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Seamless pattern checker

Check if a pattern is seamless before it goes to print. Drop in a tile and see it repeated, with any seam where the edges don’t meet found, marked and measured, and the size one repeat prints at. It runs in your browser, so the image never leaves your computer.

Free, no sign-upRuns in your browser

Seamless pattern

Runs in your browser. Your file stays on your computer.

How it works

How it works

  1. Your tile is repeated in a grid, with the place where four copies meet in the middle of the view. Zoom out to see the pattern as a whole, or in until you’re looking at the join pixel by pixel. Tick “Mark the tile edges” to see exactly where they meet.
  2. Both joins are measured: the right edge against the left, and the bottom against the top, colour by colour along their whole length and in strips.
  3. Each join is compared with the rest of the tile, not with a fixed number. A jump that would be normal in a busy texture counts as a seam in a smooth gradient, so grainy patterns aren’t flagged for their grain and soft ones are caught for a small break.
  4. You get a verdict: seamless, or a faint, visible or strong seam, on which edges and where along them, with how much bigger the jump is than anywhere else in the pattern.

It also gives the pixel size and the size one repeat prints at 300 ppi, sharp up close, and 150 ppi, for wallpaper and backdrops seen from further away. For any other size, use the DPI and print size calculator; for what those numbers mean, see DPI and raster images.

What makes a pattern seamless

  • Edges that carry on: whatever leaves the right edge comes back in at the left, at the same height, and the same for the bottom and top.
  • No light or colour drift: a shadow, vignette or gradient across the tile makes a step at every join, even when every motif lines up.
  • No border: exports and crops can leave a one-pixel line of white or a slightly different colour along an edge, which repeats as a grid.
  • Enough pixels for the repeat size: the tile is printed again and again at the same size, so its own resolution is what counts, not the size of the finished roll.

Questions

How do I check if a pattern is seamless?
Repeat it and look where the copies meet. Drop the tile in above and it’s shown repeated, with four tiles meeting in the middle of the view, and the checker measures the colour on each side of both joins: where the right edge meets the left, and where the bottom meets the top. If either jumps more than the pattern does anywhere else, it says where and how strongly.
Why does my pattern show lines when it repeats?
Usually because the edges were never made to match. The tile was cropped from a bigger picture, a gradient or shadow runs across it, a motif is cut off at one edge and doesn’t carry on at the other, or there’s a one-pixel border from the export. AI-generated patterns often have the first problem: they look like a pattern but weren’t built to tile.
How does it decide what counts as a seam?
It compares the jump across each join with the jumps between neighbouring columns and rows everywhere else in the tile. A busy texture jumps everywhere, so a little more at the join is no seam; a smooth gradient barely changes, so a small break at its edge is one. It looks at fine detail and at blurred-down versions of the tile, which catches a colour or light that drifts across a textured tile, and it checks the edge in strips, so a motif cut off over part of an edge is found and placed.
Is my image uploaded?
No. The image is read and measured inside your browser. To count your free checks we note that a check ran, the file type and how many edges had a seam, and your dashboard keeps those numbers with the pixel size. Never the image. Only if you ask us to make it seamless do we get the file’s name and what the check found, so we know what you’re asking about.
Do I need an account?
Yes, a free one: sign in with Google or an email link, with no password to remember. It asks when you drop in your first image, then checks that same image.
How big can a pattern repeat print?
Divide the pixels by the resolution. A 3000 × 3000 pixel tile prints a 10 × 10 inch repeat at 300 ppi, sharp enough for fabric or gift wrap seen up close, or 20 × 20 inches at 150 ppi for wallpaper or a backdrop seen from a step back. The repeat can be printed as many times as the roll allows; it’s the size of one repeat that the pixels limit. The DPI calculator works out any size.
What can’t it check?
Whether the pattern looks good repeated. A seamless tile can still show its grid if one motif stands out every time it comes round, and a half-drop or brick repeat needs its edges to match with an offset, which this doesn’t test. A line along the edge that is meant to be there, like the lines of a plaid, is reported as a seam, so look at the preview before you change anything.

Checking a finished print file rather than a pattern tile? Use the print-ready file checker. It reads PDFs and images for bleed, fonts, resolution and color.

Rather have it done? Print file fixing or Trade show booths & displays, at a fixed price.

More free tools

PDF, JPEG, PNG, TIFFPrint-ready PDF checkerCheck your PDF for print, freeCalculatorDPI and print size calculatorCheck an image’s DPI at print size, freePDFAdd bleed to a PDFAdd bleed to a PDF, free

Or the rest: Print template maker, Barcode generator: UPC, EAN, QR, Box dieline generator, Book cover size calculator, RGB and HEX to CMYK converter, Paper weight converter: GSM to lb, UPC and EAN check digit calculator, Label size calculator, and all of them on one page.

Seam in the repeat? We’ll make it seamless.

Send the tile and we’ll rebuild the edges so it repeats with no line, at a fixed price, usually the same day.

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