An improved system and method for optimizing online keyword auctions subject to budget and estimated query volume constraints is provided. A linear programming model of slates of advertisements may be created using estimates of the query volume for multiple time periods for use in generating a slate of advertisements that may represent a candidate set of advertisements in order of optimal revenue to an auctioneer. Upon receiving a query request, the slate generated by the linear program or a slate generated by dynamic programming may be chosen based on whether the weighted sum of prices for the slate of advertisements computed by dynamic programming may be within a factor of the weighted sum of the prices for the slate of advertisements computed by the linear program. The chosen slate of advertisements may then be served to accompany the search results of a query request to the web browser.