Seamless repeat checker
Drop in a tile and find out in a second whether it actually repeats. The checker measures block, half-drop, half-brick and step repeats, then tiles the image in the layout you pick, including mirror repeat, so you can see any seam for yourself. It runs in your browser, so nothing is uploaded and there is no sign-up.
Drop a tile here, or choose a file. Nothing is uploaded: the check runs in your browser.
Why a tile fails
Most tiles that fail were never built in repeat. They were cropped out of a larger artwork, which leaves the left and right edges unrelated to each other. It looks fine as a single square and falls apart the moment it is printed across a width of fabric, usually as a faint vertical line every tile, or a motif that is cut in half.
The second common failure is a near-miss: the artwork was built in repeat, then resized, sharpened or re-saved as a JPEG. Compression and resampling both change edge pixels slightly, and that is enough to produce a visible line on a large run even though the design is structurally correct.
Checking before press is cheap. Finding out after a rotary screen has been engraved is not, which is why this check belongs in prepress rather than at the end.
How the check works
- The first and last pixel columns are compared to test horizontal continuity.
- The first and last pixel rows are compared to test vertical continuity.
- For half-drop, the right edge is compared against the left edge shifted down by half the tile height; half-brick does the same across the tile width.
- For step repeats, the shifted edge moves by a third or a quarter of the tile instead of half, matching how a stepped layout actually tiles.
- Mirror repeat flips alternate tiles, so a mirrored seam meets its own reflection and is continuous by construction; only an unmirrored axis can still seam.
- The score is the mean colour difference across those edges, shown as a percentage of full scale.
This measures edge continuity, which is what makes a tile repeat. It does not judge whether the layout reads well across a width, whether motifs form unintended diagonal tracking, or whether the scale suits the end product. Those still need a designer's eye.
Frequently asked questions
Is the repeat checker really free?
Yes. It runs entirely in your browser, there is no account, no credit cost and no usage limit.
Is my design uploaded anywhere?
No. The file is read by your own browser and analysed on a canvas. It never leaves your computer, which means you can safely check client work and unreleased designs.
What counts as a clean repeat?
The checker measures the average colour difference between opposite edges of the tile. Under about 2 percent the seam is invisible in print, 2 to 6 percent is a minor seam worth fixing, and above that the join will be visible on fabric.
What is the difference between block and half-drop repeat?
In a block repeat, tiles line up in a straight grid, so the right edge must match the left edge exactly. In a half-drop, each column is shifted down by half a tile, so the right edge must match the left edge offset by half the tile height. The checker tests both.
What are step and mirror repeats?
A step repeat shifts each column down (or each row across) by a third or a quarter of the tile instead of half, which breaks up the grid more gently than a half-drop. A mirror repeat flips alternate tiles so each seam meets its own reflection, which makes any tile join cleanly on the mirrored axis. The checker previews both placements and scores the edges that still have to match.
My tile fails the check. How do I fix it?
A failing edge usually means the artwork was cropped rather than built in repeat. The repeat set tool rebuilds the artwork so opposite edges are continuous, and you can re-run this checker on the result.
Need to fix a failing repeat?
The repeat set tool rebuilds artwork so opposite edges are continuous, in block, half-drop, half-brick, step and mirror repeats.
See the repeat set tool →