Change Image DPI

1. 1Add the picture.
2. 2Choose Keep pixels to leave the image alone, or Resize pixels to hit a physical width.
3. 3Set the density — 300 DPI is what print shops usually ask for.
4. 4Download the result.

DPI describes how densely pixels are laid down on paper, not how good a picture is. The same 1200-pixel-wide photo prints four inches across at 300 DPI and sixteen inches across at 75 DPI, using identical pixels. This is why being told to send something at 300 DPI, with no size attached, is an incomplete instruction.

Keep pixels leaves the picture exactly as it is, which is the honest answer when the image already has enough detail for the size it will be printed. Resize pixels recalculates the image so that it measures the width you enter at the density you chose.

Enlarging cannot invent detail. Going from a 600-pixel-wide picture to something that needs 2400 pixels will look soft however the numbers are labelled, so start from the largest original you have.

Images are decoded by the browser, redrawn on a canvas and re-encoded on your own machine. Nothing is uploaded, so there is no waiting on a queue and no copy of your photos anywhere else.

• Work out the pixels you need: inches × DPI. A 6 × 4 inch print at 300 DPI needs 1800 × 1200 pixels.
• 300 DPI suits photographs viewed close up; posters seen from a distance look fine at 150.
• If your image already has enough pixels for the print size, choose Keep pixels and change nothing else.
• Start from the largest original you have; enlarging a small picture cannot add detail.

• What DPI means — and when 300 DPI actually matters
• How many pixels do you need for a 4×6, 5×7 or A4 print?
• Why an image goes blurry when you make it bigger