Why the Cut Line Is Magenta (M100 / CutContour)

2026-08-17

The magenta cut line convention explained: M100 in CMYK, R255 G0 B255 in RGB, stroke-only paths and how printers detect the contour.

The convention

Almost every sticker printer looks for a 100% magenta hairline path to identify the cut. In CMYK that is C0 M100 Y0 K0; in RGB workflows the equivalent is R255 G0 B255. Exports from this tool use exactly those values with a 0.3 mm stroke.

Spot colour names

• CutContour — the most widely recognised name (Roland, Summa, many print shops).
• Cut, Die Cut, Thru-cut — accepted variants; ask your printer which they parse.
• Magenta alone is usually enough because the RIP is configured to treat it as a cut.

Mistakes that break the cut

• Black or registration-colour cut lines get printed as artwork.
• Filled cut shapes hide the artwork underneath.
• Thick strokes (1 mm+) make the RIP guess the blade centre.
• Magenta used decoratively inside the artwork — recolour it or the plotter may cut through your design.

Verify in the PDF

Open the exported PDF, zoom to 400% and confirm the contour is a single closed magenta outline with no fill, sitting above the artwork. If your printer needs a named spot channel instead, tell them the path is M100 — they can map it in seconds.