Offset Path in SVG: How Sticker Contours Are Built

2026-08-17

What an offset path is, how a sticker cut line is generated from an SVG outline, and why offsetting vectors is harder than adding a stroke.

Offset path vs stroke

A stroke draws a line of a given width centred on an existing path — it is a visual effect. An offset path is a brand new geometric outline that sits a fixed distance away from the original shape, and that new outline is what a cutting plotter follows.

This is why you cannot simply thicken your artwork outline and call it a cut line: the plotter needs one closed path at a real distance, not a thick decorative border.

How the offset is computed

• The artwork edge is traced into a polygon (marching squares over the alpha or background mask).
• A distance field is built from that polygon, so every pixel knows how far it is from the edge.
• The contour is re-traced at the requested distance, which grows or shrinks the shape evenly in every direction.
• The result is simplified (RDP) and smoothed into Bézier curves so the file stays small and the blade moves cleanly.

Why offsetting creates artefacts

Offsetting outwards merges narrow gaps: two letters 1 mm apart will fuse into one blob at a 2 mm offset. Offsetting inwards does the opposite — thin strokes disappear entirely at negative values.

Sharp concave corners are the other failure point. A true offset produces self-intersections there, which is why the generator resolves the geometry from the distance field instead of naively pushing points outwards.

Practical settings

• Text and thin elements: keep the offset small (1–2 mm) or expect letters to merge.
• Detailed illustrations: lower edge precision so the offset path does not copy every pixel wobble.
• Always inspect the exported PDF at 400% — self-intersections are visible as little loops.