Can you give me measurements for US and UK paper and envelope sizes?

UK and Europe

Standard paper sizes are coded A size – A4 for letterheadings etc, A5 for small brochures and A6 for postcards being the most normal. Each has a corresponding C size for envelopes. Printers use SRA sizes which allow extra space for grip or bleed but printed work should always be specified as the finished, trimmed size.

In the ISO paper size system, the height-to-width ratio of all pages is the square root of two (1.4142 : 1). If you put two such pages next to each other, or cut one into two equal pieces, the resulting page will have again the same width/height ratio.

Non-standard sizes and other considerations

When specifying folders we need to take into account what size the inserts will be – and whether the folder needs to fit into a standard envelope for mailing. For example, a folder might need to be oversized A4 to allow for A4 inserts, but small enough to fit in a standard C4 envelope.

A sizes in mm

A0 = 841 x 1189 mm
A1 = 594 x 841 mm
A2 = 420 x 594 mm
A3 = 297 x 420 mm
A4 = 210 x 297 mm
A5 = 148 x 210 mm
A6 = 105 x 148 mm
A7 = 74 x 105 mm

Common envelope (C) sizes in mm

Designed to fit A size paper – for example, an unfolded sheet of A4 fits a C4 envelope, or folded once it’ll fit into C5.
C3 = 324 x 458
C4 = 229 x 324
C5 = 162 x 229
C6 = 114 x 162

Non C size envelopes

The most common is DL – generally 110 x 220 mm, though oversize DLs are often used for mailings where there is bulky content.

Common US paper sizes

(US measurements are in inches, so mm equivalents are approximate)
Letter: 8.5 x 11 inches (216 x 279 mm)
Legal: 8.5 x 14.0 inches (216 x 356mm)
Tabloid, ledger: 11 x 17 inches (279 x 432 mm)

Common US commercial envelope sizes

# 9: 3 7/8 x 8 7/8 inches
#10: 4 1/8 x 9.5 inches