Fill-crop DPI
Paper is oriented to match the image (landscape file → landscape paper) unless you turn that off. The largest rectangle of the paper’s aspect ratio is taken from the image. Fill DPI is cropped width ÷ paper width in inches. Height yields the same DPI when the crop is exact.
Fit DPI uses the whole image letterboxed onto the paper. It is usually slightly higher and leaves margins. Labs almost always fill-crop unless you order a border.
Quality bands (close view)
- Excellent — from 300 DPI. Sharp at arm’s length. The conventional target for albums, portfolios, and small photographic prints.
- Very good — from 240 DPI. Fine for most close-view prints. A slight softness may show only under a loupe or in tight crops.
- Good — from 150 DPI. Widely accepted for posters, canvas, and apparel art viewed from a step back. Many POD vendors treat 150 DPI as a minimum.
- Fair — from 100 DPI. Acceptable for larger wall prints if people stand a couple of feet away. Not ideal for handheld photos.
- Low — from 72 DPI. Similar to a sharp screen. Fine for banners and posters seen from several feet, not for desk prints.
- Poor — below 72 DPI. Individual pixels are likely to show at a normal viewing distance. Use a smaller print, a higher-resolution file, or stand farther back.
These thresholds are industry convention, not a laboratory measurement of your printer. A well-tuned inkjet on baryta paper can look excellent below 300 DPI. A cheap dye-sub kiosk can look busy above it.
Viewing distance
Required PPI ≈ 3438 / distance_in_inches. The constant comes from one arc-minute of visual angle: 1 / tan(1′) ≈ 3438 when distance is in inches. It assumes 20/20 acuity, a high-contrast target, and a still observer. It understates the need for small type and overstates the need for soft photographic gradients.
Default viewing distances on each paper size are planning guesses (a 4×6 is held; a 24×36 is not). Override them on the DPI calculator with the distance you actually expect.
What we do not model
- Lens sharpness, diffraction, noise, or camera shake.
- Color management, ICC profiles, or gamut.
- Printer screening, paper white, or ink limits.
- Software upscaling. Extra pixels are not treated as real detail.
- Vendor-specific templates, bleed, or safe areas beyond the notes on the POD page.
Pixel dimensions are read with the browser’s image decoder. EXIF orientation is honoured whencreateImageBitmap supports imageOrientation: from-image. HEIC depends on the browser. Animated GIFs use the first frame’s size.