# How do you un-triangulate a mesh?

I know that you can triangulate a selected portion of a mesh in Edit Mode by hitting CtrlT. This converts all quads and n-gons into tris. How how can this be reversed, combining coplanar triangles into quads and n-gons?

You can untriangulate the selected portion of a mesh by hitting AltJ. This will only create quads so some manual cleanup may be necessary if you need n-gons. You can do this by selecting the leftover edges and hitting X and clicking Dissolve Edges.

• This command is also available from the 3D view menus: Mesh > Faces > Tris to Quads – smashuu Jul 21 '17 at 21:17

You can use the decimate modifier using the planar option and apply it.

• This also turns them to n-gons while Alt J does not. Note that it likely won't work to set the Angle Limit to 0. – Keavon Jul 3 '14 at 14:44
• Note that this is the same as Limited dissolve in edit mode. – gandalf3 Jul 3 '14 at 19:49
• Note: this will most likely screw up your UV map. – Keavon Sep 15 '14 at 3:56

You can also do it through Blender's Python API if you want to get quads:

bpy.ops.mesh.tris_convert_to_quads()