Set the DPI (print resolution) of JPG, PNG and BMP images to 300, 72 or any value. Only the resolution tag is rewritten, so the pixels and quality stay exactly the same, and you see the print size before you download.
New DPI
DPI
Print size calculatorTry it before adding a file
File
Pixels
Current DPI
New DPI
Print size
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How to use the Image DPI Changer
Add images: drop JPG, PNG or BMP files on the box or click Choose images. You can add many at once.
Pick the DPI: click a preset such as 300 or type your own value. To print at a set size, switch to Print width and enter the width in inches or centimeters.
Check the table: it shows each file's pixel size, current DPI, new DPI and the print size it will have.
Download a single file with its Download button, or press Download all to get every image (as a ZIP when there is more than one).
DPI, pixels and print size
An image file stores pixels; the DPI value only says how big those pixels should be on paper. The formula is simple:
That is why changing the DPI is lossless: the same pixels are just spread over a smaller or larger area. If you need more detail at a large print size, you need more pixels, not a higher DPI number.
Pixels needed for common print sizes at 300 DPI
Print size
At 300 DPI
At 150 DPI
2 × 2 in (5.1 × 5.1 cm)
600 × 600 px
300 × 300 px
4 × 6 in (10.2 × 15.2 cm)
1200 × 1800 px
600 × 900 px
5 × 7 in (12.7 × 17.8 cm)
1500 × 2100 px
750 × 1050 px
8 × 10 in (20.3 × 25.4 cm)
2400 × 3000 px
1200 × 1500 px
A4 (8.27 × 11.69 in)
2480 × 3508 px
1240 × 1754 px
US Letter (8.5 × 11 in)
2550 × 3300 px
1275 × 1650 px
A3 (11.69 × 16.54 in)
3508 × 4961 px
1754 × 2480 px
Which DPI should I use?
300 DPI: the usual requirement for photo prints, magazines, books and print-on-demand.
150 to 200 DPI: posters and large prints viewed from a distance.
600 DPI: line art, scanned documents and sharp text.
72 or 96 DPI: screens and the web, where the DPI value is ignored and only pixels matter.
Where the value is stored: JPG files keep it in the JFIF APP0 header (and often again in EXIF and Photoshop blocks), PNG files in the pHYs chunk as pixels per meter (300 DPI = 11,811 px/m), and BMP files in the header, also in pixels per meter.
Frequently asked questions
Does changing DPI reduce image quality?
No. This tool only rewrites the resolution value stored in the file header. The compressed image data is copied byte for byte, so the pixels, colors and file quality are exactly the same as before.
Will changing the DPI make my image sharper or bigger?
No. DPI only tells printers and layout programs how many pixels to place per inch. A 1500 x 1500 pixel photo set to 300 DPI prints at 5 x 5 inches; set to 150 DPI it prints at 10 x 10 inches with larger, softer pixels. The pixel count does not change. To add pixels you need to resize or upscale the image.
How do I convert an image to 300 DPI?
Add the image, click the 300 preset and press Download. The file now reports 300 DPI to Photoshop, Word, InDesign and print shops. If you also need a minimum print size at 300 DPI, check that the image has enough pixels: width in inches x 300.
What is the difference between DPI and PPI?
PPI (pixels per inch) describes how densely an image's pixels are placed when printed or displayed, and DPI (dots per inch) strictly describes printer ink dots. In image files and most software the two words are used for the same stored value, which is what this tool changes.
Why does my image still show 72 DPI in some programs?
Some programs read a different field than others. This tool updates the JFIF header and, when they exist, the EXIF and Photoshop resolution fields of JPG files, and the pHYs chunk of PNG files. A few web browsers and viewers ignore DPI entirely and always assume 72 or 96.
Which formats are supported?
JPG/JPEG, PNG and BMP, which all have a standard place to store resolution. WEBP and GIF have no standard DPI field, so convert them to PNG or JPG first if you need a DPI value.
How do I calculate print size from pixels and DPI?
Print size in inches = pixels / DPI. Multiply by 2.54 for centimeters. For example, 2400 x 3000 pixels at 300 DPI prints at 8 x 10 inches (20.3 x 25.4 cm).