Differences Between Conversion Counts in Google Ads and Analytics

One of the key challenges in marketing performance analysis is accurately comparing data across different platforms. Google Ads and Google Analytics 4 differ not only in how they measure conversions but also in the logic used to attribute value to individual events and in the way results are presented. This can lead to differing conclusions regarding campaign effectiveness. Understanding why conversions in Google Ads differ from those in Analytics allows marketers to better plan advertising strategies and manage budgets more efficiently. Below is a summary and explanation of the most important differences.

A significant factor contributing to discrepancies in reports is the attribution model used by each platform.

Google Ads, by default, uses a data-driven attribution model, which means the system analyzes actual user paths and assigns credit for conversions to individual touchpoints (ad clicks) based on their real impact on driving the conversion. For example: a user first clicks a Google Ads search ad, then visits the site the next day via organic search, and a few days later returns directly by typing the website URL into the browser, completing a purchase. In Google Ads’ data-driven model, the system considers only ad interactions and may attribute, for instance, 60% of the conversion credit to the Google Ads campaigns. This means that even though the last visit came via the direct channel, Google Ads determines that the ad had the greatest influence on the conversion and assigns the credit to the campaign.

In GA4, each report can use a different attribution model “last click,” “first click,” or “data-driven attribution” which often results in discrepancies.

Differences between GA4 reports:

• User acquisition report – uses the first click model, attributing the conversion to the first source the user interacted with, regardless of subsequent channels.
• Traffic acquisition report – based on the last click model, attributing the conversion to the most recent traffic source.
• Revenue (sales) report – uses a data-driven attribution model, analyzing the user journey and assigning conversion credit to channels based on their actual contribution to the purchase.

A conversion window is the period during which a conversion can be attributed to a previous user interaction with an ad or another traffic source. In other words, it defines the number of days from when a user clicks an ad (or views a video) to when they complete an action considered a conversion, such as making a purchase, submitting a form, or registering on a website.

In Google Ads, the default conversion window is 30 days, but it can be shortened (e.g., to 7 or 14 days) or extended up to 90 days. Conversions are attributed to the time of the user’s first interaction with the ad within the configured conversion window—regardless of when the actual purchase occurs.

For example, if a user clicks an ad on January 1st but completes the purchase on March 25th, the conversion will be attributed to the ad click date (January 1st), provided the campaign has a 90-day conversion window. As a result, Google Ads reports may update retrospectively over time, with conversion counts and revenue increasing as these “delayed” transactions are recorded.

In GA4, the default attribution window is also 30 days, but like Google Ads, it can be adjusted. The key difference lies in how conversions are assigned. In GA4, a conversion is recorded on the actual date the event occurs, not on the date of the ad interaction. For example:

• January 1st – the user clicks a Google Ads ad
• January 20th – returns via organic search
• January 25th – completes the purchase

The conversion will be recorded on January 25th, the day of the actual purchase. The attribution to a traffic source depends on the chosen attribution model and the length of the conversion window. If the January 1st ad click falls within the 30-day window, GA4 will include it in the conversion path and assign it its appropriate credit.

In the era of omnichannel marketing, users increasingly interact with multiple devices and platforms before completing a conversion.

Google Ads measures conversions primarily based on ad clicks, attributing them to a Google account if the user is logged into the same account across different devices. This means cross-device conversion tracking is only possible when Google can reliably link actions to a single user account, such as the same Gmail or Google account. If a user operates multiple accounts (e.g., personal and work), the system treats them as two separate individuals, and some conversions may not be attributed to the ad.

GA4 operates on an event-based model and uses various user identifiers, such as User ID, Google Signals, or Client ID. This allows GA4 to connect a single user’s activity even across multiple devices, provided there is a way to recognize them (e.g., they are logged into your website or Google Signals is enabled).

Although conversions imported from GA4 originate from the same data source, Google Ads processes them according to its own reporting and modeling rules. As a result, the number of conversions in Google Ads may differ from what is directly visible in GA4 reports.

Differences in data, such as the number of clicks, can also result from the filtering and protection mechanisms in each platform.

Google Ads automatically excludes clicks deemed invalid, such as those generated by bots, repeated clicks (when the same user accidentally clicks an ad twice before the page loads, navigates back in the browser and clicks the same link again, or refreshes a page with campaign parameters causing a duplicate click), or traffic considered suspicious. These interactions are removed from reports, preventing inflated click counts or campaign costs.

GA4, on the other hand, records all events that actually reach the system, unless the administrator has configured filters for internal traffic or bot exclusions. Unlike Google Ads, GA4 does not automatically filter such interactions at the system level, so in some cases, the number of clicks or events may be overreported.

If you use conversions imported from GA4 into Google Ads, keep in mind that data transfer and processing can take up to 48 hours. During this period, the number of conversions in the two systems may temporarily differ.

Differences in the number of conversions between Google Ads and Google Analytics 4 are a natural phenomenon, resulting from distinct tracking methods, attribution models, reporting approaches, and event interpretation. Google Ads focuses on measuring campaign performance in the context of ad clicks, whereas GA4 provides a broader view of user behavior and conversion paths.

For marketers, understanding these differences is crucial to correctly interpret results and optimize campaigns. In practice, the best approach is to use both tools simultaneously: Google Ads to evaluate the effectiveness of advertising campaigns and GA4 to analyze the full user journey and conversions across multiple channels. This approach enables a more comprehensive view of marketing performance and supports data-driven decision-making.