email to click through.
Using the CTO as a critical email reporting metric can help you achieve that goal.