The USPS Priority Mail International Flat Rate Envelope costs $32.65 to Canada and $48.80 to Mexico. The price tops out at $62.35 for group 7. The envelope holds up to 4 lb, and the price does not change with the weight.
It suits documents, small garments and other flat items going abroad. Prices below come from USPS Notice 123 (July 12, 2026) and are retail rates.
Price of the USPS Priority Mail International Flat Rate Envelope by Group
USPS sorts every destination country into a price group. Notice 123 lists this envelope for groups 1 through 8. Group 1 is Canada and group 2 is Mexico.
The postage price calculator shows the group for other countries.
| Price group | Retail price |
|---|---|
| 1 (Canada) | $32.65 |
| 2 (Mexico) | $48.80 |
| 3 | $49.75 |
| 4 | $54.55 |
| 5 | $52.30 |
| 6 | $53.00 |
| 7 | $62.35 |
| 8 | $50.55 |
Commercial rates are slightly lower. A walk in sender pays the retail figure. The notice does not list group 9 for this envelope, so use the calculator for those countries.
Price does not rise in a straight line with distance. Group 5 at $52.30 costs less than group 4 at $54.55, and group 8 at $50.55 costs less than group 7 at $62.35. Always look up the exact country before you budget.
Size and Weight Limits
The standard envelope measures 12-1/2 by 9-1/2 inches. The Legal Flat Rate Envelope is 15 by 9-1/2 inches. Internationally both share one price, so pick the legal size when your documents need the length.
Both are capped at 4 lb. Some countries set lower weight limits. A heavy envelope can be refused even when it is under the USPS cap.
The container must be a USPS envelope. Flaps must close within the normal folds. Tape may reinforce the seams, but you may not enlarge or rebuild the envelope.
Delivery Time and Tracking
USPS lists 6 to 10 business days for many major markets. Customs processing can stretch that. USPS says the timeframe varies with origin and destination.
Tracking is the catch. USPS says Priority Mail International includes tracking, with limits for some destinations. It also states that tracking is not available on Flat Rate Envelopes or the Small Flat Rate Box.
If you need a trackable shipment, read the guide to Priority Mail International and look at the weight based parcel option.
Insurance Included With the Envelope
Coverage is built in. USPS includes up to $100 for nonnegotiable documents and up to $200 for merchandise. The maximum can be lower for some countries.
Notice 123 prices extra merchandise insurance once the value passes $200. Above $900 you add $3.70 per $100 or fraction.
| Declared value | Insurance fee |
|---|---|
| Up to $200 | $0 (included) |
| $200.01 to $300 | $13.85 |
| $300.01 to $400 | $17.55 |
| $400.01 to $500 | $21.25 |
| $500.01 to $600 | $24.90 |
| $600.01 to $700 | $28.55 |
| $700.01 to $800 | $32.30 |
| $800.01 to $900 | $35.95 |
The maximum is $5,000, and it also depends on the country. Domestic Priority Mail has its own separate $100 coverage, so do not mix the two.
Customs Forms You Need
Every international package needs computer generated customs paperwork. USPS offers three routes. Print it through Click-N-Ship, create it online before your visit, or fill out PS Form 2976-R at the post office.
Describe the contents and value accurately. The form also helps decide what duties the receiver may owe. Use the international duty estimator for a rough figure.
The Customs Delivered Duty Paid fee for Priority Mail International is $0.00 per piece. The receiver can still owe duties under the destination country’s rules.
Priority Mail Express International Envelope Prices
The Express version of the envelope uses the same 4 lb cap and the same groups. Notice 123 lists it at $62.70, $83.35, $79.80, $85.20, $87.10, $89.20, $102.50 and $80.85 for groups 1 through 8. That is roughly $30 to $40 more than the standard envelope in each group.
For rules and service details, see the official USPS Priority Mail International page.
Flat Rate Envelope vs Other International Options
The envelope wins for flat items under 4 lb going to a costly group. It loses on tracking. Compare the containers before you pay.
| Option | Weight cap | Group 1 (Canada) | Group 2 (Mexico) |
|---|---|---|---|
| Flat Rate Envelope or Legal Flat Rate Envelope | 4 lb | $32.65 | $48.80 |
| Small Flat Rate Box | 4 lb | $33.75 | $50.45 |
| Medium Flat Rate Box | 20 lb | $61.80 | $90.85 |
| Large Flat Rate Box | 20 lb | $75.15 | $102.55 |
| Priority Mail Express International Flat Rate Envelope | 4 lb | $62.70 | $83.35 |
The Express envelope costs about double to Canada. It adds faster service, covered in the Priority Mail Express International guide.
The domestic padded version works differently, as the padded flat rate envelope article explains.
Is a Letter Cheaper Than the Flat Rate Envelope?
For a plain letter, yes, by a wide margin. First-Class Mail International charges $1.75 for a 1 oz letter to every group. A 3.5 oz letter costs $3.50 to Canada, $4.15 to Mexico and $5.75 to groups 3 to 9.
Letters stop at 3.5 oz, so thicker items need a package service. The cheaper one is First-Class Package International Service, which USPS prices from $19.40 at retail for packages up to 4 lb and worth up to $400, with delivery that varies by destination.
That makes it the usual choice for a light parcel to Canada, where the flat rate envelope’s $32.65 only pays off once the contents weigh enough to push the by weight price higher. Both services need the same computer generated customs form, and First-Class Package gets electronic delivery confirmation only to select destinations when you ship online.
How to Send One Step by Step
- Confirm the destination country’s price group and its weight limit.
- Pack under 4 lb and close the flap within its normal folds.
- Create the customs form through Click-N-Ship, online, or with PS Form 2976-R.
- Check your flat rate box selector result if the contents might not fit an envelope.
- Pay the group price and keep your receipt, since tracking is not offered on this envelope.
When the Flat Rate Envelope Makes Sense
Use the Priority Mail International flat rate envelope for dense, flat items between letter size and 4 lb. Good fits are paperwork stacks, clothing, books and small flat goods. Skip it when you need tracking or when the item is light enough for letter postage.
Check the destination country’s limits before you pack the USPS priority mail international flat rate envelope, since some countries cap weight below 4 lb. Buyers who ship often can also compare the envelope against the box shapes. Then confirm your customs form matches the contents.
Bottom Line on the International Flat Rate Envelope
The USPS priority mail international flat rate envelope is a fixed price shipping option that rewards dense, flat items under 4 lb. It carries included coverage and a 6 to 10 business day target, but no tracking. Match it to your destination group before you buy.
