Royal mail envelope size chart

Here is a Royal Mail envelope size chart for standard envelopes:

A4 Envelopes

• C5 (229 x 162mm / 9 x 6.4 inches)
• C4 (324 x 229mm / 12.8 x 9 inches)
• C3 (324 x 458mm / 12.8 x 18 inches)

DL Envelopes

• DL (110 x 220mm / 4.3 x 8.7 inches)
• DL2 (110 x 250mm / 4.3 x 9.8 inches)
• DL3 (110 x 280mm / 4.3 x 11 inches)

Square Envelopes

• Square C5 (229 x 229mm / 9 x 9 inches)
• Square C4 (324 x 324mm / 12.8 x 12.8 inches)

Large Envelopes

• B4 (364 x 257mm / 14.3 x 10.1 inches)
• B5 (364 x 364mm / 14.3 x 14.3 inches)
• B6 (364 x 457mm / 14.3 x 18 inches)

Specialty Envelopes

• Window Envelopes (various sizes)
• Security Envelopes (various sizes)
• Jiffy Bags (various sizes)

Please note that these sizes are subject to change, and it's always best to check with Royal Mail for the most up-to-date information. Additionally, some sizes may have specific requirements for weight, thickness, or content.