⚡ 10-second version
You have a home printer that does A4 and you want a poster a metre tall. tooladda.online/poster-printer.html slices your image into page-sized tiles, adds glue overlaps or trim marks, and hands you one PDF. Print, cut, join.
❗ Important
Your image is read and sliced in your browser. Nothing is uploaded — which matters if you're printing artwork you own, a client's design, or a photo of your family.
📐 The arithmetic that decides if your poster looks good
Two numbers make or break a tiled poster, and neither is obvious.
How many pages?
A4 is 210 × 297 mm, but you can't print to the edge — most printers need ~5 mm margins, and a glue overlap eats a bit more. Call the usable contribution per page 190 × 277 mm with a 10 mm overlap.
For a 1000 × 700 mm poster:
columns = ceil(700 ÷ 190) = 4
rows = ceil(1000 ÷ 277) = 4
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16 A4 pages
Is your image big enough?
This is where most tiled posters fail. Printing that same 1000 × 700 mm poster at 150 DPI requires:
1000 mm ÷ 25.4 × 150 = 5906 px
700 mm ÷ 25.4 × 150 = 4134 px
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≈ 24 megapixels
Feed it an 800 × 600 phone screenshot and no software on earth will save it — you'll get a beautifully aligned mosaic of blur. 150 DPI is fine for a wall poster viewed from a metre away; 300 DPI is only worth it if people will stand close.
| Poster size | Min pixels @150 DPI | Pages (A4, 10 mm overlap) |
|---|---|---|
| A2 (420 × 594 mm) | 2480 × 3508 | 4 |
| A1 (594 × 841 mm) | 3508 × 4967 | 9 |
| 1000 × 700 mm | 5906 × 4134 | 16 |
| A0 (841 × 1189 mm) | 4967 × 7022 | 20 |
🧭 How it works
✨ What's inside
| ### 📄 Four paper sizes A4, A3, Letter and Tabloid — portrait or landscape. Landscape tiles often need fewer pages for a wide image, and the tool shows you the count before you print. | ### 🧴 Glue overlap **or** trim marks Overlap mode leaves a strip to paste over the neighbouring tile (forgiving, slightly visible seams). Trim mode gives cut marks for a butt join (invisible seams, needs a steady hand). |
| ### 🔢 Live page count Change the target size and the grid updates instantly. You find out it's 40 pages *before* you commit your ink cartridge. | ### 🏷️ Tile numbering Each page labelled with its row and column, so a stack of 16 identical-looking sheets can actually be assembled. |
| ### 📄 Single PDF output One file, correct page order. No folder of 16 PNGs to print one at a time. | ### 🔒 Fully client-side No upload, no watermark, no size cap imposed by someone's server bill. |
🛠️ What people print with it
| Situation | Result |
|---|---|
| 🎉 Party or event banner | A birthday or wedding banner from a home printer for the price of paper. |
| 🏫 Classroom wall chart | A big periodic table, map or number line without a plotter. |
| 🗺️ Large map for planning | A trek route or site plan at a size you can actually annotate. |
| 🎸 Band / film poster | Enlarge artwork for a room without a print shop. |
| 📐 Full-size templates | Woodworking, sewing or CNC patterns printed 1:1 across pages. |
| 🖼️ Multi-panel wall art | Deliberately visible panel gaps, mounted as a triptych. |
📖 Print it properly — five steps
1. Open → tooladda.online/poster-printer.html
2. Drop → your highest-resolution image (check the DPI table above)
3. Set → target poster size, paper size, overlap mode
4. Review → the page count and grid preview
5. Print → PDF at 100% scale — NOT "Fit to page"
▶ Start tiling — tooladda.online/poster-printer.html
⚠️ Warning
The one setting that ruins everything: printing with "Fit to page" / "Shrink to fit" enabled. Your printer will scale each tile by a percent or two and no two edges will ever line up. Set scale to 100% / Actual size in the print dialog every single time.
💡 Tip
Print one tile first as a test. One wasted sheet is cheaper than discovering the scaling problem on sheet 16.
❓ FAQ
Is it free? Watermark?
Free, no watermark, no page limit, no signup.
My poster came out blurry. Why?
The source image didn't have enough pixels for the size you asked for. Use the DPI table above: at 150 DPI a 1-metre poster needs roughly 5,900 pixels across. No amount of software can invent detail that was never captured.
Why don't my tiles line up?
Almost always "Fit to page" in the print dialog. Set scale to 100%. If they still drift, your printer's margins differ from the assumed value — increase the overlap slightly to absorb it.
Overlap or trim marks — which should I pick?
Overlap if this is your first tiled poster; it hides small alignment errors. Trim marks if you want invisible seams and are comfortable cutting straight.
Can I print on A3?
Yes. A3 roughly halves the page count versus A4 for the same poster.
Is my image uploaded?
No. It's read locally and sliced on a canvas in your browser.
How do I join the tiles neatly?
Work left to right, top row first. In overlap mode, glue the overlap of the right-hand tile under the left one so the seam faces away from the viewing direction — it catches far less light that way.
🔬 Under the hood
- Canvas-based slicing in vanilla JavaScript — no server round-trip, no framework.
- Grid maths accounts for printable area and overlap, so the page count you see is the page count you print.
- Multi-page PDF assembled client-side at your chosen paper size.
- Offline-capable PWA with a service worker.
Originally published on ToolAdda, where Poster Printer runs free in your browser — nothing is uploaded, nothing leaves your device.
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