In USA, Canada and parts of Mexico you can find the following paper sizes. The 4 most commonly used US standard paper sizes are known as Letter, Legal, Ledger and Tabloid.
Letter Size
Legal Size
Tabloid Size
Ledger Size
Canadian paper sizes
In Canada they also use P series.
P1
560 x 860 mm
22.0 x 33.9 in
P2
430 x 560 mm – 16.9 x 22.0 in
P3
280 x 430 mm – 11.0 x 16.9 in
P4
215 x 280 mm – 8.5 x 11.0 in
P5
140 x 210 mm – 5.5 x 8.3 in
P6
105 x 140 mm – 4.1 x 5.5 in
International standard for papers
Most countries don’t use US standard paper sizes. The A-series is the International Standard for paper sizes (ISO).