What is ROAS?

ROAS answers 'for every unit of currency I spent, how much revenue came back?'. A ROAS of 3 means $3 of attributed revenue per $1 of spend. It is a platform-reported, attribution-dependent number, so the same ads can show different ROAS in Meta, Google, and your store depending on the attribution window and model. Read it alongside a business-level efficiency metric like MER, never on its own.