Sandpaper Grit Progression Calculator

How it works

Next grit ≤ current × jump factor (about 1.5, i.e. never skip more than ~50%), snapped to common grits, until the final grit is reached

Each sandpaper grit removes the scratch pattern left by the one before it. If you skip too far — say 80 straight to 220 — the fine paper can’t erase the deep 80-grit scratches, and they show up glaringly once finish goes on. The reliable rule is to jump no more than about 50% between grits (80 → 120 → 180 → 220), sanding each until the previous grit’s marks are gone. There is little point going finer than 180–220 for most film finishes, since the finish fills fine scratches anyway; oil finishes and bare wood can benefit from 320 or higher. Always sand with the grain on the final passes.

Worked example

Starting at 80 grit and finishing at 220 with a conservative ≈50% jump: 80 × 1.5 = 120, so go to 120; 120 × 1.5 = 180, go to 180; then 220. The schedule is 80 → 120 → 180 → 220 — four grits, three steps — with no jump large enough to leave scratches behind.

Frequently asked questions