The easiest way is usually the Decimate modifier in Blender. It’s the quickest built-in method for lowering triangle count, and you can fine-tune the ratio until the model still looks acceptable.

Fastest workflow

  1. Select the object.
  2. Go to the modifier panel.
  3. Add Decimate.
  4. Use Collapse mode and lower the Ratio.
  5. Apply it only when you’re happy with the result.

Other useful options

  • Limited Dissolve works well if the mesh has lots of unnecessary edges, especially on hard-surface models.
  • Alt+J can convert triangles to quads in some cases, which may clean up the mesh but usually won’t cut the count as much as Decimate.
  • For best visual quality, make a low-poly version and bake normals from the high-poly model instead of just crushing the mesh.

Practical tip

If you’re working on a character or detailed asset, start with a mild Decimate ratio like 0.8 or 0.5 and check the shape as you go, since pushing it too far can damage important details.

TL;DR: Use Decimate modifier → Collapse → lower Ratio. That’s the easiest and most common way to reduce triangle count in Blender.