Grapher Preview can open any GRF, GPJ, or GRT file created in Grapher v2 or later. If you have a Grapher v1 or Grapher DOS file, you can follow these instructions to convert it to a newer format.
Grapher Preview saves GRF, GPJ, and GRT files in the Grapher File (*.grf), Grapher Project (*.gpj), or Plot Template (*.grt) file format. Grapher Preview and Grapher can both open files in these formats. If you wish to open the file in an older version of Grapher (v10-v15), you can save GRF, GPJ, and GRT files back to those older file formats by clicking File | Save As, selecting the version you wish under Save as type, giving it a name, and clicking Save.
Note: If you open an older file in Grapher Preview and click File | Save, it will save it in the file format that it was created as. You must click File | Save As if you want to save as Grapher Preview file format.
Updated March 2020