A BASIC program is presented for two procedures that deal with constructing two-sided confidence intervals on means of normal populations with unknown standard deviations. One gives the sample size for a specified-length confidence interval for which the length and the probability (the tolerance) of not exceeding the given length are both chosen by the user. The other implements Stein's sampling rule to give the sample size for a confidence interval of user-specified length for which the probability (the tolerance) of not exceeding that length is 100 percent.