For a standard letter to Canada weighing up to 1 ounce, one Global Forever stamp is all you need. That single stamp is worth $1.70 in 2026 and covers the international letter rate exactly. If your letter is heavier, square, or stuffed with anything bulky, you’ll need more postage, and the number of stamps depends on what you’re using to make up the total.
Stamps by Weight
Canada sits in USPS Price Group 1, the cheapest international tier. As of January 18, 2026, the First-Class Mail International rates for letters to Canada are $1.70 up to 1 ounce, $2.00 up to 2 ounces, $2.70 up to 3 ounces, and $3.40 up to 3.5 ounces.1Postal Explorer. Notice 123 – USPS Price List Effective January 18, 2026
A domestic Forever stamp is worth $0.78 in 2026,2USPS.com. Stamps and a Global Forever stamp is worth $1.70 and always covers the 1-ounce international rate even after future price hikes.1Postal Explorer. Notice 123 – USPS Price List Effective January 18, 2026 Working from those two values, here’s what covers each weight tier:
- 1 ounce ($1.70): one Global Forever stamp. Domestic stamps alone take three ($2.34), overpaying by $0.64.
- 2 ounces ($2.00): one Global Forever plus one domestic ($2.48), or three domestic stamps ($2.34).
- 3 ounces ($2.70): one Global Forever plus two domestic ($3.26), or four domestic stamps ($3.12).
- 3.5 ounces ($3.40): two Global Forever stamps hit $3.40 exactly. Five domestic stamps ($3.90) also work but overpay.
USPS doesn’t refund overpaid postage, so combining stamps is a convenience-versus-cost tradeoff. If you want to pay the exact rate, buy postage at the counter or through usps.com.
Square Cards and Bulky Envelopes Cost Extra
Even a 1-ounce envelope can trigger a $0.49 nonmachinable surcharge on top of the regular rate. Your letter is nonmachinable if it has clasps, strings, or button closures; contains loose items like keys, pens, or coins that make the thickness uneven; is square rather than rectangular; or is too rigid to bend around the sorting equipment.3Postal Explorer. Notice 123 – USPS Price List Effective January 18, 20264About USPS. Publication 25 – Section: 3-6 Nonmachinable Criteria
Square greeting cards are the most common trap. A 1-ounce square card to Canada costs $2.19 instead of $1.70, so a Global Forever stamp alone won’t cover it. Add a domestic stamp and you’re set.
When Your Envelope Is Too Big for Letter Rates
Letter pricing has size limits. Your envelope has to measure at least 5½ by 3½ inches and no more than 11½ by 6⅛ inches, with a thickness between 0.007 inch and ¼ inch.5Postal Explorer. First-Class Mail International 240 – Section: 241.2 Description and Physical Characteristics Anything larger, or anything over 3.5 ounces, gets reclassified as a large envelope (flat), and the price jumps to $8.55 for weights up to about 16 ounces.1Postal Explorer. Notice 123 – USPS Price List Effective January 18, 2026 If your envelope is close to the letter limits, it’s cheaper to slim the contents than to pay the flat rate. For actual flats, buy exact postage at the counter rather than layering stamps.
Address It So It Gets There
Canadian addresses look a little different from U.S. ones. The city, province abbreviation, and postal code all sit on the same line, with two spaces between the province and the postal code. Canadian postal codes alternate letters and numbers in a pattern like K1A 0B1, with one space in the middle and no hyphen.6Canada Post. Addressing Mail Accurately Write “CANADA” in capital letters on the last line.
A correctly formatted envelope reads:
JANE SMITH
123 MAPLE AVE APT 4
TORONTO ON K1A 0B1
CANADA
Use the two-letter province abbreviation instead of spelling it out. Common ones are ON (Ontario), QC (Quebec), BC (British Columbia), and AB (Alberta).7Canada Post. Symbols and Abbreviations Put your return address in the upper left corner with “USA” on its last line.8USPS. How to Send a Letter or Postcard
Personal letters and documents don’t need a customs form when sent to Canada by First-Class Mail International.9Postal Explorer – USPS. Country Conditions for Mailing – Canada If you’re slipping anything other than paper into the envelope, check Canada’s restricted-items list first, because things like lighters with fuel, certain metals, and items that simulate munitions can’t be mailed in.
Dropping It Off and How Long It Takes
A standard letter with proper postage can go in any blue USPS collection box. For square cards, oversized letters, or anything that needed more than a single Global Forever stamp, take it to the post office counter so a clerk can weigh it and confirm the rate before it enters the mail stream.
USPS doesn’t guarantee a delivery date for First-Class Mail International to Canada.10USPS. International Mail Services and Shipping Rates Most letters arrive within one to three weeks, and customs processing can add time. There’s no tracking on First-Class Mail International letters, so if you need delivery confirmation, Registered Mail is an add-on service for $23.40 on top of postage.11About USPS. Postal Bulletin 22680 – Price Changes for International Mailing Services