Click-to-Open Rate

Back when email performance was read as a single number, open rate held that spot. It measures how many recipients opened the message, and it's where the subject line either works or doesn't.

The trouble is that it says nothing about what happened after the open. When Pagedeck sent a feature announcement to 50,000 addresses, the number Ravi brought to the review was a 42 percent open rate. Twice the industry average, and everyone in the room heard it as a success. Then Grace asked how many people had actually landed on the page, and there was no answer. The real figure was 380 clicks. Twenty thousand people opened the email and 98 percent of them closed it without touching anything.

Dividing those clicks by the 50,000 sent gives 0.76 percent, which creates a different problem. That number mixes together people who never opened because the subject line was weak and people who opened and found nothing worth clicking. A low result tells you something is wrong without telling you whether to rewrite the subject or the body.

Click-to-open rate (CTOR) separates the two by changing the denominator from messages sent to people who opened. The subject line's performance is already accounted for by open rate, so what's left in this number is only what happened after the open — whether the body and the offer were worth walking into.

Divide the number of people who clicked a link by the number of people who opened the message. Send 50,000 emails, have 19,000 open and 1,140 of those click, and 1,140 ÷ 19,000 gives 6 percent.

Two things get in the way of counting it cleanly.

1. Count people, not clicks. Someone who clicks the same link three times counts as one. Summing raw clicks lets a handful of enthusiastic readers carry the whole figure, which makes an email that a hundred people clicked once look identical to one that ten people clicked ten times.
2. The open count itself is unreliable. Most tools embed a tiny image in the body and record an open when that image gets fetched. A reader with images blocked therefore registers as never having opened, and a mail app that pre-fetches inbox messages registers opens for people who never read anything.

Because the denominator wobbles for that second reason, the number is worth more as a trend under stable conditions than as an absolute level. Moving from 6 percent last month to 9 percent this month means the changes made to the body landed.

Two more numbers belong on the same line. Deliverability, the share of sent mail that reached the inbox rather than the spam folder, sits in front of everything, and unsubscribe rate, the share of recipients who ended their subscription afterward, sits at the end. The four numbers line up in the order a message passes through them.

A recurring newsletter usually lands somewhere between 5 and 15 percent, while a trigger message — one that fires off the moment a specific action happens — runs far higher. A notice sent the instant a payment fails can clear 30 percent, because it reaches only people dealing with that exact problem right now.

That makes comparisons inside your own list more useful than comparisons against anyone's average. Three ways to slice it.

1. Read it paired with open rate. A 40 percent open rate with a 2 percent CTOR says fix the body, not the subject. A 5 percent open rate with a 20 percent CTOR says the people who came in were satisfied, so work on the subject line and the send time.
2. Split the audience. An overall 6 percent can hide 14 percent among accounts younger than a month and 2 percent among accounts past six months. What needs fixing there is the recipient list, not the email.
3. Watch unsubscribe rate alongside it. If CTOR went up and unsubscribes went up with it, the email didn't persuade people, it baited them.

There are easy ways to move the number. Drop in ten links or sharpen the button copy and it rises immediately. So the thing worth targeting isn't the rate but the number of people who did the intended thing after arriving. An email with a 3 percent CTOR that got 200 people to turn on a feature beats one with a 9 percent CTOR that got 40.

"Open rate is fine but click-to-open is 2 percent. The subject works — let's rewrite the body."

Getting people to open already succeeded, so the fix belongs inside the message.

"This is a trigger email, so it should hit 20 percent. Don't judge it against newsletter numbers."

Different kinds of email carry different expectations and shouldn't share a benchmark.

"Click-to-open went up but the number of people turning the feature on didn't move."

The email got clicked and something blocked people on the page they landed on.

At Pagedeck, Ravi tunes the weekly product update with this number. Last quarter it was stuck at 3 percent, and breaking it apart showed the cause was the list rather than the writing. Twelve thousand addresses that had never once opened were still on it, contributing almost nothing to the denominator while quietly dragging deliverability down.

Ravi sent that group one final notice and removed them. The send volume dropped from 50,000 to 36,000 and the rate went to 7 percent. What Grace checked in that review was not the rate but how many teams upgraded to a paid plan after the email.

The most common mistake is reading a high number as a good email. A rising percentage simply sounds like good news. But this number stops counting at the click. Load the message with links and lines like "check it out now" and the rate climbs reliably, while the people who arrive and find it wasn't what they wanted stop opening the next one. Six months later the rate has doubled and both open rate and list size have fallen.

Comparing directly against other companies or industry averages is the other one. Open tracking works differently from tool to tool, and the share of recipients using pre-fetching mail apps differs from list to list. Your 6 percent and someone else's 12 percent were measured with different rulers. The number to compare against is your own from last month.