Envelopes and Covers

Common envelope and cover dimensions

The envelope size system we use today was introduced in the late 1960s. Prior to that envelopes were manufactured in a variety of non-standard sizes.

NB. the second dimension quoted is the flap side

DL 110mm × 220mm – Official First Day Covers since 1970
3½” × 6½” (90mm x 165mm) – Covers 1930s to 1960s
3½” × 6″ (90mm x 165mm) – Covers 1950s
4″ × 9½” (105mm x 240mm) – Some 1960s covers
100mm x 190mm – WWF Covers

International standard sizes

modern envelope sizes
International standard ISO 269 defines several standard envelope sizes, which are designed for use with ISO 216 standard paper sizes:

Format Dimensions (mm) Dimensions (in) Format suitability Bermuda
DL 110 × 220 4¼ × 8⅝ FDCs from 1970 – 1/3 A4  Examples
C7 81 × 114 3.2 × 4.5 A7 (or A6 folded in half)
C7/C6 81 × 162 3.19 × 6.4 1/3 A5
C6 114 × 162 4½ × 6⅜ FDCs from 1973 – A6 (or A4 folded in half twice)  Examples
C6/C5 114 × 229 4.5 × 9 1/3 A4
C5 162 × 229 9 × 6⅜ A5 (or A4 folded in half once)
C4 229 × 324 12¾ × 9 A4
C3 324 × 458 12.8 × 18 A3
B6 125 × 176 4.9 × 6.9 C6
B5 176 × 250 6.9 × 9.8 C5
B4 250 × 353 9.8 × 13.9 C4
E4 280 × 400 11 × 15.75 B4

 

British envelopes

The smallest postal envelopes were 4″ x 2¾”. A good guide is this information from The John Dickinson Lion Brand envelope catalogue for March 1961:

Format Dimensions (mm) Dimensions (in) Format suitability Bermuda
Envelope 79 × 137 3⅛ x 5⅜ n/a
Envelope 83 × 152 3¼ x 6 n/a
Envelope 108 × 137 4¼ x 5⅜ n/a
Envelope 102 × 152 4 x 6 n/a
Envelope 102 × 229 4 x 9 n/a
Window 83 × 152 3¼ x 6 n/a
Window 95 × 159 3¾ x 6¼ n/a
Window 102 × 229 4 x 9 n/a
Business Banker 102 × 229 4 x 9 n/a
Business Banker 204 × 229 8 x 9 n/a
Pocket 229 × 102 9 x 4 n/a
Pocket 381 × 254 15 x 10 n/a

US envelopes

Format Dimensions (mm) Dimensions (in) Format suitability Bermuda
#6¾ 92.1 × 165.1 3⅝ × 6½ n/a  Examples
#7¾ (Monarch) 98.4 × 190.5 3⅞ × 7½ n/a
#9 98.4 × 225.4 3⅞ × 8⅞ n/a
#10 104.8 × 241.3 4⅛ × 9½ n/a  Examples
#11 114.3 × 263.5 4½ × 10⅜ n/a
#12 120.7 × 279.4 4¾ × 11 n/a
#14 127.0 × 292.1 5 × 11½ n/a

Bermuda Stamps

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