The combined conversion rate cannot be obtained by simply averaging the percentages of two sources if the volumes differ. Add up the compatible goal-reaching visits and all visits, then divide the first sum by the second. First make sure the rows do not overlap and describe one goal in one period.
Training calculation
Suppose there were 100 visits from search, ten of which reached the goal. From the second source — 900 visits, nine goal-reaching. The segment conversion rates are 10% and 1%. Their simple average 5,5% is not the combined conversion rate.
The correct total for these non-overlapping visits: (10 + 9) / (100 + 900) × 100% = 1,9%. The second source provides more observations, so it has a stronger influence on the overall figure. All numbers are hypothetical; this is an example of arithmetic, not Boosted statistics.
Check the unit of the numerator
In Metrica terminology, conversion is the share of goal-reaching visits among all visits. If one visit contains three achievements of the same goal, do not substitute all three into the number of goal-reaching visits. If you are counting buyers among visitors, that is already a different metric with a different uniqueness rule.
In the table, label the goal, period, time zone, denominator, and filters. You cannot add purchases for a month to leads for a week or divide all actual payments by the portion of the audience that consented to tracking. The formula does not fix incompatible source data.
What to do with the total
Keep both the overall figure and the source rows. The combined conversion rate may decline solely because of a growing share of a less converting source, even if the work within each segment has not worsened. Before changing the offer, compare the traffic composition.
If the groups overlap, first obtain the total from the source visits with double counting excluded. Do not add up unique visitors by day as a monthly unique audience. If the necessary source numbers are unavailable, write "overall figure not calculated" instead of passing off the average of percentages as an exact result.
Diagram: 1 — 10 goal-reaching out of 100; 2 — 9 goal-reaching out of 900; 3 — 19 out of 1000, that is, 1,9%.
Related task: Zero orders after twenty clicks: what can be concluded from a small test.
Sources
Metrica: terms and definitions. Reviewed on 22 September 2026. Practical scenarios and diagrams are editorial methodology; the hypothetical numbers are not client data.
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