Print resolution: how big can your photo or file print?

"Is this file big enough to print?" is the most common question in printing, and the answer depends on two numbers: how many pixels the image has, and how far away people will be when they look at it. Once you understand that relationship, you can size any print with confidence.

PPI and DPI: not the same thing

PPI (pixels per inch) describes your file: how many image pixels are packed into each printed inch. It is the number you control.

DPI (dots per inch) describes the printer: how many tiny ink dots it lays down per inch. A printer might run at 1,200 or 2,400 dpi while printing a 300 ppi image, because it uses many ink dots to reproduce each pixel's color.

People say "300 DPI" when they mean 300 PPI all the time, and printers understand. But the number that matters for your file is pixels per printed inch.

The formula

Print size in inches = pixels ÷ ppi.

A photo 6000 pixels wide printed at 300 ppi is 20 inches wide. At 150 ppi it is 40 inches wide. Nothing about the file changes; you are only choosing how densely to spread its pixels.

How much resolution do you need?

The right ppi depends on viewing distance. The closer the viewer, the more detail their eye can resolve.

These are working targets, not hard limits. A good photo at 120 ppi will look better than a noisy, poorly focused one at 300.

Pixels to print size table

Use the pixel calculator for your exact file.

Why images from the web often print badly

Images on websites and social media are usually small (1,000 to 2,000 pixels wide) and heavily compressed. They look fine on a phone and soft on a poster. Images saved from messaging apps are often compressed again. For printing, always go back to the original file: the camera roll original, the photographer's full-size download or the designer's master file.

Remember copyright, too. An image you found online belongs to someone; get permission or use a licensed or public-domain image.

Raster vs vector

Photos are raster images, made of pixels, and the resolution rules above apply. Logos, type and illustrations made in design software can be vector, defined by shapes rather than pixels. Vector art prints sharp at any size, from a business card to a building wrap. Always supply logos as vector files where possible. Text in a layout is vector as long as it isn't flattened into an image.

What to do when your image is too small

1. Find a bigger original. This solves most problems.
2. Print smaller, or use it smaller. Place the photo in a smaller area with a solid background around it.
3. Accept a softer result for distant viewing. A banner seen from 30 feet forgives far more than a framed print.
4. Upscale carefully. Modern upscaling software can enlarge photos 2x with good results, sharpening edges and reducing blockiness. It adds pixels, but it can't recover detail that was never captured, and faces and text can look odd. Check a printed test.
5. Don't just change the ppi number. Changing "72 ppi" to "300 ppi" in an image editor without resampling only changes the print size label; the pixel count is the same.

Checking resolution in common tools

• Photoshop and similar: Image > Image Size shows pixel dimensions; uncheck "Resample" and type the print size to see the effective ppi.
• Layout apps (InDesign, Affinity Publisher): the links or resource panel shows "effective ppi" for each placed image at its current size.
• Online design tools: many show a warning when an image is too small for the print size; take it seriously.
• On a phone: photo info or details usually lists pixel dimensions.

Resolution and paper

Paper and finish change how detail shows. Glossy papers reveal more detail and more flaws; matte and textured fine-art papers soften slightly, so they are a little more forgiving. Canvas texture hides fine detail, so canvas prints look good at somewhat lower ppi. See poster paper types.

Resolution for scans of old photos and artwork

Scanning prints, slides or drawings to enlarge them follows the same math in reverse: choose a scan resolution that gives enough pixels for the size you want to print.

Higher scan resolution can't add detail the original never had, but it captures everything that's there.

Questions people ask

Is 72 dpi good enough for printing?

Ignore the label and look at pixel dimensions. A small 72 ppi web image is usually too small for print, but a large image labeled 72 ppi may be plenty once its pixels are spread at 150–300 ppi.

How many pixels do I need for a 24 x 36 inch poster?

For close viewing at 300 ppi, 7200 x 10800 pixels. At 150 ppi, which is fine for most wall posters, 3600 x 5400 pixels.

Can I print an iPhone photo as a poster?

Yes. A 12-megapixel phone photo (about 3024 x 4032 pixels) prints well up to around 16 x 20 inches, and acceptably to 18 x 24 inches viewed from a few feet away.

What resolution does a banner need?

Around 100–150 ppi at full size for most banners; large banners viewed from far away can go lower. Text and logos should be vector.

Does upscaling work for printing?

It can help with moderate enlargements, especially 2x, but it can't create detail that wasn't captured. Always print a test section before ordering a large print.

Sources and further reading

• Pixel density (PPI) explained
• Dots per inch (DPI) and how printers use it

Written and checked by K.R. for UnlimitedBanners.com. Product specs and prices change; confirm details with the printer or seller before you order. Spot an error? Tell us.