Poster split

Ten millimetres is the default and a comfortable starting point for taping A4 or Letter sheets by hand. The Overlap field takes 0 to 50 mm and is a printed length: room for it is reserved on the sheet first, and only then is it converted into how much of the source page each tile covers, so the overlap measures the same on every tile instead of drifting from row to row. It is added to interior tile edges only, which means two neighbouring sheets each carry the band and share twice that width of duplicated image — plenty to lap and tape. Raise it to 15 or 20 mm for thick paper or a printer that feeds inconsistently. Ask for more than the sheet can hold and the tool refuses with a message rather than producing unusable tiles.

Tiles are written in reading order — left to right along the top row, then the next row down — with one tile per page of the output PDF. The Tile assembly preview numbers the grid in exactly that order, so tile 3 of a 3 × 3 poster is the top-right corner and page 3 of the file. If your source PDF has more than one page, every page is tiled with the same grid and the outputs run in sequence: all the tiles of page 1, then all the tiles of page 2. The status line multiplies it out before you build, so a 2-page file at 2 × 3 shows as 2 pages → 12 tiles. Printing the whole PDF in order therefore hands you the sheets in the order you will lay them out.

Lay the sheets out face up in the numbered order first, then work one seam at a time. Each sheet carries a small white margin plus the overlap band; trim the margin off the edge that will go underneath, slide it until the duplicated image in the overlap lines up with its neighbour, and tape along the seam. Working left to right across each row and then joining the finished rows keeps the cumulative error small. Because one scale and one orientation are used for the entire poster, every sheet prints at the same size and the seams genuinely match — but only if your print dialog is set to actual size, since "fit to page" or "shrink oversized pages" rescales individual sheets and quietly breaks the alignment.

Edge tiles are smaller because the overlap is only added on inside edges — there is nothing beyond the poster's outer boundary to overlap with. An interior tile in a 3 × 3 grid gains an overlap band on both sides, an edge tile gains one on a single side, and a corner tile gains one on each of its two inner sides. The tool keeps every tile at the same scale rather than enlarging the smaller ones to fill their sheet, so the printed image stays consistent across the whole poster; the smaller tiles are simply centred on their page with more white around them, and that extra white is the margin you trim before taping. Full-bleed sheets are not what this tool produces — it trades sheet coverage for assembly accuracy.

The preset chips cover 2 × 2, 2 × 3 and 3 × 3, and the Custom chip opens Columns and Rows fields that each accept 1 to 8 — up to 64 sheets per source page. A 1 × 8 or 8 × 1 grid is valid too, which is how you make a long banner from a strip. Every page in the source document is tiled with the same grid, so a 3-page PDF at 3 × 3 yields 27 sheets in one output file. Sheet size is A4 or Letter, and the orientation is chosen once for the whole poster — whichever way round makes the tiles largest — because rotating individual tiles would print rows at different sizes and the seams would stop lining up.

Poster split is free with no limit on how many posters you tile, and no watermark, logo or footer is added to any sheet. Each tile is a genuine clipped window onto your original page, re-embedded with pdf-lib, so text stays text and vector art stays vector — the tiles are not screenshots and will not blur when a large source is spread over many sheets. Nothing is uploaded: the page is read locally and the output PDF is assembled in your browser's memory before being saved. Big grids of a heavy source page use more memory than most tools here, since every tile references the same page, so on a phone stick to smaller grids and leave an 8 × 8 to a laptop.