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How to work out print size and DPI from pixel dimensions

Before you send a photo to print, two questions matter: how big will it come out, and will it be sharp? Both come down to the relationship between pixels and DPI. This guide makes that relationship concrete.

The fastest way

Enter your image's pixel dimensions into the DPI & Print Size Calculator and it shows the physical size in inches and centimetres at 300 DPI (or any DPI you choose). You can also set a file's DPI header directly without re-encoding.

The one formula

Print size (inches) = pixels ÷ DPI. A 3000×2000 pixel photo prints 10×6.67 inches at 300 DPI, or 20×13.3 inches at 150 DPI. Multiply inches by 2.54 for centimetres. The calculator runs it in both directions, so you can start from a pixel count or from a target print size.

Why DPI is just metadata

DPI doesn't change the pixels — it's a label in the file header telling the printer how large to render them. Raising DPI on a small image can't invent detail; it just prints smaller. If you genuinely need more pixels, resample the image first with the Image Resizer, which changes the actual pixel dimensions.

Hitting a file-size limit too

If a print service or upload form also caps the file size, the Resize Image to KB tool gets a JPG or PNG at or below a KB limit while keeping the dimensions you need.

A note on privacy

The DPI & Print Size Calculator does both the maths and the DPI-header rewrite locally — your image is never uploaded.

Open the DPI & Print Size Calculator →

Common questions

What DPI do I need for printing?

300 DPI (dots per inch) is the standard for sharp photo and document printing, and 150 DPI is often acceptable for large posters viewed from a distance. To know whether your image has enough pixels, divide its pixel width by the DPI: a 3000-pixel-wide photo prints 10 inches wide at 300 DPI.

Does changing DPI change image quality?

No. DPI is only a number stored in the file's header that tells a printer how large to render the existing pixels — it doesn't add or remove detail. Raising DPI without adding pixels just prints the same image smaller; it can't make a low-resolution photo sharper. The calculator rewrites that header without re-encoding the image.

How do I convert pixels to inches or centimetres?

Divide the pixel dimension by the DPI: pixels ÷ DPI = inches, then multiply by 2.54 for centimetres. The calculator does this both ways, so you can enter a pixel size to get the print size, or a target print size to see how many pixels you need.

Is my image uploaded?

No. Both the calculation and the DPI-header rewrite happen entirely in your browser — your image never leaves your device.