For most DIY car paint jobs, sanding to around 400 grit before color is the safe, widely recommended sweet spot, with 320–600 grit being the usual workable range depending on product and condition of the car.

Quick Scoop

Core rule: what grit before paint?

  • For modern basecoat/clearcoat systems, 400 grit sanded surface is a very common professional recommendation to paint over.
  • Many painters work in the 320–400 grit range on primer or old paint when prepping for new color, especially with slightly thicker single-stage enamels.
  • If you feel 400 is a bit coarse, going up to 600 grit is generally considered acceptable for final sanding of primer before basecoat, as long as you still leave some “tooth” for adhesion.

A simple way to think of it: sand your primer or existing paint smooth with something in the 320–400 grit range, and don’t go much finer than 600 before you spray color, or you risk poor adhesion.

How it fits into the full sanding process

  • Heavy removal / bare metal: 40–80 grit for stripping thick old paint or rough shaping filler (not the stage right before paint).
  • Leveling and feathering: 120–180 grit to smooth scratches and refine filler work.
  • Primer shaping: 320–400 grit for sanding primer and getting panels straight before final prep.
  • Final prep before basecoat: 400–600 grit on primer or old clear/paint (often wet-sanded) right before spraying your new color.
  • After paint / clear: 1,000–2,000+ grit for wet-sanding runs, dust nibs, and polishing, not for initial adhesion.

Different viewpoints you’ll see in forums

  • Some pros insist on 400 grit only , arguing that going finer (like 800–1500) leaves too little tooth and can cause peeling later.
  • Others are comfortable with 600 grit as a final step, especially over well-primed surfaces, provided they use compatible products and good technique.
  • A few hobbyists try to sand to 800–1000 grit before paint for an ultra-smooth feel, but many paint trainers warn this can hurt adhesion unless the paint system explicitly allows it.

Example scenario

You’ve primed a repaired fender and want to repaint it:

  1. Block sand the cured primer with 320–400 grit until it’s straight and smooth.
  1. Finish-sand that same area with 400 grit (or up to 600 if your paint system allows) using wet sanding for a clean, even scratch pattern.
  1. Clean thoroughly, tack off, then spray your basecoat and clear over that 400–600 grit surface.

Key takeaways

  • “What grit sandpaper before painting car” → aim for about 400 grit , staying roughly in the 320–600 grit range depending on the products and whether you’re over primer or existing paint.
  • Don’t finish-sand for paint with ultra-fine grits like 1000–2000; save those for correcting and polishing after clear coat.

Information gathered from public forums or data available on the internet and portrayed here.