The cost of mailing a domestic letter is going up by one cent next January, Canada Post announced Tuesday. But increases won't be quite as muted for mail destined for foreign destinations.

Effective Jan. 16, 2006, the domestic letter rate goes from 50 cents to 51 cents. Mailing letters (30 grams or less in weight) and postcards to the U.S. will rise 4 cents to 89 cents. Mail for other foreign destinations will cost another 4 cents to send – up to $1.49.

Federal regulations require six months notice of the basic letter rate. Increases can also be made only once a year and are limited by a price-cap formula to no more than two-thirds of the inflation rate.

Canada Post says its letter rates compare favourably with those charged in other countries for mail to Canada. In a release, it said the cost to mail a 30-gram letter from the U.S. to Canada is $1.11 in Canadian funds, versus 89 cents for Canada's proposed new letter rate to the U.S.

But the favourable comparison actually applies only for letters that weigh between 28.4 grams and 30 grams.

A U.S.-mailed letter to Canada that weighs 1 ounce (28.4 grams) or less costs only 60 cents US (74 cents Canadian at current exchange rates). The rate for U.S. postcards sent to Canada is 50 cents US (62 cents Canadian).