How big can you actually print your photo?
PrintDPI answers it with arithmetic, not folklore: a pixels-to-PPI calculator, print-size charts in inches and centimetres, and quality guidance transcribed from what real photo labs publish — with the sources named.
The quick answer
A 12 MP photo (about 4000 × 3000 px) prints sharp to roughly 10 × 13 in at 300 PPI, good to 15 × 20 in at 200 PPI, and still works as a large wall piece viewed from across the room. Run your own numbers →
Start here
The pillars: every size, every verdict band, all sourced.
DPI calculator: pixels + print size → PPI
Effective resolution on both axes, an attributed quality verdict, crop warnings, and reverse mode for megapixels needed.
ChartStandard photo print sizes (in, cm, megapixels)
4×6 to 24×36 with exact cm equivalents and pixel needs at lab minimum, optimal and 300 PPI.
ChartThe DPI quality ladder: 100 to 300+ PPI
What each band looks like in print, which lab publishes which number, and where the lines blur.
All guides
Honest explainers — every factual claim traced to a lab, platform or standards page. Last verified: 2026-11-16.
What DPI actually means (PPI vs DPI, honestly)
Pixels per inch vs dots per inch, why labs blur them, and which one you can control.
HistoryWhere the 300 PPI standard comes from
Traced honestly to halftone screens: 2 × 150 lines per inch in offset printing.
ChartsHow many megapixels for common print sizes
12, 24 and 45 MP mapped against every standard size at 300 / 250 / 200 / 150 PPI.
ScienceViewing distance & DPI: why billboards run at ~20 DPI
Distance bands from large-format industry guidance, from arm's length to 50 feet.
LabsLab print specs explained (real lab pages cited)
mPix's 250/100 chart, Nations' 125/180/300 columns, WHCC's 300 ppi — side by side.
SocialInstagram & social image sizes from official help pages
What Instagram, Meta, LinkedIn and X publish about their own pixel limits.
BasicsScreen resolution vs print resolution
Why a photo that fills a 4K display can still print badly, and vice versa.
EditingResizing vs resampling: honest limits of upscaling
No magic: what resampling can and cannot add, in the labs' own words.
MathAspect ratios & cropping math (3:2, 4:3, 16:9 → prints)
Crop-loss percentages for every common sensor ratio against standard sizes.
PracticalPhoto paper finishes: a practical guide
Glossy, matte, lustre, metallic — what each does to sharpness, glare and fingerprints.
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Charts and numbers, concepts and honesty, practical buying decisions.