CTOR vs. CTR: Which Is More Important in Email Marketing?

Emails consist of multiple parts—subject lines, preview text, content blocks, images, calls to action. On top of that, there’s sending time, frequency, audience behavior, and dozens of other little details that all play a role in how well your message performs.

Can you immediately say which of these aspects is the most important? Probably not. Your subject line might be intriguing, but your content is dull. Or you could write a super engaging newsletter and ruin its impact by sending it too often, too rarely, or simply at the wrong time of day.

To really understand how all these elements work together—and where they might be failing to perform—you need to measure them. Some of the metrics that can help here are CTOR (click-to-open rate) and CTR (click-through rate). 

CTR provides the overall picture of how an email is performing. When you need to analyze your emails from the inside out—that’s where CTOR becomes essential.

So, while the name of this article is CTOR vs. CTR, these two metrics aren’t competing—they’re collaborating. In this article, we’ll break down the differences between click-through rate and click-to-open rate, answer the “What is click-to-open rate?” question, and understand exactly what each metric is responsible for—and how to use both to your advantage.

What Is CTOR?

Click-to-open rate shows how well your email performs after it’s been opened. It tells you how many people clicked a link in your email out of those who actually opened it. In other words, it isolates the performance of the content itself—the design, the copy, the offer, and the CTA. If your goal is to figure out whether your email was worth reading once someone clicked into it, CTOR is the metric you need to analyze. 

The CTOR formula looks like this:

CTOR = (Unique Clicks ÷ Unique Opens) × 100

Let’s say 1,000 people received your email. Out of those, 200 opened it. And 40 people clicked on a link inside. Your CTOR would be: (40 ÷ 200) × 100 = 20%. That means one in five people who opened the email found something interesting enough that was worth clicking.

This makes CTOR a very content-sensitive metric. It doesn’t care about deliverability or subject lines—only what happens after the email is opened. So, if your open rate is high but your CTOR is low, the problem likely isn’t the timing or the targeting—it’s the content of the email itself. 

CTOR is a valuable metric for when you are testing different email formats, calls to action, or interactive elements. 

What Is CTR?

Click-through rate is one of the most important email marketing metrics—and for good reason. It provides you with a quick understanding of how your campaign performed as a whole. CTR shows you how many people clicked on a link in your email out of all the people who received the email, regardless of whether they opened it or not.

The CTR formula looks like this:

CTR = (Unique Clicks ÷ Total Delivered Emails) × 100

So, if you sent an email to 1,000 people, and 20 of them clicked a link, your CTR is 2%. This number combines all parts of your email, such as subject line, preview text, CTA, content, and even time sent, into one result. If CTR is low, it could mean the email didn’t get opened or that even the people who opened it didn’t engage with it. It doesn’t tell you why, but it gives you a reliable performance indicator.

If we talk about click-through rate vs. click-to-open rate, CTR is the broader metric. 

While CTR is best when you compare one campaign to another or analyze overall campaign’s responsiveness, it is not a great tool for understanding how good your actual content is. That’s CTOR’s job. 

When to Prioritize One Metric over the Other

Now that we’ve figured out which metric measures which part of your campaign, it becomes easier to understand their use cases. But in most cases, the real question isn’t when to prioritize one over the other but rather how to combine both for the best possible outcome.

The answer depends on what you are trying to measure.

If your goal is to understand how well your campaign is performing overall—from the moment it arrives in a user’s inbox—then CTR is your choice. It gives you a big picture and answers questions like Was my subject line strong enough? Was my personalization effective? Is my list still engaging at all? It reflects everything, and, as we’ve already mentioned, it can act as an early warning sign that something is off in your broader strategy.

At the same time, CTOR is your next-level indicator. Once you know your campaign is performing reasonably well on a macro level, CTOR helps you understand the details. CTOR measures the quality of your content—the inside of your email.

So, for example, if your open rates are strong but CTOR is low, it tells you that people were curious enough to open but not convinced enough to click. That’s a clear sign that your content needs improvement, while your list or your subject line is probably fine.

In the end, both metrics matter. They serve different purposes and probably belong to different stages of campaign evaluation. But, used together and sequentially, they provide you with a clear picture of both the inside and outside of your campaign.

What CTOR and CTR Can’t Tell You

As useful as CTR and CTOR are, they’re still just part of the story. These two metrics show you what happened—but not always why it happened. And sometimes, focusing too much on the numbers alone can be misleading.

A high CTR might look great in your report, but it doesn’t tell you what happened after the click. Did the person stay on the landing page? Did they bounce after two seconds? Did they buy something, or just window-shop? CTR tells you that a link was clicked—not whether the outcome was meaningful.

CTOR has its own blind spots: it can’t tell you whether a recipient opened the email out of habit or just to clean their inbox. Nor can it tell you how they felt about what they saw. Someone might click a link simply to figure out what it is—and not because the message was captivating.

And neither CTR nor CTOR can tell you if your email converted. In the end, these metrics measure interaction, not intent. They don’t capture if a lead became a customer or if someone forwarded your email to a colleague who later converted. They can’t read tone, sentiment, or emotion either. 

That’s why it’s important not to treat these metrics as the ultimate goal but to use them as indicators that can help you identify trends. At the same time, keep on exploring an overall context: track post-click behavior, watch conversions, and read the replies. 

How to Improve Both CTR and CTOR

Imagine that you received your performance report, and you are not quite happy—neither with your CTR nor your CTOR, or maybe both. Here comes the logical question: how can you improve these metrics?

While these metrics measure different stages of the reader’s journey, the ways to improve them differ too. But the good news here is that you don’t need two separate strategies to do so. With the right adjustments, you can optimize both metrics of your campaign and make your user experience overall better.

To improve your CTR, you need to focus on what happens before someone opens your email—things like subject line, preview text, sender name, and even the time you send the email. All the factors that impact a recipient’s willingness to click in. Here, segmentation might be your best friend. It will help you send more targeted messages, experiment with timing, and make sure that a subject line fits the recipient best.

So, when you want to improve your CTR, you should keep in mind that here you need to focus on grabbing the recipient’s attention before they even click on your email. That should be love at first sight—without looking deeper.

The second stage is your CTOR. Here, you need to focus on your content. You need to align the promise of your subject line with the content of your email. Evaluate whether your copy was engaging and if your CTA was obvious enough. To improve your CTOR, it is important that you keep your email structured, clear, visually appealing, and emotionally engaging. Here, you can also A/B test your layouts, CTA placements, and tone of voice. Sometimes even slight changes can impact CTOR.

And please don’t forget that these two metrics are connected. A clear subject line will not only improve your CTR but will also prepare the reader for better interaction with your content. The reverse is true as well—if your CTR and copy are aligned, people are more likely to remember your emails in the future.

To Sum Up: Don’t Choose—Align Your Metric to Your Goal

In this article, we talked about CTOR and CTR metrics—and if you’re still approaching them as CTOR vs. CTR, the answer is simple: it’s not about picking sides. Both metrics provide valuable insights. What matters is knowing when to use them—at which stage of your campaign and for which aspect of performance. 

They also only make sense when aligned with other important indicators. So, everything really comes down to knowing what you’re measuring and why. Instead of comparing click-through rate versus click-to-open rate, shift your mindset. You’re not choosing between them—you’re looking at two different types of engagement, each meaningful in the right context.