Image DPI Changer Calculator
Calculate what happens when you change an image's DPI. See new print sizes or required pixel dimensions. Understand the difference between metadata changes and resampling.
Quick Presets
Current Image
Target DPI
If enabled: resize pixels to keep physical size constant.
If disabled: only change DPI metadata, keep pixels the same.
Result
DPI Metadata Only
No resampling: The pixel dimensions stay exactly the same. You're only changing the DPI value in the file metadata.
Use when: You want to tell a printer how to interpret your pixels without actually changing the image data.
Warning: If your current DPI is very low and you just change it to 300 DPI without resampling, the image will print very small.
Resample (Interpolation)
With resampling: The image is recalculated to a new size, maintaining the same physical dimensions but at the new DPI.
Use when: You need to increase DPI for print and want the final image to be suitable for printing at that resolution.
Trade-off: Larger file size. Upsampling can cause slight quality loss. Downsampling loses detail.
Common Scenarios
Web Image to Print (72 DPI to 300 DPI)
You have a web image at 72 DPI. To print it at 300 DPI without changing its physical size:
Print Image to Web (300 DPI to 72 DPI)
You have a print image at 300 DPI. To display it on the web at 72 DPI:
Prepare for Print (Just Change Metadata)
You already have a high-res image at 72 DPI but it contains enough pixels for 300 DPI print.
What Happens When I Change DPI?
Two completely different things, depending on whether you tick 'resample'. Without resampling, changing DPI from 72 to 300 only updates a metadata tag in the file. The pixels stay identical. A 3840 x 2160 image at 72 DPI prints at 53 x 30 inches; the same file relabelled as 300 DPI prints at 12.8 x 7.2 inches. Same pixels, smaller print, sharper output. With resampling on, the calculator instead works out new pixel dimensions to maintain the original print size - which means inventing pixels that did not exist (a 72 DPI image resampled up to 300 DPI grows from 3840 to 16000 pixels wide, and looks soft).
The classic mistake is dragging a 1080 x 1080 Instagram graphic into Photoshop, changing the DPI to 300, and expecting it to print sharply at A4. With metadata-only change, the print just becomes 3.6 inches square (a postcard). With resampling, the image gets stretched up to 2480 x 2480 and looks blurry because Photoshop is averaging neighbouring pixels to invent new ones. Neither gives you a sharp A4 print - you needed the original at 2480 pixels wide in the first place.
When Should I Change DPI?
Change to 300 DPI (metadata only) when sending an image to a print shop. They will reject 72 DPI files even if the pixel count is enough, because their workflow software reads the DPI tag to lay out the print. Change to 72 DPI when exporting for web - it does not affect how browsers display the image (they ignore DPI entirely), but it shaves a few bytes off the file metadata.
Resample up (add pixels) only when you genuinely need more resolution and the source has been lost. Modern AI upscalers (Topaz, Magnific, even free options like Real-ESRGAN) do this far better than Photoshop's Bicubic resampling. Resample down (remove pixels) when emailing or uploading - the [image resizer](/image-resizer) and [image compressor](/image-compressor) handle this efficiently and let you preview file size savings before downloading.
DPI Settings for Common Tasks
Web and email: 72 DPI is the historic standard. The actual figure does not matter for screen display - it is purely a metadata tag. Print at home on a 600 DPI inkjet: 150 DPI source images give acceptable results, 300 DPI gives photo-quality output. Photo lab prints (5x7, 8x10, A4): 300 DPI is the spec. Large format posters viewed from over 1 metre away: 150 to 200 DPI is enough because viewing distance hides the lower resolution.
The calculator shows current physical print size, new physical size after a metadata-only change, and the pixel dimensions needed if you choose to resample to maintain physical size. It also estimates uncompressed file size in megabytes so you can see how much heavier the resampled version becomes. A 3840 x 2160 image at 72 DPI is 24MB uncompressed; resampled to 300 DPI to keep the same print size, it balloons to 415MB.
Frequently Asked Questions
Does changing DPI from 72 to 300 improve image quality?
Not by itself. If you only change the DPI metadata tag, the actual pixels are identical - the image just prints smaller. To genuinely improve print quality you need either more pixels (re-shoot, re-render, or AI upscale) or to print at a smaller physical size. Resampling up to 300 DPI at the original print size invents new pixels by averaging neighbours and the result looks soft.
Why does my print shop ask for 300 DPI?
Their layout and prepress software reads the DPI metadata to position the image on the print. A file labelled 72 DPI tells the software the image is intended for screen and may get rejected automatically, even if the pixel count is sufficient. Open the file in Photoshop or use this calculator to change just the DPI metadata to 300 - no resampling needed if your pixel count already matches the desired print size.
What is resampling and when should I do it?
Resampling means changing the actual number of pixels in the image. Resampling up adds invented pixels (always reduces sharpness). Resampling down throws away pixels (works fine if you do not need the original size). Use resampling down to make a 4K phone photo into a web-friendly 1500-pixel version. Avoid resampling up unless using an AI upscaler designed for that purpose.
How much bigger does the file get if I resample to 300 DPI?
If you resample a 3840 x 2160 image (72 DPI, 53 x 30 inch print size) up to 300 DPI while keeping the same print size, the image grows to 16000 x 9000 pixels. Uncompressed file size jumps from 24MB to 415MB. Even compressed as JPEG the file is 4 to 8 times larger. This is rarely worth it unless you are genuinely trying to print at billboard size.
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