Click-to-Open Rate (CTOR)
Click-to-open rate (CTOR) is the percentage of recipients who opened an email and then clicked at least one link in it. It is calculated by dividing unique clicks by unique opens. CTOR isolates how well the email’s content and calls to action performed, separate from how well the subject line earned the open.
Click-to-Open Rate Formula
Divide unique clicks by unique opens, then multiply by 100:
CTOR = (Unique Clicks / Unique Opens) × 100
A campaign with 2,000 unique opens and 240 unique clicks has a CTOR of 12%. Campaign Monitor defines the metric the same way: unique clicks divided by unique opens.
Use unique counts on both sides of the fraction. If you divide total clicks by unique opens, one recipient clicking five links counts five times. The result overstates engagement and can even exceed 100% on short lists.
Most email service providers (Mailchimp, Klaviyo, HubSpot) report CTOR directly or show both inputs on the campaign report. Delivered and sent counts do not appear in the formula at all. That is the main thing that separates CTOR from click rate.
CTOR vs CTR in Email
CTR and CTOR share a numerator but use different denominators:
- Email CTR (also called email click rate) = unique clicks ÷ delivered emails. It measures the whole campaign, from subject line to button.
- CTOR = unique clicks ÷ unique opens. It measures only the email body, among people who opened.
With 10,000 delivered, 2,000 opens, and 240 clicks, CTR is 2.4% and CTOR is 12%. Same clicks, different question. The general click-through rate used for ads and search follows the CTR logic, not the CTOR logic.
Reading the two together with email open rate tells you where a campaign broke:
| Open rate | CTOR | What it usually means |
|---|---|---|
| High | High | Subject line and content both worked |
| High | Low | Subject line oversold, or the CTA was weak |
| Low | High | Content worked, but few people saw it |
| Low | Low | Wrong audience, poor timing, or deliverability problems |
What Is a Good CTOR?
A good CTOR falls between 6% and 17%, depending on industry, according to Campaign Monitor. Its benchmark data put the all-industry average at 10.5% in 2021, down 3.6 points from 2020.
Industry spread in the same Campaign Monitor data:
- Real estate, design, and construction: 17.2%
- Education: 15.7%
- Government and politics: 14.3%
- Travel, hospitality, and leisure: 8.7%
- Wellness and fitness: 6.0%
- Retail: 5.8%
GetResponse’s 2024 benchmark report, based on 4.4 billion emails sent in 2023, puts the average CTOR at 8.62%. The same report shows a 39.64% open rate and a 3.25% click-through rate.
Treat any published benchmark as a rough band, not a target. Your own trailing average across the last 10 to 20 sends is the better comparison.
How Apple Mail Privacy Protection Lowers CTOR
Apple Mail Privacy Protection (MPP), launched with iOS 15 in September 2021, pushes CTOR down artificially. MPP pre-loads email images on Apple’s servers, which registers an open whether or not the person read the message. Opens inflate, clicks do not, so the denominator grows while the numerator stays the same.
Example: 2,000 real opens and 240 clicks give a 12% CTOR. Add 2,000 machine opens from Apple Mail users and CTOR drops to 6%, with no change in reader behavior. Campaign Monitor attributed the 2021 drop in average CTOR to this shift.
Two fixes keep CTOR usable:
- Exclude machine opens. Klaviyo tags these as Apple Privacy Opens, so you can filter them out of the open count before calculating CTOR.
- Watch the numerator too. Corporate security scanners (Microsoft Defender Safe Links, Mimecast, Barracuda) can request every link in an email before delivery. That inflates clicks and CTOR. The click analytics breakdown of bot and scanner clicks covers how to spot them.
How to Improve Click-to-Open Rate
CTOR responds to what happens after the open, so work on the email body:
- Lead with one primary CTA. Put it above the fold and repeat it once near the end.
- Use buttons, not buried text links. Buttons are easier to tap on mobile.
- Match the body to the subject line. A subject line that promises something the email does not deliver raises opens and lowers CTOR.
- Segment the list. A narrower, relevant send beats one generic newsletter.
- Track clicks through to the site. CTOR stops at the click. Tag every link with linkutm’s email UTM builder so GA4 shows which clicks turned into sessions and conversions.
Frequently Asked Questions
What is CTOR in email marketing?
CTOR stands for click-to-open rate. It is the percentage of recipients who clicked a link after opening an email. Marketers use it to judge the email’s content and CTA, separately from the subject line, which drives the open.
How do you calculate click to open rate?
Divide unique clicks by unique opens and multiply by 100. An email with 240 unique clicks and 2,000 unique opens has a 12% CTOR. Use unique counts for both numbers so repeat clicks from the same person do not inflate the result.
What is a good CTOR benchmark?
A good CTOR is roughly 6% to 17%, according to Campaign Monitor. Its all-industry average was 10.5% in 2021. GetResponse reported 8.62% for emails sent in 2023. Industries such as real estate and education sit at the top of the range. Retail and fitness sit near the bottom.
Is CTOR or CTR better for email?
Neither replaces the other. CTR shows how the full campaign performed against everyone who received it. CTOR shows how the content performed among people who opened it. Because Apple Mail Privacy Protection inflates opens, CTR is the more reliable headline metric. CTOR is most useful when machine opens are excluded.
Can click-to-open rate be over 100%?
Not when it is calculated correctly with unique clicks and unique opens. A CTOR above 100% means total clicks were divided by unique opens, or clicks were recorded from people whose opens were never tracked (for example, images blocked). Switch both inputs to unique counts.
To see which email clicks turn into site visits, tag your newsletter links with the free email UTM builder at linkutm.