JIS, CAMI, and FEPA grit numbers measure different things. Convert between systems by actual particle size.
Values are approximate. Grit systems measure particle size differently and manufacturers vary, so treat matches within about 20 percent as equivalent in practice.
A JIS 1000 waterstone runs around 11 to 15 microns. CAMI 1000 sandpaper is closer to 5 microns, roughly the territory of a JIS 3000 stone. Buy sandpaper for the scary sharp method using the JIS column above, not the printed number, or your progression will jump wildly.
| Range | Micron | Job |
|---|---|---|
| JIS 220 to 400 | 60 to 37 | Repair chips, reset bevels |
| JIS 800 to 1500 | 18 to 10 | The everyday sharpening zone |
| JIS 3000 to 6000 | 5 to 2.5 | Refine and polish, kitchen sweet spot |
| JIS 8000+ | under 2 | Mirror edges, razors, show polish |