Find the right scan resolution
1. Units for the sizes you’ll type
2. The print you’re scanning
3. What you want back
4. How closely will it be viewed?
Scan at 600 DPI
That is the standard scanner setting covering this job (2× enlargement at a 300 dpi target).
- Resulting scan
- 2400 × 3600 px
- Resolution at the reprint size
- 300 dpi — gallery-grade — crisp even inspected up close
- Largest honest size from this scan
- 12 in (30 cm) long edge at 300 dpi
Scan once at this setting and keep the file: it already covers every smaller reprint, and rescanning cannot add detail the print does not hold. Save as TIFF or maximum-quality JPEG and leave the scanner’s auto-sharpen off.
Scan settings for common prints (300 dpi print target)
| Print you are scanning | Same-size copy | Reprint at 8 × 12 in | Reprint at 16 × 24 in | Reprint at 24 × 36 in |
|---|---|---|---|---|
| Wallet print (2.5 × 3.5 in) | 300 dpi | 1200 dpi | 1200 dpi (detail limit — restore to go bigger) | 1200 dpi (detail limit — restore to go bigger) |
| 3.5 × 5 print (3.5 × 5 in) | 300 dpi | 1200 dpi | 1200 dpi (detail limit — restore to go bigger) | 1200 dpi (detail limit — restore to go bigger) |
| 4 × 6 print (4 × 6 in) | 300 dpi | 600 dpi | 600 dpi (detail limit — restore to go bigger) | 600 dpi (detail limit — restore to go bigger) |
| 5 × 7 print (5 × 7 in) | 300 dpi | 600 dpi | 600 dpi (detail limit — restore to go bigger) | 600 dpi (detail limit — restore to go bigger) |
| 8 × 10 print (8 × 10 in) | 300 dpi | 600 dpi | 600 dpi (detail limit — restore to go bigger) | 600 dpi (detail limit — restore to go bigger) |
Everything on this page is computed in your browser from the sizes you type — they are never uploaded, stored or sent, and analytics count views, starts, completions and errors without them.
Scanning a photo you love? Turn it into a painted portrait →What DPI should you scan photos at?
The arithmetic is one multiplication: required scan DPI = print-quality target × enlargement factor. A same-size archive copy of any photo wants 300 dpi — the long-standing archival floor for prints. Doubling the size doubles the requirement: reprinting a 4 × 6 at 8 × 12 needs 300 × 2 = 600 dpi. Scanners expose stepped settings rather than arbitrary numbers, so the calculator rounds your exact need up to the setting every flatbed and scan app offers — 300, 600 or 1200 — and shows the pixel dimensions that setting produces.
There is a physical ceiling the arithmetic alone would hide: a photographic print only holds roughly 600 dpi of real detail, so scanning an ordinary 4 × 6 at 1200 dpi mostly produces a bigger file of sharper paper grain. Small wallet-size lab prints are the honest exception — packed detail in a tiny frame makes a 1200 dpi pass worth it. When your reprint asks for more than the print can give, this calculator says so instead of prescribing a useless setting: scan at the ceiling, then let the free photo restorer rebuild detail, or choose a smaller size from the portrait size guide.
Scan-then-print is the reverse of print-from-pixels
This page starts from a physical print and works out the scanner setting. The canvas size calculator is its mirror image: it starts from a digital photo’s pixels and rates the print sizes those pixels support — use it on the file your scan produces. Whether the picture needs cropping to a print shape belongs to the photo aspect ratio calculator, and repairing fading, tears and creases in the scanned image is the photo restorer’s job, not a scanner setting.
Three habits make any scan noticeably better at every DPI: wipe the scanner glass and the print (dust scans as white specks that look like damage), save as TIFF or maximum-quality JPEG rather than a compressed default, and switch off the scanner’s auto-sharpen — restoration tools work best on an unsharpened original. And if the photo you are digitizing is one that matters — a wedding print, a grandparent’s only portrait — the same scan can become a painted portrait printed at gallery resolution regardless of the original’s size.
How it works
- Pick the print you are scanning — wallet through 8 × 10 — or type its exact size in inches or centimeters.
- Choose what you want back: a same-size archive copy or a larger reprint, and whether it will be inspected up close or seen across a room.
- Read the scanner setting, the pixels it produces and the largest size that scan honestly supports — then scan once and keep the file.
Frequently asked questions
What DPI should I scan old photos at?
600 dpi is the safe answer for family photos: it archives a 4 × 6 with room to reprint at double size, and it is the most real detail an ordinary photographic print can give a scanner. Use 300 dpi if you only ever need same-size copies, and 1200 dpi for small wallet-size prints, which genuinely hold detail worth capturing. This calculator turns those rules into an exact setting for your specific print and reprint size.
Is a higher scan DPI always better?
No. A photographic print holds roughly 600 dpi of real detail; above that a scanner records sharper paper texture and grain, not more picture, while the file size grows with the square of the setting. Scanning a 4 × 6 at 2400 dpi produces a file sixteen times larger than 600 dpi with essentially the same usable image. Spend the effort on a clean 600 dpi scan instead — and on restoration if the print itself is the limit.
What DPI do I need to scan a 4 × 6 photo to print it at 16 × 20?
The exact arithmetic asks for 1200 dpi (a 4× enlargement at a 300 dpi print target), but that exceeds what a 4 × 6 print physically holds. Scan at 600 dpi — the honest ceiling — which yields 2400 × 3600 pixels and about 150 dpi at 16 × 20: sharp at wall-viewing distance, softer inspected up close. For a close-viewing 16 × 20, restore and upscale the 600 dpi scan rather than raising the scanner setting.
Should I scan the print or the original negative?
The negative, if you have it. Film holds far more detail than a print made from it — negatives and slides are worth 2400–4800 dpi on a scanner with a film carrier, and a good film scan enlarges much further than any print scan. This page’s math is for prints, which is what most people actually still have; if a negative exists, scan that instead and treat this calculator’s answer as the fallback.
Is my photo uploaded to calculate this?
No — there is nothing to upload. You type sizes; every calculation runs in your browser from those typed numbers, which are never sent anywhere, stored, or included in analytics. Limited usage analytics count views, starts, completions and errors only. If you later use the photo restorer or a portrait tool, those pages explain their own handling separately.
Scanning a photo you love? Turn it into a painted portrait →