Certain embodiments of the present invention are directed to test-duration estimation. A time needed to run an automated web-page test, or the remaining time needed to complete the automated web-page test, is estimated by estimating a sample size needed to ensure that observed differences in conversion rates are attributable, with a specified statistical significance, to selecting particular factor levels for particular factors that are varied during the automated testing. The estimated sample size is then divided by an average web-page access rate to obtain the remaining testing time to achieve a specified significance level.