Same-store sales is a business term which refers to the differential in revenue generated by a retail chain's existing outlets over a certain period (often a fiscal quarter or a particular shopping season), compared to an identical period in the past, usually in the previous year. By comparing sales data from existing outlets (that is, by excluding new outlets), the comparison is like-to-like, and avoids comparing data that are fundamentally incomparable. This financial and operational metric is expressed as a percentage.

Same-store sales are also known as comparable store sales, identical store sales or like-store sales.

Same-store sales are widely reported by publicly-owned retail chains as a key element of their operational results. For chains that are growing quickly by opening new outlets, same store sales figures allow analysts to differentiate between revenue growth that comes from new stores, and growth from improved operations at existing outlets.

By comparing how well existing outlets perform during a particular week compared to that same week in the previous year, business trends can be measured more accurately. Seasonal and geographical variations are removed from the measurement: instead of collecting an average over spans of time and location, annual changes in performance are revealed.