ST_Buffer (Buffers / Proximity Shapes)

Use this skill when you need to create a polygon “buffer” around a geometry (point/line/polygon), typically for:

• proximity searches
• topology/contiguity validation
• “within X distance” visualization
• making thin lines easier to intersect (line → corridor)

Core rules

• Buffer units depend on the input type:
  • geometry buffers use the SRID’s coordinate units (degrees/meters/feet)
  • geography buffers use meters
• Do not buffer in EPSG:4326 degrees unless you intend degrees
• Prefer buffering in a projected CRS or using geography

Canonical patterns