How to change the DPI of an image
- Drop one or more JPG or PNG images. The table shows each image's pixel size and current DPI (if it has one).
- Enter the DPI you need, such as 300 for print or a form that asks for "300 dpi".
- Check the resulting print size, then download. The new file has exactly the same pixels; only the resolution tag changes.
What DPI really means
DPI (dots per inch), or PPI for digital images, is a number stored in the file that tells printing software how large to print the picture. It does not change the image itself. A 3000 × 2000 pixel photo has the same detail whether it is tagged 72 or 300 DPI: at 300 DPI it prints at 10 × 6.7 inches (25.4 × 16.9 cm), at 72 DPI the software would print it at about 42 × 28 inches. Many print shops, publishers and online forms ask for "300 DPI" files, and often just check the tag, which is exactly what this tool sets.
For JPEGs, the setting is written to the standard JFIF header (added if the file does not have one); for PNGs, the pHYs chunk is written or replaced. Neither method recompresses the image, so there is no quality loss. If you need more pixels for a big print, you would have to resize (upscale), which cannot add real detail. Everything happens in your browser; files are never uploaded.
Does changing DPI reduce quality?
No. The pixels are copied unchanged; only the resolution tag is updated.
How many pixels do I need for a 300 DPI print?
Multiply the print size in inches by 300: a 6 × 4 inch print needs 1800 × 1200 pixels.
Why does my image show 72 DPI?
Many apps and screenshots save 72 or 96 DPI by default, or no DPI at all. It does not affect screen display.