The delay between an ad interaction and the conversion it eventually produces. Because of lag, recent periods always look worse than they will once late conversions arrive, and any optimization decision made on the last few days of data is made on incomplete data. Google Ads reports conversions by the interaction date, so yesterday's numbers keep rising for weeks.
Related terms
Cite this entry:
Agency Echelon. "Conversion Lag." Agency Echelon Reference, reviewed September 2026. https://agencyechelon.com/reference/glossary/conversion-lag/