If you have ever been confused about resolution, you are in very good company. It is the question we answer most on our free file checks, and it is perfectly normal to find it baffling. Designers, marketing teams and couples planning a wedding all ask us the same thing: how sharp does my file need to be?
The short answer for large format printing in London: about 150 dpi at the finished size for most jobs, 300 dpi for things people read up close, and often less for giant pieces seen from far away.
Key takeaways
- DPI only means something at the finished print size, not on your screen.
- The further away people stand, the fewer dots per inch their eyes can see.
- Aim for about 150 dpi at full size for most large format work.
- Use 300 dpi for close up pieces like seating plans, canvas and acrylic photo prints.
- Hoardings and building wraps seen from a distance often print well at lower resolution.
- Vector logos and text stay sharp at any size, so only photos need checking.
What does DPI actually mean?
DPI stands for dots per inch. In everyday design talk people use it to mean pixels per inch: how many pixels of your image land in each inch of the finished print. The same photo can be high resolution on a postcard and low resolution on a banner, because the pixels are being stretched over a much bigger area.
That is why a number on its own tells you nothing. A 300 dpi file at A4 becomes a 30 dpi file if you blow it up ten times bigger. Always ask: how many dpi at the finished size?
Illustration: the same graphic from a high resolution file and from a small web image stretched to print size.
Why does viewing distance change the DPI you need?
Your eyes can only pick out so much detail. Hold a menu at arm's length and you can spot every soft edge. Stand three metres back from a backdrop and those same edges melt together. Walk across the road from a site hoarding and you could not count the pixels if you tried.
So big prints do not need the same pixel density as small ones. They need enough detail for the distance people will actually be standing.
Pro tip Before you worry about the number, ask where people will stand. That one answer usually settles the resolution question.
What DPI do you need at each viewing distance?
Here is the rule of thumb we use. It is a guide, not a law, and we check every file on its own merits.
| Where people stand | Typical pieces | Aim for |
|---|---|---|
| In your hand, under 1 m | Seating plans, menus, canvas and acrylic photo prints, place cards | 300 dpi |
| Across a room, 1 to 3 m | Posters, roller banners, backdrops, media walls, shell scheme panels | 150 dpi (our standard) |
| Across a site, 3 to 10 m | Hoardings, fascias, large PVC banners | Often fine below 150 dpi |
| Across the street or further | Building wraps and giant mesh banners | Often fine well below 100 dpi |
Rough guide only. Faces, fine text and products that people walk right up to still deserve more pixels, even on a big piece.
How many pixels does that mean for your print?
Multiply the finished size in inches by the dpi you need. Here are some common pieces worked out for you:
| Piece | Finished size | Viewing distance | Pixels needed |
|---|---|---|---|
| A2 poster | 420 × 594 mm | Close up, 300 dpi | 4,961 × 7,016 px |
| Seating plan | 600 × 900 mm | Close up, 300 dpi | 7,087 × 10,630 px |
| A0 poster | 841 × 1189 mm | Room distance, 150 dpi | 4,967 × 7,022 px |
| Roller banner | 850 × 2000 mm | Room distance, 150 dpi | 5,020 × 11,811 px |
| Backdrop | 3 × 2.4 m | Room distance, 150 dpi | 17,717 × 14,173 px |
| Hoarding run | 6 × 2.4 m | Street distance, 75 dpi | 17,717 × 7,087 px |
Don't panic about the big numbers. Your phone camera will not fill a 6 metre hoarding at 150 dpi on its own, and it doesn't have to. Large backgrounds, textures and colour fields are forgiving, and the bits that must be pin sharp, like logos and text, can be vector.
How do you check the resolution of your file?
- Find the pixel size. Open the image and note its width and height in pixels.
- Convert the print size to inches. Divide the finished width in millimetres by 25.4. A 1,000 mm wide print is about 39.4 inches.
- Divide pixels by inches. A 3,000 pixel wide photo across 39.4 inches gives about 76 dpi. Fine for a hoarding seen from the pavement, too soft for a seating plan read up close.
- Compare it with the viewing distance. Use the table above. If the number is well under what the piece needs, find a bigger original.
- Keep logos and text vector. Vector artwork has no dpi limit. Our guide to vector files explains how to spot one.
- Send it for a free check. Not sure? Send the file anyway. We check resolution on every job before anything prints.
Can you build artwork at 1:10 scale?
Yes. For hoardings and very large backdrops, building the file at full size can make it huge and slow to work with. Set it up at 1:10 scale, tell us, and we scale it up at print. Our artwork guide covers the setup.
Works perfectly at 1:10
- Vector logos, shapes and text
- Flat colour backgrounds
- Simple gradients
Needs extra pixels at 1:10
- Photos and textures, which need ten times the resolution in the scaled file to land at 150 dpi full size
- Screenshots and web images, which are usually far too small
Pro tip If a photo is the hero of a giant print, send us the original from the camera or photo library, not a version saved for the web or sent over a messaging app.
What if your image is too small?
It happens all the time, and there is usually a way round it.
- Find the original. Images sent by email, social media or chat apps are often shrunk along the way.
- Redraw the logo as vector. Our in house design team can redraw a fuzzy logo so it prints razor sharp.
- Make the photo smaller in the layout. Let colour, pattern or text fill the space and give the photo a size it can handle.
- Choose a stock image at full resolution. Buy the largest size available.
- Ask about AI upscaling with care. It can help some images, but it can also invent odd details. Our AI artwork guide explains what to watch for.
Resolution is one half of a great print. The other half is colour. If your file is RGB we can convert it to CMYK, but there is a possibility of colour change, so read CMYK vs RGB explained before you send it.
Send it over and we'll tell you if it's sharp enough
You don't need to become a resolution expert. Every job at Print Station gets a free artwork check before it prints, so we'll spot a soft image long before it ends up on your banner, backdrop or hoarding.
