What are breakdowns in Meta Ads Reporting?

Three limits matter before you read one. Meta says that when using breakdowns for conversions, all conversions it isn't able to attribute will be shown as Uncategorised. For web and iOS app offsite conversions, it supports nine breakdowns only: age, gender, age and gender, country, impression device, platform, platform and device, placement and audience segments. You can combine different breakdowns, such as age with day, but not two under the same category, and for offsite conversions Meta limits combining to its delivery breakdowns with time or dynamic creative asset breakdowns.

Meta also says statistical modelling may be used in breakdowns to give a more complete measurement when conversion data may be missing or partial. And if you used Advantage+ audience suggestions for age, gender or detailed targeting, it says it will show ads to people matching your suggestion and other audiences when it's likely to improve performance. Its example is that if you suggest the gender Women, your ads could also deliver to men if Meta's AI finds them likely to respond.

Our reading, not Meta's: a breakdown describes where delivery went and what came back. It does not say what would have happened had the budget gone elsewhere, because the delivery system chose who saw each ad. Use it to find where to look, and an A/B test to settle a question.