Size and weight requirements

Each Letter-post item must meet the size and weight specifications shown below.

Standard Letter-post envelopes and self-mailers

Metric
Imperial
Requirement Minimum Maximum
Length
140 mm
5.5 inches
245 mm
9.6 inches
Width
90 mm
3.6 inches
156 mm
6.1 inches
Thickness
0.18 mm
0.007 inches
5 mm
0.2 inches
Aspect ratio
1.3 to 1 (U.S.) or 1.4 to 1 (International)
1.3 to 1 (U.S.) or 1.4 to 1 (International)
2.6 to 1
2.6 to 1
Weight
Not applicable
Not applicable
50 g
1.76 ounces

Standard Letter-post cards and postcards

Metric
Imperial
Requirement Minimum Maximum
Length
140 mm
5.5 inches
235 mm
9.2 inches
Width
90 mm
3.6 inches
120 mm
4.7 inches
Thickness
0.18 mm
0.007 inches
Not applicable
Not applicable
Aspect ratio
1.3 to 1
1.3 to 1
2.6 to 1
2.6 to 1
Weight
Not applicable
Not applicable
50 g
1.76 ounces

Other Letter-post items

Metric
Imperial
Requirement Minimum Maximum
Length
140 mm
5.5 inches
380 mm
15 inches
Width
90 mm
3.6 inches
270 mm
10.6 inches
Thickness
0.18 mm
0.007 inches
20 mm
0.79 inches
Aspect ratio
Not applicable
Not applicable
Not applicable
Not applicable
Weight
Not applicable
Not applicable
500 g
17.6 ounces

Please note:

We charge the Standard Letter-post price on items paid by postage stamps that don’t meet the ratio but fall within maximum standard sizes.