Conversion rate
Also known as: CVR
In short
A percentage that relates recorded conversions or converting units to the eligible interactions, sessions or users defined by the measurement method.
Name both sides of the calculation
Conversion rate requires an outcome and a denominator. A purchase rate per session is not the same as conversions per ad interaction or the percentage of users who convert.
Google Ads defines its conversion rate using counted conversions divided by eligible ad interactions during the same period. Depending on the campaign, an eligible interaction can be more than a click. Multiple counted actions per interaction can produce a rate above 100%.
For a session-based business measure, explicitly define whether the numerator counts converting sessions or individual events. Those measures differ when a session contains several purchases or other actions.
Illustrative calculation
Imagine a fictional report with 80 counted purchase conversions and 2,000 eligible ad interactions. The conversion rate is 80 ÷ 2,000 × 100 = 4%.
A website report using 1,600 sessions would use a different denominator. Its result should not be compared as if it measured exactly the same population or counting rule.
Compare like with like
Align conversion definitions, attribution windows, dates and eligible traffic before judging a change. Allow recent conversions time to arrive. A higher rate can reflect a smaller, more selective audience or a change in counting configuration, so evaluate volume and business value alongside the percentage.