How to make an image 300 DPI

A form or printer wants 300 DPI. Work out the pixels you actually need, resize to them and change the DPI setting only when something really reads it.

By Utility Mule editorial team · Last updated September 30, 2026 · How we write guides

Printers, publishers and some application forms ask for images “at 300 DPI”. It sounds like a quality setting you could just switch on, but DPI (dots per inch) only says how densely to print an image’s pixels. What actually matters is whether the image has enough pixels for the size it will be printed.

Work out the pixels you need

Multiply the print size in inches by 300:

For centimetres, divide by 2.54 first: a 10 × 15 cm print is about 3.9 × 5.9 inches, so it needs roughly 1180 × 1770 pixels.

Check what you have

If your image already has at least that many pixels, it is good enough for a 300 DPI print, whatever its DPI label says. Most phone and camera photos have far more than enough for normal print sizes.

If it has many more, scale it down to the exact numbers with Resize image using Exact size. If the shape is different from the print size, crop first so nothing gets stretched: how to crop a photo to an exact size or ratio covers that.

If the image is too small

Enlarging a small image to the target pixel count makes it the right size, but it can’t add detail that was never captured, so it will print soft. Better options:

• Find the original: the camera file, not a copy saved from a chat or social network, which are usually shrunk.
• Print smaller. An image with 900 × 1200 pixels prints well at 3 × 4 inches.
• Ask whether 150 or 200 DPI is acceptable. For posters and anything viewed from a distance, it usually is.

When something really reads the DPI value

Most upload forms that mention DPI only check the pixel dimensions. A few, and some print shops, read the DPI value stored in the file. That value can be changed without touching the pixels:

• Mac: open the image in Preview, choose Tools → Adjust Size, untick Resample image and set the resolution to 300.
• Windows, Mac or Linux: in the free editor GIMP, use Image → Print Size and set the resolution to 300.

With resampling off, the pixels stay exactly as they were; only the label and the stated print size change. Our resizer changes pixel dimensions and doesn’t set the DPI label.

Still rejected?

If a form still refuses the image, the problem may be file size or format rather than resolution. Why won’t a website accept my photo? works through the common causes in order.