Short answer
A Conversions campaign needs conversion tracking through the Pixel, Conversions API or both, and at least one supported standard event such as purchase, sign-up or lead. Each campaign optimises to one event that can't be changed. You choose click billing (pay per valid click) or impression billing (pay per 1,000 impressions); you never pay per conversion.
Click vs impression billing
| Billing | You pay for | Optimises toward |
|---|---|---|
| Clicks | Valid clicks | Conversions after a click |
| Impressions | Impressions | A broader set, including view and click conversions |
Before you switch
- The event must fire often enough; rare events make results hard to judge
- Give the campaign enough time and budget
- To change billing, clone the campaign
Questions
Can we optimise for a custom event?
No. Custom conversion events aren't supported for optimisation.
Facts checked against the sources below on 12 October 2026. Platforms change quickly: if something here no longer matches what you see, tell us and we will update it.
