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Scan old prints to print size
Scanning a 4 x 6 in print at 600 dpi gives 2,400 x 3,600 pixels, which meets the 100 pixels per inch rule up to 24 x 36 in; at 300 dpi it gives 1,200 x 1,800 and reaches 12 x 18 in. Multiply the scan resolution by the original's inches, then match the result to the list.
Scan sizes against 12 x 18 and 24 x 36 in. Each doubling of the dpi quadruples the pixels.
Scan resolution
Epson's FastFoto FF-680W page lists three output formats: 300 dpi for sharing, 600 dpi (TIFF) for archiving and 1200 dpi for enlarging, with output from 50 to 1200 dpi. The same page gives its optical resolution as 600 dpi and defines the 1200 dpi figure in a footnote as interpolated resolution: the doubling of the optical resolution by a software algorithm. Flatbed models list far higher figures: Epson's Perfection V600 page states 6400 x 9600 dpi alongside film scanning and enlargements (see film and slides).
Largest listed size from each scan
Each cell shows the scan pixels and the largest listed size that meets 100 pixels per inch with a crop allowed. Pixels are original inches x dpi. For the FF-680W the 1200 dpi column is interpolated; a scanner with a higher optical resolution records real detail at that setting.
| Original | 300 dpi | 600 dpi | 1200 dpi (interpolated) |
|---|---|---|---|
| 4 x 6 in print | 1,200 x 1,800: 12 x 18 in | 2,400 x 3,600: 24 x 36 in | 4,800 x 7,200: 48 x 60 in |
| 5 x 7 in print | 1,500 x 2,100: 12 x 18 in | 3,000 x 4,200: 30 x 40 in | 6,000 x 8,400: 48 x 60 in |
| 8 x 10 in print | 2,400 x 3,000: 20 x 30 in | 4,800 x 6,000: 48 x 60 in | 9,600 x 12,000: 48 x 60 in |
| A5 sheet (148 x 210 mm) | 1,748 x 2,480: 16 x 24 in | 3,496 x 4,961: 30 x 40 in | 6,992 x 9,921: 48 x 60 in |
| A4 sheet (210 x 297 mm) | 2,480 x 3,508: 20 x 30 in | 4,961 x 7,016: 48 x 60 in | 9,921 x 14,031: 48 x 60 in |
Worked example
A 4 x 6 in print at 600 dpi: 4 x 600 = 2,400 and 6 x 600 = 3,600 pixels. A 24 x 36 in print needs 2,400 x 3,600, so it fits exactly at 100 ppi. The same print at 1200 dpi gives 4,800 x 7,200, which reaches all 34 sizes, but on the FF-680W those pixels are interpolated from a 600 dpi scan, so see the next section.
Scanning cannot add detail
More dpi adds pixels, not information: past the original's own grain or printed dots the extra pixels copy the same blur. Epson's page puts the optical resolution of this model at 600 dpi, so a 1200 dpi scan from it is software-interpolated, not a finer measurement; the 1200 dpi column shows file size only. Treat the largest size in each cell as the file's size limit, then judge sharpness on the scan at 100 percent.
A4 is 210 x 297 mm, which is 8.27 x 11.69 in; the A-series page shows the paper sizes against the listed frames. Pixel counts here are exact products; the scanner's real output varies with its crop and edge margins.
Sources
- Epson FastFoto FF-680W specifications (manufacturer page), fetched 2026-11-13
- Epson Perfection V600 Photo specifications (manufacturer page), fetched 2026-11-13
Scan resolutions are settings from the manufacturer pages cited; sizes and the 100 ppi rule are from the ArtzFolio Studio table. Page checked 2026-11-13.