We use USPS (United States Postal Service) actual weight service. Which calculates actual shipping and tax rates based on the total weight of the products you are purchasing and it's destination from our shipping location.

Shipping in United States
First Class Package (total weight below 1 pound)
Priority Mail (total weight above 1 pound)

Shipping in Canada
First-Class Mail International (total weight up to 4 lbs (64 oz)
Priority Mail International  (total weight above 4 pounds)