The HP-27S was a pocket calculator produced by Hewlett-Packard, introduced in 1988, and discontinued between 1990 and 1993 (sources vary).

The device featured standard scientific functions, including statistics and probability.

Business features included a real-time clock and calendar with up to ten appointments (each with a 22 character message string), as well as functions such as time value of money calculations.

[3] The 27S was not programmable in the conventional way, but it included an advanced formula-storage system with programming features.

An infra-red transmitter was also included, allowing the machine to be used with a compatible printer, such as the HP 82240B.