Knee deep in a 3rd revision of a keyboard, trying to learn KiCad and everything else and realized I hadn't actually measured anything physically yet.

Standard key unit is 19 mm ± 1 mm. Grabbed a couple of the keys I plan on using and am getting around 18.11mm - 18.12mm at the base average.
Started measuring the footprints I have in KiCad and see they are 18.80mm end to end with a .25mm spacing in between.

Is this going to be okay or should I make my own footprints that are exactly 19mm ? Not really sure what the proper spacing between them should be.
Maybe I'm not measuring them in KiCad properly ?

Use module coordinate to determin key pitch.

"Pitch" is center-to-center or edge-to-edge distance, that is, the size of the key plus the space between (technically 2 half-spaces, each side).

Good ole Imperial measure, 3/4" is one standard unit.