PC-Size is a free DOS application that will run under Windows. It uses exact and approximate methods to calculate power. It will deal with samplesize/power calculations for t-tests, 1-way and 2-way ANOVA, simple regression, correlation, and comparison of proportions. The program will calculate effect size under the alternative with some input. There are three ways to calculate the alternative in this program: (1) by specifying individuals effects, (2) specifying a range and (3) specifying a ratio of variances. The non-centrality parameter of the appropriate distribution under the alternative is presented so that one can see how the effect size translates to these terms. Documentation comes with the executable.