To calculate click-through rate (CTR), divide clicks by impressions and multiply by 100:
CTR (%) = (clicks ÷ impressions) × 100
In a hypothetical campaign, 250 clicks ÷ 20,000 impressions × 100 = 1.25% CTR. That means the report recorded 1.25 clicks for every 100 impressions. Google Ads uses this clicks-to-impressions definition.
The math is quick. Deciding what the result means takes a little more care: you need the right counts, a fair comparison, and a check on what happened after the click. Every numerical example below is hypothetical, not a reported campaign result.
Key Takeaways
Divide clicks by impressions, then express the result as a percentage.
Combine campaigns by adding their clicks and impressions, not by averaging their CTRs.
Compare matching groups and check conversions and cost before judging performance.
Select the campaign, ad, or other group you want to measure. Use the same date range, time zone, and filters for both clicks and impressions. Record the click column's exact name. A report may offer all clicks, link clicks, or another measure; changing that choice changes the question you are answering.
Impressions count appearances under the platform's reporting rules, not unique people. One person may account for several impressions. A 1.25% CTR therefore does not mean 1.25% of the people who saw an ad clicked it.
2. Divide clicks by impressions
For the hypothetical campaign above:
text
250 ÷ 20,000 = 0.0125
Use the unrounded counts from the same report where possible. Don't divide this week's clicks by last month's impressions or combine paid clicks with organic impressions.
3. Convert the result to a percentage
text
0.0125 × 100 = 1.25%
Keep the counts alongside the result: 250 clicks / 20,000 impressions, CTR 1.25%. Someone reviewing the report can then check both the calculation and the amount of data behind it.
Check what your channel counts
Reports can use the label “CTR” for different counts. Check what goes above and below the dividing line before you compare channels.
Channel or report
What the rate measures
What to watch
Google Ads
Clicks divided by impressions
Network, ad scope, and click definition
Google Search Console
Search-result clicks divided by impressions
Search type, query, page, country, and device
Mailchimp email click rate
Delivered-email recipients who clicked divided by successfully delivered emails
Unique recipients, not total clicks or ad impressions
YouTube impressions CTR
How often registered thumbnail impressions led to views
Registered impressions, not all traffic or all video views
On YouTube, total views divided by thumbnail impressions will not give the platform's CTR. Some views come from sources outside its registered-impression count. Use the reported impressions CTR.
Calculate CTR in Excel or Google Sheets
Put clicks in cell B2 and impressions in C2. When both cells contain valid numeric counts, enter:
excel
=IF(C2=0,"N/A",B2/C2)
Format the result cell as Percentage, with two decimal places. With B2 set to 250 and C2 set to 20000, it displays 1.25%.
Percentage formatting already turns 0.0125 into a displayed 1.25%. If you also multiply the formula by 100, the percentage-formatted cell will incorrectly show 125%.
Handle these cases before filling the formula down a sheet:
Zero clicks, positive impressions: CTR is 0%. For example, 0 / 500 = 0%.
Zero impressions: CTR is undefined. Show “N/A,” not 0%.
Missing or unavailable counts: Keep them marked as unavailable until you have valid data. A blank cell must not silently become a measured zero.
Positive clicks, zero impressions: Check scope and reporting definitions before calculating. The two columns may not describe matching events.
Combine CTR using total clicks and total impressions
For an overall CTR, add matching clicks and impressions first, then divide. Larger campaigns must carry more weight because they contributed more impressions.
Suppose two hypothetical campaigns use the same click definition and reporting period:
Campaign
Clicks
Impressions
CTR
A
50
1,000
5.00%
B
100
10,000
1.00%
Combined
150
11,000
1.36%
The calculation is 150 ÷ 11,000 × 100 = 1.36%, rounded to two decimals. Averaging 5% and 1% gives 3%, which treats both campaigns as equally large. They are not.
For rows 2 through 10, use =IF(SUM(C2:C10)=0,"N/A",SUM(B2:B10)/SUM(C2:C10)) and format the result as a percentage. Include only matching, complete rows. Leaving out a row's clicks while keeping its impressions in the total also gives the wrong answer.
Interpret CTR against a fair comparison
There is no single good CTR for every campaign. Google says a good CTR depends on what you advertise and the network. Start with a matching group in your own reports.
Compare the same platform or network, audience type, format, device, and time window. For search, separate brand queries from nonbrand queries. A person searching for your business by name is doing something different from a person exploring a broad category.
Check whether the impression mix changed
An overall CTR can fall even when every group's CTR stays the same.
Consider two hypothetical periods. Brand search keeps a 10% CTR and nonbrand search keeps a 1% CTR. In the first period, each gets 1,000 impressions: 110 clicks from 2,000 impressions gives a combined 5.5% CTR.
In the second period, brand still gets 1,000 impressions, but nonbrand gets 9,000. The total is now 190 clicks from 10,000 impressions, or 1.9% CTR. Neither group's CTR declined. The lower-CTR group simply accounts for more of the impressions, while total clicks increased.
Before rewriting ads because the total dropped, check whether delivery moved toward a different audience, device, placement, or query group.
Show small counts beside the percentage
Both 1 click from 20 impressions and 500 clicks from 10,000 impressions produce 5% CTR. The first result moves to 10% with just one more click at the same impression count. Treat it as an early observation, not a firm performance ranking.
There is no single impression count that makes every comparison sound. For a planned test, choose a sample target based on the baseline rate and the change you need to detect. Avoid declaring a winner just because an early percentage looks large.
Separate percentage points from percent change
A hypothetical rise from 2% CTR to 3% CTR is:
1 percentage point higher: 3% minus 2%.
A 50% relative increase: (3% minus 2%) divided by 2%.
Name which one you mean. “CTR increased by 1%” leaves readers guessing. If the starting CTR is zero, a relative percentage increase is undefined; report the counts and percentage-point change instead.
Check conversions and cost after the click
CTR tells you how often counted impressions produced counted clicks. It does not tell you whether those clicks became qualified leads, sales, or profit.
A hypothetical ad can earn more clicks while bringing fewer qualified leads. Another can have a lower CTR but a lower cost per sale. Review the conversion count, conversion definition, and cost per desired outcome before calling either ad better.
Use the same report settings for conversions. Allow the same time for leads or sales to appear. A newer campaign may still be waiting for leads or sales that an older one has already recorded.
Also distinguish ad clicks from analytics sessions. Google Ads can count a click even when the website does not load. Sessions are a separate measure, so hypothetical totals of 250 clicks and 210 sessions do not by themselves prove that 40 people were lost or that the page had a 16% drop-off rate.
First check date ranges and traffic filters. Check what each event counts and where tracking works. Then investigate page-load problems or redirects if the evidence points there. A gap between counts can show you what to check next. It does not prove the cause.
Turn your CTR report into one concrete test
Fill out a short diagnosis before changing anything. This worked worksheet uses a hypothetical nonbrand search campaign; its figures and thresholds illustrate a decision, not a benchmark.
Worksheet field
Filled example
Scope
US nonbrand search, mobile, August 1–14; one account time zone
Counts and definition
250 Google Ads clicks / 20,000 impressions
CTR
1.25%
Matched comparison
Same scope, July 18–31: 300 clicks / 20,000 impressions, or 1.50%
Conversion and cost check
Current: 10 qualified leads and $500 spend, or $50 per lead. Prior: 12 leads and $600 spend, also $50 per lead. Same reporting settings and conversion window.
Observation
CTR fell 0.25 percentage points; cost per qualified lead stayed the same.
Hypothesis to investigate
The headline may be less useful for the queries now receiving impressions. Query mix could also explain the change.
Next check
Compare query groups and their impression shares before changing the headline.
Proposed test
If comparable query groups also declined, test one headline that states the offer more clearly. Keep the offer, landing page, and targeting unchanged.
Success and guardrail
Seek a credible CTR improvement while keeping cost per qualified lead at or below the business's hypothetical $50 ceiling and lead qualification rules unchanged.
Review plan
Set a sample target before launch, cover a full weekly cycle, and allow the same conversion delay. Call insufficient evidence inconclusive.
Use a platform experiment or randomized split where available. Changing a headline and comparing next week with last week can suggest a direction, but it cannot isolate the headline's effect from other changes.
Start with one matching report, calculate the rate, and inspect the groups behind it. Then use conversions and cost to decide which test is worth running.
FAQ
Can I calculate CTR without impressions?
You need impressions or enough compatible data to derive them. Clicks alone are not enough, and reach is not a substitute because it measures unique people rather than impression events. If the impression count is unavailable, leave CTR unavailable instead of estimating it from an unrelated metric.
Can I calculate CTR from CPC and CPM?
Yes, if CPC means cost per click and CPM means cost per 1,000 impressions, both use the same spend, scope, and period, and the values are valid and nonzero:
CTR (%) = CPM ÷ (10 × CPC)
For example, a hypothetical $20 CPM and $2 CPC imply 20 ÷ (10 × 2) = 1% CTR. This works because the shared spend cancels out. Prefer original clicks and impressions when available; rounded cost metrics can produce a slightly different result.
Tiny is a co-founder of Tomako, working across the full path from growth strategy to channel execution. His experience spans influencer marketing, affiliate marketing, SEO/GEO, and paid acquisition. As an indie maker and creator, he is especially interested in how small teams can make better growth choices with limited resources. On the Tomako Blog, he writes about channel decisions, practical execution, and lessons from building and growing products.
Tiny
