The Difference Between CTR and CTOR

We’ve all done it. Sent out an email campaign, and then a week later compared the CTOR against the CTR of some ads. Maybe it was in a report we were writing. Maybe it was just in our heads. Maybe that’s just me.

Either way, it’s one of the oldest tricks to fall for in the digital marketing book – thinking that CTOR and CTR are directly comparable.

They are not. CTOR is not the Irish cousin of CTR* (my wife made me promise not to make that joke, but then she doesn’t read this blog so ha!). CTOR is a variation on CTR, but they are pretty different both philosophically and technically.

Let’s take a look at how.


The Difference Between CTR and CTOR


Wait – what are CTR and CTOR?

CTR stands for Click-Through Rate and is used to measure how frequently someone clicks on an ad (or a link). For example, you show an ad 1,000 times on a website, and it gets clicked on 100 times – that means your CTR would be 10%. It’s useful because if you’re advertising in lots of places (or in lots of ways) you need to be able to compare the performance of different things.

CTR levels the playing field so that if you are advertising to 10 people or 10,000 people you can see which set of ads are most effective regardless of the size of the audience you are speaking to.

CTOR stands for Click-To-Open Rate and is used to measure how frequently people click on a link in an email. Just like CTR, CTOR is useful as it means you can compare the success of emails sent to different amounts of people (again, ignoring audience size).



Email Marketing metrics are the best metrics

So CTOR is for click rates in emails, and CTR is for click rates anywhere else. End of story right? Wrong.

The metrics for email marketing are fundamentally different from the metrics for all other digital marketing. This difference begins with the fact that metrics for email marketing ONLY work for email marketing.

While Engagement Rate, reach, and even CTR can be used for basically any type of digital marketing, CTOR cannot. It can only be used for email marketing, as can all of email marketing’s metrics.

[Bounce Rate is kind of an exception to this rule – except it means something very different for email marketing than for websites]

Perhaps it is because email marketing is the oldest form of digital marketing that the metrics it uses are so useful. It’s had time to mature in a way that social media (for example) just hasn’t. Alternatively, perhaps it’s because email marketing has a set of specific stages to get through (which are all controllable by the sender) that these metrics are so useful.

It’s probably both. Let me explain.



Introducing the email marketing metrics suite…

Each and every metric in email marketing is specifically tailored to working out how to get people to the next stage of engagement:

  • Delivery Rate is the percentage of emails that actually made it through to inboxes
  • Open Rate is the percentage of people who received the email and then opened it
  • CTOR is the percentage of people who opened the email and then clicked on anything it
  • Conversion Rate (for emails) is always Click-to-conversion rate – as in the percentage of people who clicked on the email and then converted

There are changes you can make to an email marketing campaign to improve each of these metrics, and each one has a profound effect on how a campaign performs. However, that is not the power of these metrics.

What makes them so powerful is that each ‘rate’ measures a metric as part of the metric above it.


What It Looks Like: Email Marketing MetricsClick to enlarge


Moving people onto the next step

CTOR is the percentage of people who clicked on any link in an email divided by the number of people who opened the email. Only people who opened the email are actually physically capable of clicking on anything within it. So by using this measure (as opposed to a percentage of people who received the email), you are narrowing the focus to only on what is directly possible. You are focussing entirely on how much people are engaging with the content of the email, not on the overall performance of the email.

If you measured the people who clicked as a percentage of people who received the email (CTDR if you will) instead of CTOR then you would be focussing more on the clicks you received. “I sent X emails – what percentage of emails resulted in a click”. It becomes more of an ROI sort of measure than an engagement measure.

This sort of thinking is what drives the rest of digital marketing – and it makes a certain amount of sense in most contexts. If you want to compare different forms of digital marketing, a CTR-type measure like this can help you contrast audiences across channels.



A stable audience

However, for email marketing, there is a crucial difference – you don’t have to pay for a larger audience. If you want a display ad or a social media ad to be seen by more people then you generally need to pay more. With email marketing, the size of your audience is already set.

Sure you can run lead gen campaigns to increase the size of your email marketing list. However, audiences for emails are limited by list size, whereas for ads (of all stripes) the total audience is essentially unlimited. This makes the fundamental nature of email marketing significantly different. Instead of working towards finding an engaged audience, it is working towards further engaging your current audience.

So instead of a brute force calculation like CTR, you get the finesse of CTOR. Instead of saying “I spent X dollars, how many clicks did that get me”, email marketers say “I wrote X message, how many people did that resonate with”.


CTOR Formula or Click-To-Open Rate EquationClick to enlarge

CTOR = (Clicked x 100) ÷ Opens


Clicks out of what?

Now that we’ve covered why CTOR is functionally different to CTR, let’s take a look at how it is technically different.

CTR is the number of clicks as a percentage of the number of times an ad or link was loaded. This is very different to CTOR, which is the percentage of people who clicked out of the number of times an email was opened.

This is important because, firstly, CTR isn’t measuring people like CTOR is – it’s measuring actions. CTR directly measures clicks themselves. This has the disadvantage of potentially capturing the same people multiple times.

Secondly, by comparing clicks against impressions – CTR is casting its net too wide. Most ad impressions aren’t actually seen by anyone so this is a bad set of people to be comparing against. With CTOR, the minimum thing you know is that the people who could potentially click did definitely open the email. This makes CTOR a much more useful metric immediately.

No guarantees that they care

Thirdly, an impression in no way implies that the user is interested in the ad. An impression for an ad should, in theory, appear on a webpage where someone is likely to click. Either by human planning or algorithmic magic, every ad shown online should be seen by someone who is interested. However, as anyone who has ever used the internet can tell you – this is definitely not the case.

Just because a person sees an ad, doesn’t mean they are interested in it. With CTOR, the exact opposite is true. A person has received an email, decided that they are interested enough to open it, and then specifically looked in that email to see if they are interested enough to do anything about it. This creates an engaged audience, who are much more likely to click than on a random ad on the internet.


Calculator IconWork out the CTOR of your emails with our Click-To-Open Rate Calculator >


Clicked, not clicks

Impressions and Opens are what is known as the denominator of CTR and CTOR. They are the bottom part of the equation – the audience that is being measured if you will. It’s important to take note of the top of the equation too. The numerator (as it is known) shows what is being measured.

While the denominator clash (Opens vs Impressions) naturally push CTORs to be higher than CTR, the same can’t instinctively be said about Clicked vs Clicks. For CTR, clicks might record the same person multiple times. For CTOR, the number of users who clicked on any content feels like it will naturally be a lower number.

One person could click on five links in an email and still only count once towards the CTOR after all!

Therein lies the rub. An email has multiple things to click on. An ad will only have one click-through (in almost all cases). This means that the (pre-engaged) audience of people who opened an email have a veritable smorgasbord of options to click on. All they have to do is like one single link and bam! they are included in CTOR.

With an ad on the other hand, it’s all or nothing – click this or ignore it. This essentially makes CTOR function like it is multiple CTRs combined. This, in turn, drives CTORs to be naturally higher than CTRs.


CTR BenchmarksClick to enlarge


On the other hand… they both measure engagement

Having said all this about how different CTR and CTOR are, it should be noted that actually CTR and CTOR are essentially useful for the same thing. While you should always use conversions as the ultimate measure of your success, CTR and CTOR are both reasonable backup metrics.

Both CTR and CTOR are useful to see roughly how interesting your message is, whether in an ad or in an email. They are both forms of engagement rate in their own way (even if CTR is more similar to ROI).

In fact, CTR for an ad with a single click-through is identical to the engagement rate for that same ad. Similarly, CTOR can be said to be email marketing’s version of engagement rate in everything but name (well the Facebook version of Engagement Rate anyway).

The final difference is where this engagement lies. CTR is a top of funnel metric, while CTOR is from the middle of the funnel. CTR faces an uphill battle as it is a measure of whether an ad (or whatever) is cutting through the noise of the internet at large. CTOR, on the other hand, is for looking at an engaged audience and seeing if the message in a specific email is taking them to the next level of engagement.


To Summarise

  • CTOR measures people. CTR measures actions.
  • CTR measures against impressions (which haven’t even necessarily been seen by anyone).
  • CTOR measures against opens which means the audience has already expressed interest in the message
  • CTOR measures people who have clicked on any one of multiple links, while CTR is for only a single link. This makes CTOR function like a set of CTRs combined.
  • CTR is ToFu while CTOR is MoFu.
  • They are both essentially versions of engagement rate.


The difference between CTR and CTORClick to enlarge


*You know… because Irish names often have an O’ in the middle of them? Like O’Driskill? So what I was implying was that some people might think CTOR stands for Click-Through O’Rate. Get it? Ok it is a terrible joke. I am very sorry. Especially to Irish people, or anyone who read this blog post. Also to my wife, who I force to read it, and will know of my disrespect. I am sorry. Sheesh.