A G1M file is a data file saved in the G1M format used by various Casio graphing calculators, including fx-9860G, fx-9860GII, and fx-CG series calculators. It may contain various types of data, including an entire Casio Basic or C.Basic program or a single spreadsheet. G1M files are typically stored in the storage or main memory directories of a graphing calculator.

G1M files are most commonly used by older Casio graphing calculators from the 2000s and were replaced by G2M and .G3M files in newer versions of Casio graphing calculators. Since the files are not meant to be manually opened, you most likely will only encounter the files when transferring data files from or to the storage or main memory directories of a graphing calculator. The Casio FA-124 program allows you to transfer G1M files to your computer from a graphing calculator. The fx-Manager PLUS Subscription and fx-CG Manager PLUS Subscription programs also allow you to emulate fx- and fx-CG series calculators and open G1M files.