Coverage depends on the joint
Makers print coverage per bag for a joint width and a paver thickness. Alliance Gator gives 65 to 85 square feet per 50 lb bag for narrow joints and 22 to 42 for wide ones; Techniseal gives 60 to 120 and 25 to 40; SEK gives 50 to 75 square feet for joints up to 1/4 inch and 15 to 25 for 1/2 to 3/4 inch. Wider joints and thicker pavers take more sand.
The presets use the low end of each range, so you are less likely to run short. If your bag prints a figure for your paver and joint, enter that.
How wide are paver joints?
The Interlocking Concrete Pavement Institute says joints between concrete pavers are typically 1/16 to 3/16 inch wide. Measure a few joints on your patio before choosing a coverage figure.