Within Canada (Lettermail™)

CATEGORY		SIZE (length x width x thickness)	ASPECT RATIO *	WEIGHT
Standard Lettermail
Cards and postcards	MIN	140 x 90 x 0.18 mm (5.6 x 3.6 x 0.007 in)	1.3 : 1	Should weigh enough to provide the stiffness needed to withstand processing without difficulty.
Cards and postcards	MAX	235 x 120 x 5 mm (9.2 x 4.7 x 0.2 in)	2.6 : 1
Other (e.g. envelopes and self-mailers)	MIN	140 x 90 x 0.18 mm (5.6 x 3.6 x 0.007 in)	1.3 : 1	3 g (0.11 oz)
Other (e.g. envelopes and self-mailers)	MAX	245 x 156 x 5 mm (9.6 x 6.1 x 0.2 in)	2.6 : 1	50 g (1.75 oz)
Medium Lettermail
	MIN	140 x 90 x 0.18 mm (5.6 x 3.6 x 0.007 in)	1.4:1
	MAX	235 x 165 x 5 mm (9.2 x 6.5 x 0.2 in)	1.4:1	up to 50 g (1.75 oz)
Other Lettermail (e.g. envelopes, cards and self-mailers)
Non-standard***	MIN	140 x 90 x 0.18 mm (5.6 x 3.6 x 0.007 in)	N/A	3 g (0.11 oz)
Non-standard***	MAX	380 x 270 x 20 mm (14.9 x 10.6 x 0.8 in)	N/A	500 g (17.6 oz)
Oversize	MIN	140 x 90 x 0.18 mm (5.6 x 3.6 x 0.007 in)	N/A	5 g (0.18 oz)
Oversize	MAX	380 x 270 x 20 mm (14.9 x 10.6 x 0.8 in)	N/A	500 g (17.6 oz)
* Aspect ratio is the relationship between length and width. Standard and Medium Lettermail must be rectangular. ** Some items, like coins, pens, seeds, powders, cannot be mailed as Standard Lettermail, but they can be mailed as Non-standard or Oversize Lettermail. For a link to the full list of unacceptable items, see Resources on the left. *** Non-standard Lettermail is mail that may meet the size requirements for Standard Lettermail but is not rectangular and/or contains items that cannot be mailed as Standard Lettermail (e.g. coins, seeds, powders).