Free tool
What does a scan actually produce?
Pick the print and the DPI. See the pixels, the megapixels, the file size on disk and how large the scan can reprint.
Scan output calculator
Reading the numbers
Pixel dimensions are the print's inches multiplied by the scanning DPI, and everything else follows from them. Megapixels tell you how the scan compares with a camera. The TIFF figure is the true uncompressed weight of the data, three bytes per pixel; the JPEG figure is a realistic high-quality export at roughly a tenth of that. The reprint ceiling divides the pixels back down by 300 PPI, the standard for a print viewed in the hand.
Common combinations are also written up as quick-reference pages, for example a 4 x 6 at 600 DPI, with the full table for each. If you are still choosing a DPI, start at the DPI advisor.
Common questions
- How many pixels is a 4 x 6 photo at 300 DPI?
- 1200 x 1800 pixels, which is 2.2 megapixels. At 600 DPI the same print becomes 2400 x 3600 pixels, 8.6 megapixels, and that difference is exactly why archival scans use the higher setting.
- Why is my scanned file so large?
- Uncompressed formats like TIFF store three bytes per pixel, so a 600 DPI scan of an 8 x 10 runs to hundreds of megabytes. That is normal for a master file. Keep the TIFF as the archive and export JPEGs from it for everyday use.
- Should I save scans as JPEG or TIFF?
- Master scans of irreplaceable photos deserve TIFF or PNG, because JPEG throws information away every time it saves. For copies you share or upload, JPEG at high quality is fine and roughly a tenth of the size.
- Does a higher DPI scan take longer?
- Yes, but the difference is seconds per photo on any modern flatbed. Against the decades the file is meant to last, scan time is the wrong thing to optimise.
The file is made. Now make it worth keeping
A master scan faithfully records every tear and fade. Photo Restore repairs them on your iPhone, and the album page comes back to life.
