Change Image DPI Online
Set 72, 150, 300, or custom DPI for web and print. Optionally resize to maintain physical print dimensions.
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How to Change Image DPI Online
DPI (dots per inch) and PPI (pixels per inch) determine how large your image prints at its native resolution. A higher DPI means smaller, denser pixels and sharper prints. SmarterSources's DPI changer lets you set the exact DPI you need entirely in your browser, with no file uploads and no server processing.
DPI vs PPI: What's the Difference?
Technically, DPI refers to how many ink dots a printer places per inch, while PPI refers to how many pixels are packed into each inch of a digital image. In practice the two terms are used interchangeably when preparing images for print. This tool sets the PPI metadata embedded inside your PNG file, which printers and design software use to determine print size.
When Do You Need 300 DPI?
Professional printing standards require 300 DPI for sharp text and fine detail on paper. If you're submitting photos or artwork to a print shop, magazine, or book publisher, they'll almost always ask for 300 DPI files. For large-format prints like posters viewed from a distance, 150 DPI is often sufficient.
What About 72 DPI?
72 DPI is the historical screen resolution for Mac displays. On the web, DPI doesn't affect how an image appears on screen, since monitors display images pixel-for-pixel regardless of DPI metadata. However, some CMS platforms and print workflows check DPI metadata, so setting it correctly avoids warnings.
Resize vs. Metadata Only
This tool offers two modes. With "Resize to maintain print size" OFF, only the DPI metadata changes while pixel dimensions stay the same. This means the physical print size changes. With the toggle ON, pixel dimensions are recalculated so that the printed output stays the same physical size at the new DPI. For example, a 3000 x 2000 image at 150 DPI prints at 20 x 13.3 inches. If you set 300 DPI with resize on, the pixels stay 3000 x 2000 and the print size halves. If you set 300 DPI with resize on, the image is resampled to 6000 x 4000 pixels so it still prints at 20 x 13.3 inches.
Privacy Guarantee
SmarterSources processes your images entirely in your browser using the Canvas API and direct binary manipulation of PNG metadata. No files are ever uploaded to a server. Your images never leave your device.
Frequently Asked Questions
Does changing DPI change image quality?
If you only change the DPI metadata (resize toggle off), the pixels are untouched and quality is identical. If you resize to maintain print size, the image is resampled — upscaling can introduce softness, while downscaling is generally safe. For best results, start with the highest-resolution source image you have.
Why does my print shop say my image isn't 300 DPI?
Most images from cameras and phones have DPI metadata set to 72 or 96, even though the actual pixel count may be more than enough for 300 DPI printing. Use this tool to set the metadata to 300 DPI. If the pixel dimensions are also too low for the desired print size, enable the resize toggle to upscale.
Does DPI matter for web or screen display?
No. Browsers and screens render images based on pixel dimensions, not DPI metadata. A 1920 x 1080 image will look the same on screen whether it's tagged as 72 DPI or 300 DPI. DPI only matters when the image is sent to a printer or placed in a print layout application like InDesign or Illustrator.
What image formats are supported?
You can upload PNG, JPG, WebP, GIF, and BMP files. The output is always a PNG file with the DPI metadata embedded in the pHYs chunk. PNG is a lossless format, so your image quality is preserved perfectly in the download.
Can I set different horizontal and vertical DPI?
This tool sets the same DPI for both axes, which is the standard for virtually all print and web workflows. Asymmetric DPI is extremely rare and only used in specialized scientific or industrial imaging.