How to make a collage for printing
- Pick the paper. 6 × 4 or 4 × 6 in for a lab print, 5 × 7 for a card or frame, A4 for a home printer. They lead the size list.
- Open the photos. Use the originals from your camera or phone, not copies forwarded through a messaging app, which are often too small to print.
- Keep inside the trim line. The dashed line is 3 mm in from the edge. Labs trim unevenly; keep faces and text inside it. The Style step shows the outer edge in millimetres.
- Read the sharpness. The Save step lists each slot's pixels per inch. Below 150 it says the slot may look soft and the stage badges it.
- Save as JPG or PDF. The JPG carries 300 pixels per inch in its header; the PDF is one page at the paper size with that JPG inside, so it prints at size without a scaling dialog.
The arithmetic of a sharp print
A print looks sharp at arm's length at around 300 pixels per inch and starts to look soft below 150. So a 5 × 7 in collage is made at 1500 × 2100 pixels, and an A4 one at 2480 × 3508. For each slot this page works out how many of your photo's own pixels end up across each printed inch: the pixels across the part of the photo the slot shows, divided by the slot's width in inches. A twelve-megapixel phone photo in half a 5 × 7 page prints at well over 300; a 640-pixel photo saved from a chat, in a slot five inches wide, prints at about 128, and is flagged.
A 1080-pixel square made for posting prints cleanly at only about 3.6 inches across, which is why the print sizes exist at all.
| Size | Pixels | At 300 ppi |
|---|---|---|
| 6 × 4 in | 1800 × 1200 | Lab print, landscape |
| 4 × 6 in | 1200 × 1800 | Lab print, portrait |
| 5 × 7 in | 1500 × 2100 | Card or frame |
| 7 × 5 in | 2100 × 1500 | Card, landscape |
| A4 | 2480 × 3508 | Home printer |
| A4 landscape | 3508 × 2480 | Poster or board |
Why the PDF and the density matter
A JPG from a browser says nothing about its physical size, so a print shop or a word processor guesses — often 72 or 96 to the inch — and the collage comes out huge or tiny. This page writes 300 pixels per inch into the file's header, so it opens at the right size. The PDF goes one step further: it is one page of exactly the paper size with the JPG placed on it byte for byte, without being compressed a second time.
The trim line is drawn on the stage only; it never appears in the file.
Questions people ask about this one
What resolution should a printed collage be?
300 pixels per inch is the usual target. This page makes print sizes at 300 and warns when a photo in a slot falls below 150.
Can I print a collage on A4?
Yes. A4 is 2480 × 3508 pixels, or a one-page A4 PDF.
Why does a slot say Soft in print?
The photo in it has too few pixels for that slot at that paper size. Use the original photo, a smaller slot, or a smaller paper size.
Do I need bleed?
Not for most lab prints. Keep important things inside the 3 mm trim line. A PDF with crop marks and bleed for print shops is not built yet.
Is my collage uploaded to be printed?
No. This page makes the file on your device; you take it to the printer yourself.
Where to go next
- Print a collage without soft photos or clipped edgesCalculate print pixels, bleed, margins and image resolution before exporting a collage.
- Wedding collageA gallery mount, a serif title and a ring.
- Family collageOne photo of everyone and up to twenty-nine more round it.
- Up to thirty photosGenerated layouts for 13 to 30 photos, A4 first.