Sources
The references behind our definitions, conversions and disclosure approach.
Source links are editorial references, not affiliate links. A manufacturer’s sizing convention applies to its own products unless stated otherwise.
Adobe — standard photo sizes
Examples of nominal photo and poster sizes. All ratios and pixel tables on this site are independently calculated.
Adobe — image resizing basics
Relationship between pixel dimensions, physical print size and pixels per inch.
NIST — SI units: length
Exact conversion: 1 inch = 25.4 millimeters.
Canon Australia — paper sizes
Manufacturer table of ISO A-series paper dimensions.
Frame It Easy — measuring a picture frame
Inside sizing, outside dimensions and the distinction between mat opening and outer board.
Frame It Easy — help center
A manufacturer-specific ¼ inch overlap per side. This is an example, not a universal allowance.
Cheeky Sheep — mat sizing guide
Examples of openings ¼–½ inch smaller overall than the artwork; back-opening frame measurements.
FTC — endorsement disclosure guidance
Basis for clear nearby disclosure of future affiliate relationships.
Cloudflare — Web Analytics
Privacy-first audience and performance measurement without cookies.
Original calculations
Conversion tables, mat examples, area comparisons, pixel calculations and layout diagrams are calculated by Frame Size Lab. No product price, rating, availability or preservation claim is inferred from a size entry.