About OMCALCULATOR

OMCALCULATOR is a free online reference for paper sizes, unit conversions, and printing dimensions. Every size listed on this site is verified against official international standards including ISO 216, ISO 269, ANSI/ASME Y14.1, JIS, DIN, and others.

What We Cover

ISO A, B, and C series (A4, A3, C4 envelopes, etc.)
US ANSI and Architectural sizes (Letter, Legal, Tabloid, Arch A–E)
US and International envelopes (#10, DL, C5, etc.)
Photography print sizes (2R through 11R)
Raw print stock (RA, SRA)
Japanese, Chinese, Canadian, Swedish, French, and British traditional formats
Book, newspaper, billboard, and business card sizes

Unit Conversions

Every paper size is listed with dimensions in:

Millimeters (mm)
Centimeters (cm)
Meters (m)
Inches (in)
Points (pt) and Picas (pc)
Pixels at 72, 96, 150, 300, and 600 DPI

Free Tools

We provide two free interactive tools:

Paper Size Converter — convert any dimension between all common units
Size Comparison Tool — compare any two paper sizes visually

Our Commitment

All dimensions come from official standards and are cross-verified against multiple industry references. If you spot any inaccuracy, please contact us — accuracy is our top priority.

Privacy

We do not collect personal information. All conversions happen in your browser. See our Privacy Policy for full details.