Comparing Conversion Rates: Last 30 Days vs. Previous Year

Romane T. · 2025-10-02T09:54:48.975Z

I want to compare the conversion rate of the 30 last days with the one from the previous year. I chose a booking window of 30 days. When I chose the dates of 30 last days, does it imply that my conversion rate will be artificially low because many conversions did not happen yet or not ?

Yes, if you select the "Last 30 days" as your date range and your funnel's conversion window is also 30 days, your conversion rate may appear artificially low. This is because users who entered the funnel toward the end of the selected period may not have had enough time to complete all funnel steps within the 30-day conversion window. As a result, some conversions that will eventually happen are not yet counted in the report, leading to an underestimation of the true conversion rate for that period.This effect is especially important when comparing recent periods (like the last 30 days) to older periods (such as the same 30-day window from the previous year), where all users have had the full conversion window to complete the funnel. The documentation notes that the date window selected might still fall under the conversion window, and more conversions have yet to come through, which can impact your analysis results Docs / Reports Overview / Find Interesting Segments.To avoid this issue, consider analyzing a date range that ends far enough in the past to ensure all users have had the full conversion window to convert, or be aware of this limitation when interpreting your results.

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