Free tool · no signup
Click-to-open rate (CTOR) calculator
Work out the share of the people who opened your email who then clicked, with a confidence interval and the click rate it is made of. Then the part every other calculator leaves out, which is that a rising CTOR is usually a falling open rate.
Ungated · no email required · nothing leaves your browser
In short
- Click-to-open rate, or CTOR, is the share of the people who opened an email who then clicked a link in it, calculated as unique clicks divided by unique opens. The free CTOR calculator from SmartReach.io works it out with a 95% confidence interval and shows the click rate and open rate it is composed of beside it.
- Click-through rate is not the same figure. It divides the same clicks by delivered messages rather than by opens, so it measures the campaign rather than the people who opened it.
- The two are linked exactly: click rate equals open rate multiplied by click-to-open rate, because the opens cancel. SmartReach.io splits a change in click rate into the part the open rate caused and the part click-to-open caused, so a click-to-open rate that rose because fewer people opened is not read as a better message.
- It publishes no click-to-open benchmark. Both halves of the fraction are counted by machines and they move it in opposite directions: Apple Mail Privacy Protection has pre-fetched tracking pixels by default since 2021, inflating the opens in the denominator, while security gateways scan and rewrite the links in inbound mail, inflating the clicks in the numerator.
- Neither distortion can be measured from a sender's own report, so SmartReach.io offers no correction for either. It derives the two tells a sender can get from their own figures instead: total clicks divided by unique clicks landing on the number of links in the email, which is the shape a link-scanning gateway leaves, and clicks arriving with no replies behind them.
- More clicks than opens is reported as a fault rather than as a rate above 100%. It is usually total clicks supplied where unique clicks were needed, and it can also be blocked images, where the open never registered while the link still worked.
- The rate is computed on opens rather than on delivered, so its sample is smaller than the campaign size suggests. Below about 200 opens SmartReach.io says so, because the interval is then wider than most differences a sender is trying to detect.
- It also tests whether the difference between two campaigns is statistically significant, with a two-proportion z-test at 95%, reporting an underpowered test separately from one that genuinely found nothing.
- The calculation runs entirely in the browser. There is no endpoint for the figures to be sent to, so campaign numbers are not transmitted, stored or logged, and results are shared through the URL fragment, which no browser sends to a server.
- SmartReach.io is a cold email software with multichannel outreach capabilities via channels like email, LinkedIn, calls and WhatsApp. It reports reply, positive reply and meeting rates per campaign, sequence and mailbox, which are the figures no pre-fetch and no gateway can produce.
These are example figures, so the tool is working when you arrive. Type over them.
Nothing is sent anywhere. The calculation runs in this browser tab.
2304 delivered · 742 opened · 96 clicked
Click-to-open rate
12.9%
95% CI 10.7% to 15.5%
Clicks ÷ opens. Both counted by machines.
Click rate
4.2%
95% CI 3.4% to 5.1%
Clicks ÷ delivered. The one to compare.
How the three fit together
Exact rather than approximate, because the opens cancel. Click-to-open is your click rate with your open rate divided out of it, which is why it climbs when fewer people open.
Open rate
32.2%
95% CI 30.3% to 34.1%
On delivered. Inflated since 2021.
Reply rate
6.0%
95% CI 5.1% to 7.0%
On delivered. No machine writes one.
Clicks per clicker
2.93
Against 3 links in the email
- Read this
Both halves of this fraction are counted by machines, in opposite directions
Apple Mail Privacy Protection has pre-fetched tracking pixels by default since 2021, and Apple describes the feature as preventing senders from seeing whether a message was opened. Those opens are in the denominator here, so they push this figure DOWN, which is the reverse of what they do to your open rate. Meanwhile security gateways follow every link in a message to check it, and a followed link is logged as a click, which pushes the same figure UP. The two are different populations and do not cancel. Neither can be measured from your own report, so nothing here corrects for either.
- Worth knowing
2.93 clicks per clicker, against 3 links in the email
That is the shape a security gateway leaves. Software checking a message follows every link in it, so it registers one clicker and one click per link, and the ratio lands on the number of links. An engaged reader who happens to open most of your links produces the same ratio, so this is a hint rather than a finding, and it cannot be turned into a correction. What it can do is tell you to check whether the clicks arrived within seconds of delivery, which people do not do.
A reply is the click no machine can fake
Pre-fetching manufactures opens and gateways manufacture clicks. Neither writes a reply, which is why SmartReach.io reports reply, positive reply and meeting rates per campaign, sequence and mailbox. The benchmarks for those come from 40M+ emails across 5,000+ campaigns in our State of Cold Email 2026 report.
14-day free trial · no credit card
The definition
What is click-to-open rate?
Click-to-open rate, written CTOR, is the share of the people who opened an email who then clicked a link inside it. SmartReach.io calculates it as unique clicks divided by unique opens, so a campaign with 742 unique opens and 96 unique clicks has a click-to-open rate of 12.9%. It is not the same figure as click-through rate, which divides the same clicks by delivered messages instead and therefore counts everyone the campaign reached rather than only the people who opened it.
Unique clicks over unique opens
Unique on both sides. Total clicks over unique opens counts one person who clicked four links four times above the line and once below it, which is what produces a rate above 100%.
It asks about the people who opened
Everyone counted in it already got past the subject line and the inbox, so what is left is the message, the offer and the link. That is the question click-to-open exists to isolate.
It is a ratio of two rates, not a measurement
Click rate is open rate multiplied by click-to-open rate, so this figure is your click rate with your open rate divided out of it. It moves when either one does, and it cannot tell you which.
The reason this page is longer than a division is that both of those figures are produced by software as well as by people. Pre-fetched opens inflate the denominator and gateway link scans inflate the numerator, in opposite directions, which is covered in what a good click-to-open rate is. The tool above works the rate out with a confidence interval, because its denominator is opens rather than delivered and is smaller than the campaign makes it look.
The question behind the number
Did the message get better, or did fewer people open it?
SmartReach.io splits a change in click rate into the part the open rate caused and the part click-to-open caused, because click rate is open rate multiplied by click-to-open rate, exactly, and the opens cancel. So click-to-open climbs whenever fewer people open and the same people keep clicking. In the campaign below it rises from 12.9% to 16.9%, which reads as a better email, while the click rate falls from 4.17% to 3.67%. The two parts sum to the whole change rather than to something close to it.
The earlier campaign
The later one
Click rate 4.17% then 3.67%−0.50 points
Click-to-open improved and the campaign did not
Where the change came from, in points of click rate
Click-to-open went from 12.9% to 16.9%, which reads as a better email, while the click rate went the other way. Fewer people opened, and the share of those who clicked rose because the denominator shrank. The same readers clicked; there were simply fewer of them to divide by.
The two contributions sum exactly to the change in click rate, with each half valued at the average of the other across both campaigns. A split that moves one factor first instead would hand whichever you chose the overlap between them.
Before you act on it
Is the difference between two campaigns statistically significant?
A click-to-open rate is computed on opens, not on delivered, so its sample is a fraction of the campaign and it moves around more than any other rate in your report. SmartReach.io runs a two-proportion z-test at 95% and answers in words. It reports an underpowered test separately from one that genuinely found nothing, because a small test that found nothing has not shown the two are the same.
Campaign A
Campaign B
12.9% then 17.5%+4.6 points
This difference is unlikely to be chance
At these sample sizes a gap this size would rarely appear if the two were really the same, so it is reasonable to treat the change as real. The difference is somewhere between 0.9 and 8.3 points, which is the range worth planning against rather than the single number above.
Click-to-open is counted by machines on both sides, and they push it in opposite directions, because pre-fetched opens inflate the denominator while gateway link scans inflate the numerator. Two campaigns can differ on it through their recipients rather than their content, so a significant result here is weaker evidence than the same result on reply rate. The denominator is also opens rather than delivered, so the sample is smaller than the campaign size suggests.
Two-proportion z-test at 95%. Not an overlap of the two confidence intervals, which is a much more conservative test and would call real differences noise.
The honest answer
What is a good click-to-open rate?
SmartReach.io does not publish one, and the reason is structural rather than cautious. Click-to-open is the only rate in a campaign report with a machine in both halves of it. Apple Mail Privacy Protection has pre-fetched tracking pixels by default since 2021, and Apple describes the feature as preventing senders from seeing whether a message was opened; those opens sit in the denominator, so they push this figure down while pushing your open rate up. Meanwhile security gateways scan and rewrite the links in inbound mail before it arrives, and a link followed by a scanner is logged by your tracking as a click, which pushes the same figure up. The two are different populations, they do not cancel, and how much of each you have depends on who is on your list.
It will not tell you what a good CTOR is
A benchmark needs the compared numbers to be measured the same way. This one is inflated in the denominator by however much of a list uses Apple Mail, and in the numerator by whichever security gateways protect the recipients. Both vary by list, so two click-to-open rates are not comparable even between your own segments.
It will not strip the machines out of your figures
That would need the share of your recipients with pre-fetching on and the share behind a link-scanning gateway. Neither is in a campaign report and neither is knowable from one. A tool offering a cleaned figure has guessed at both, and the two guesses point in opposite directions.
It will not tell you the clicks were bots
The tells here say what a pattern is consistent with, not what it proves. Clicks per clicker landing on your link count is the shape a gateway leaves, and it is also the shape an engaged reader who opened most of your links leaves. The next step is your click log and its timestamps, not this page.
It will not score your campaign out of ten
A composite hides which input moved, which is the only thing worth knowing on a metric made of two other metrics. Each rate is shown separately, and the change in click rate is split into the two halves that caused it.
Which software clicks the links, and how to spot it
The scanners are not hypothetical and they are not anonymous. Microsoft describes Safe Links, which is on by default for many Microsoft 365 tenants, in its own documentation. “Safe Links provides URL scanning and rewriting of inbound email messages during mail flow, and time-of-click verification of URLs and links in email messages.” Each product rewrites the links it scans to a domain of its own, so a click log is the fastest place to find out how much of a click-to-open rate was people.
| Link scanner | Rewrites links to |
|---|---|
| Microsoft Defender for Office 365, Safe Links | safelinks.protection.outlook.com |
| Proofpoint URL Defense | urldefense.com |
| Mimecast Targeted Threat Protection, URL Protect | protect-<region>.mimecast.com |
| Barracuda Link Protection | linkprotect.cudasvc.com |
Average click-to-open rate, by the sources that publish one
SmartReach.io publishes no click-to-open benchmark of its own. These are the numbers in circulation instead, reported so that the disagreement between them is visible. An average quoted flat at about 11% and an industry table whose top is 38.1% cannot both be the figure to measure yourself against, and none of them was measured on your list, with your share of Apple Mail recipients and your recipients' security gateways.
| Published figure | Published by | What it covers |
|---|---|---|
| about 11% | Smartlead | across all sectors, quoted flat on its own click-to-open calculator |
| 11.1% | Maestra | given as the all-industry average |
| 5.9% to 38.1% | SendGrid, reported by Maestra | by industry, from non-profits at the bottom to computers and electronics at the top |
| 2.66% | Mailchimp, reported by Maestra | the click-through rate average, for the metric CTOR is most often confused with |
The primary sources are better than our summary of them. Apple describes Mail Privacy Protection for iPhone and Mac, Microsoft's documentation for Safe Links, which scans and rewrites URLs in inbound mail during mail flow, and Microsoft's note on blocked picture downloads, which is the case where a click registers and the open that should have preceded it never does. The figure worth benchmarking instead is reply rate, and the open rate calculator does that against 40M+ emails of SmartReach.io first-party data.
The other click rate
CTOR vs CTR: which one should you use?
SmartReach.io calculates both, because they share a numerator and differ in one thing, the denominator, and that one difference decides what each is for. Click-through rate divides unique clicks by delivered messages, so it measures the whole campaign. Click-to-open divides the same clicks by unique opens, so it measures only the people who opened. Use click rate when you are comparing one campaign against another, because delivered is a figure no machine inflates. Use click-to-open when the question is narrower and about the people who did open, knowing that its denominator is one machines are inflating.
| Click-to-open rate (CTOR) | Click-through rate (CTR) | |
|---|---|---|
| What it divides by | Unique opens | Delivered messages |
| What it is trying to measure | The message, judged by the people who saw it | The campaign, judged by everyone it reached |
| How machines distort it | Both halves. Pre-fetched opens push it down, scanned links push it up | The numerator only. Scanned links push it up |
| Sample size it runs on | Your open count, which is a fraction of the campaign | Your delivered count, the whole campaign |
| Safe to compare between campaigns | No, unless the two lists have the same Apple Mail and gateway mix | Better, because delivered is not inflated by anything |
| What a rise can mean | A better message, or simply fewer people opening | More people clicked, from the same denominator as last time |
If the sending is cold outreach rather than a newsletter, a third answer applies. Many first-touch messages carry no link at all, which leaves click-to-open nothing to measure, and both figures are counted by software rather than by people. The State of Cold Email 2026 report, built on 40M+ emails across 5,000+ campaigns, measures to replies, positive replies and meetings booked for that reason.
What to do about it
How to improve your click-to-open rate
SmartReach.io would rather give four things that follow from the numbers on this page than the usual list of personalise, segment and test. Click-to-open is made of two other rates and counted by two different machines, so the first move is always to find out which of those changed before rewriting anything. The four below are in the order they are worth doing.
Check whether the open rate moved first
If the split above attributes the change to the open rate, the message is not what changed and rewriting it will not help. That is a deliverability, subject line or list question, and it is answered by the open rate calculator and the authentication checker rather than by another draft.
Compare a list against itself, never against another list
Two segments carry different shares of Apple Mail recipients and different security gateways, so the same email scores differently on each. A time series for one list is the only comparison where the distortion is roughly constant and a change means something.
Size the difference before you act on it
Click-to-open divides by opens, so a campaign of thousands can be computing it on a few hundred, and a three-point move is routine noise at that size. The significance test on this page answers whether the change you are about to build on is a change at all.
Decide whether the email wants a click or a reply
In cold outreach a link competes with the reply rather than adding to it, and a first touch with no link has no click-to-open rate to improve. Reply rate is the figure neither a pre-fetched pixel nor a link scanner can produce, and it is the one the SmartReach.io State of Cold Email 2026 report measures to.
What is missing from that list is a target to hit, and it is missing on purpose. A number worth chasing would have to be comparable between senders, and the two machines in this fraction are exactly what stops it being comparable. Measure one list against itself over time, and use the open rate calculator to benchmark reply rate, which is the figure on this page that neither machine can touch.
Show the working
How to calculate CTOR, and the rates around it
SmartReach.io publishes every formula this calculator uses, written out. The word doing the work in the first one is unique, on both sides. Total clicks over unique opens is the single most common way a click-to-open rate ends up above 100%, because one person clicking four links counts four times above the line and once below it. Worked through on the campaign this page is seeded with, 96 unique clicks divided by 742 unique opens is 12.9%.
Click-to-open rate (CTOR)
unique clicks ÷ unique opens × 100Unique on both sides. Total clicks over unique opens is the single most common way this number ends up above 100%, because one person clicking four links counts four times in the numerator and once in the denominator.
Click-through rate (CTR)
unique clicks ÷ delivered × 100The same numerator over a different denominator. This is the one to compare between campaigns, because delivered is a number no machine inflates, and it is what most people mean when they say click rate.
The identity between them
click rate = open rate × click-to-open rateExact, not approximate, because the opens cancel. It is the reason a click-to-open rate cannot be read on its own, because it is your click rate with your open rate divided out, so it rises whenever fewer people open and the same people click.
Clicks per clicker
total clicks ÷ unique clicksNot a rate, a shape. A security gateway checking a message follows every link in it, so it contributes one clicker and one click per link. When this ratio lands on the number of links in your email, that is what produced it.
Each rate carries a 95% confidence interval, calculated with the Wilson score method rather than the textbook normal approximation, because the normal one returns impossible bounds at small samples and near 0 or 100%. The threshold that matters here is measured in opens rather than in delivered messages. Below about 200 opens the interval is usually wider than the difference you are trying to detect, and a campaign delivering several thousand messages can still be computing this rate on fewer than that.
Take it with you
Put this CTOR calculator on your own site
SmartReach.io publishes this calculator as an embed, free to use on any site, with no permission needed and nothing to sign. It carries a visible credit back here, which is the whole arrangement. The calculation still runs inside the reader's own browser, so an embedded copy transmits nothing either.
Once you know the number
Where the answer actually is
Click-to-open is a symptom, and its two inputs are counted by software. SmartReach.io publishes a free tool for each of the things underneath it, which are the rates this one is made of, the wording that decides whether a link is ever reached, and the authentication that decides whether the message arrives at all. All of them are on the free tools index, ungated.
The number, and its limits
Open Rate Calculator
Work out open, delivery, reply, click and click-to-open rates from your campaign figures, each with a confidence interval, and see why the open rate is the one you should not benchmark.
What it looks like
300 opens ÷ 900 delivered = 33.3%
What the words cost you
Spam Word Checker
Paste a subject line and body and see the phrases, capitals, punctuation and links that rule-based filters weight against it, and which of them are worth changing.
What it looks like
ACT NOW, 100% guaranteed!!
All three records, one pass
Email Authentication Checker
Check SPF, DKIM and DMARC on any domain at once. See which of the three are missing, which are broken, and which are published but not actually enforcing anything.
What it looks like
SPF pass · DKIM pass · DMARC p=reject
The Apple Mail Privacy Protection behaviour described on this page is documented by Apple for iPhone and Mac. Link scanning in inbound mail is documented by Microsoft for Safe Links, and other mail security gateways behave the same way. The reply and meeting figures referred to here belong to the State of Cold Email 2026 report, SmartReach.io first-party campaign data covering January to June 2026. Last reviewed . The calculation runs in your own browser and nothing you type is transmitted or stored.
FREQUENTLY ASKED QUESTIONS
Click-to-open rate questions, answered
Optimise the number a person had to produce.
A pre-fetch can manufacture an open and a scanner can manufacture a click. Neither writes a reply. SmartReach.io is a cold email software, and its Sales Engagement plans put LinkedIn, calls and WhatsApp in the same sequence as the email, with no per-seat pricing. It reports reply, positive reply and meeting rates per campaign, sequence and mailbox, and authenticates and warms the sending domains those replies depend on.