Written by Krisztián Stark
Key takeaways
- A conversion window sets how long after an ad interaction a conversion can still be credited to that ad.
- Longer windows credit more conversions to ads and shorter ones credit fewer, so compare channels only with matching windows.
- Set the window close to how long your customers really take to decide, and check the time lag in your reports before changing it.
What is a conversion window?
A conversion window is the period after someone clicks or views an ad during which a conversion, such as a purchase, sign-up or install, can still be credited to that ad. If the window is 30 days and a person buys on day 12 after clicking, the sale counts for the ad. If they buy on day 31, it does not. The same idea goes by other names: attribution window, lookback window, or click-through window.
The window does not change what people do. It changes what your reports say about why they did it, and so it changes your cost per conversion, your ROAS, and which campaigns look like winners.
How a conversion window works
Every ad platform records the moment of the interaction, a click or an impression, and later receives a conversion event, usually from a tag, an SDK or a postback. It then asks two questions: did this person interact with one of our ads, and did the conversion happen within the window after that interaction? Only if both answers are yes does the platform count it.
Most platforms keep separate windows for different interactions:
- Click-through window: how long after a click a conversion counts. This is usually the longest one.
- View-through window: how long after an ad was seen, without a click, a conversion counts. It is usually short, because seeing an ad is weaker evidence than clicking it.
- Engaged-view window: some video platforms add a middle case for people who watched a set part of a video without clicking.
The window is not the same as attribution itself. Attribution decides which ad gets the credit when several ads touched the same person; the window decides which interactions are still recent enough to be considered at all.
Conversion window defaults on major platforms
Defaults differ, which is one reason the same campaign can report different numbers in different tools. These are taken from each company’s own help pages:
| Platform | Default window | Adjustable range |
|---|---|---|
| Google Ads | 30 days after a click; 3 days for engaged views; 1 day for view-through | 1 to 90 days for clicks, depending on the conversion source; engaged views 1 to 30 days |
| Google Analytics 4 | 30 days for acquisition key events (first_open, first_visit); 90 days for all other key events | 7 days for acquisition events; 30 or 60 days for others |
| Adjust (mobile attribution) | 7 days from engagement to install when matching by device identifier; 24 hours for impression-based attribution | Clicks 1 to 30 days; impressions 1 to 24 hours |
Google Ads recommends a window of at least 7 days for Search and Display campaigns to get richer conversion data. Mobile measurement partners work on the same principle for installs; What is an MMP? explains lookback windows in app campaigns in more detail.
Why the length of the window matters
A longer window credits more conversions to your ads, and a shorter one credits fewer. Neither is automatically right. Too short, and you undercount ads that start a slower decision, such as a software trial someone thinks over for two weeks. Too long, and you credit an ad for a purchase the person would have made anyway, weeks after they forgot about it.
Illustrative: one month of sales under a 7-day and a 30-day window
Say a campaign costs $600 in a month and 40 buyers clicked one of its ads. Of those, 24 bought within 7 days of the click and 16 took between 8 and 30 days. With a 7-day window the report shows 24 conversions at $25 each; with a 30-day window it shows 40 at $15 each. Same ads, same buyers, same money. These figures are invented to show the effect, not typical results.
The practical rule follows from that example: never compare two channels, or two periods, measured with different windows. A channel reporting on 30 days will always look cheaper than one reporting on 7 days.
How to choose a conversion window
- Look at your real time lag. Many ad platforms can show how many days pass between the click and the conversion; Google Ads calls it the time lag report. Choose a window that covers the bulk of it.
- Match the window to the action. An app install or a free sign-up usually happens within hours or a few days. A high-priced purchase or a business sale can take weeks.
- Keep view-through windows short, or leave them out of decisions about budget, because a view is weak evidence.
- Use the same window everywhere you compare, including in the spreadsheet where you add up CAC, CPA and LTV.
- Change it rarely. A new window breaks the comparison with every earlier period, so note the date of any change.
Conversion window vs approval window and other time limits
In pay-per-result advertising and offerwalls you will meet other clocks that are easy to confuse with a conversion window:
- Time to complete an offer: how long a user has, after starting an offer, to finish it and have it count.
- Approval window: how long an advertiser has to approve or reject a reported result before it is approved automatically.
- Pending period and reversals: how long a publisher’s reward stays pending, and whether a credited result can later be reversed. Handling missing reward tickets covers what this means for publishers when a user says a reward never arrived.
A conversion window answers “which ad gets the credit?”. These other limits answer “is this result final, and who pays for it?”.
The two clocks on a Sharklio task
Sharklio does not use a click or view attribution window, because it does not guess which ad caused a conversion. A task campaign pays for a completion the user proves directly. A user has 24 hours from starting a task to send the proof, and a click campaign visit must be finished within an hour. Then the advertiser’s approval window runs, from 30 minutes to 3 days, and anything not reviewed in time is approved automatically. Choosing the right approval window explains the trade-off. Sharklio has not launched yet; leave your email and we will tell you when it opens.
Frequently asked questions
Is a conversion window the same as an attribution window?
In practice, yes. Both names describe how long after a click or view a conversion can still be credited to an ad. Mobile tools often call it a lookback window.
What is the default conversion window in Google Ads?
30 days after a click, according to Google’s help page, with 3 days for engaged-view and 1 day for view-through conversions. The click window can be set from 1 to 90 days, depending on the conversion source.
Should I use a 7-day or a 30-day conversion window?
Use the one that matches how long your customers take to convert. Quick actions such as installs or free sign-ups fit a short window; considered purchases need a longer one. Whichever you pick, use it consistently.
Does changing the conversion window change past data?
It depends on the platform. Google’s help page says a change in Google Ads applies to all conversions going forward, not to earlier ones. Either way, compare periods only when they use the same setting.
What is a view-through conversion window?
The period after someone saw an ad, without clicking it, in which a conversion still counts for that ad. It is usually much shorter than the click window, often one day.
