Here is the info:
Outside Canada for 24 Hours or More
If you are outside Canada for 24 hours or more, you may claim a personal exemption of
up to $CAN50 worth of goods
the goods must accompany you
tobacco or alcohol can not be claimed in this exemption
Note: If you bring in goods worth more than CAN$50 in total, you cannot claim this exemption. Instead you have to pay full duties on all the goods you bring in.
Outside Canada for 48 Hours or More
If you are outside Canada for 48 hours or more, you may claim a personal exemption of
up to CAN$400 worth of goods
the goods must accompany you
you can include some tobacco products and alcohol, but only a partial exemption may apply to cigarettes, tobacco products or manufactured tobacco.
Outside Canada for 7 Days or More
To calculate the number of days you have been outside Canada for the purposes of this personal exemption, do not include the day you left Canada but do include the day you returned.
If you are outside Canada for 7 days or more, you may claim a personal exemption of
up to CAN$750 worth of goods
you can include some tobacco products and alcohol, but only a partial exemption may apply to cigarettes, tobacco products or manufactured tobacco.
alcohol and tobacco products must accompany you
other goods do not need to accompany you when you cross the border.