International Flat Rate Shipping: USPS Prices & When to Use It

Priority Mail International Flat Rate boxes come in specific sizes:

• Small Flat Rate Box ($30.20) - 8-5/8" x 5-3/8" x 1-5/8" (inner dimensions). Good for documents, small gifts, jewelry, small electronics. Max 70 lbs but realistically fits items up to ~5 lbs.
• Medium Flat Rate Box ($61.50) - Two options: Top-load (11" x 8-1/2" x 5-1/2") or Side-load (13-5/8" x 11-7/8" x 3-3/8"). Good for books, clothing, medium items. Fits ~10-20 lbs of dense items.
• Large Flat Rate Box ($101.95) - Two options: Regular (12" x 12" x 5-1/2") or Board Game style (23-11/16" x 11-3/4" x 3"). Ideal for heavy items where weight-based shipping is expensive.
• Flat Rate Envelope ($30.20) - 12-1/2" x 9-1/2" for documents and flat items.
• Padded Flat Rate Envelope ($30.20) - 12-1/2" x 9-1/2" with padding for fragile flat items.

Flat Rate is most cost-effective in these scenarios:

• Heavy, dense items - Books, tools, metal objects. A 15 lb item in a Large Flat Rate ($101.95) costs less than per-pound Priority Mail International rates to most distant countries.
• Distant destinations - The farther the destination, the more Flat Rate saves. Australia, Japan, and distant countries see biggest savings vs weight-based pricing.
• Items that fit perfectly - A item that exactly fills a Small Flat Rate Box ($30.20) may cost $45+ if shipped in a custom box.
• When you want predictable pricing - E-commerce sellers can quote exact international rates without calculating destination zones.

Flat Rate is NOT best for: lightweight items (use First-Class International), items to nearby countries (Canada/Mexico may be cheaper by weight), or items that don't fit Flat Rate dimensions.

Important rules for International Flat Rate boxes:

• Free boxes from USPS - Order free Flat Rate boxes at usps.com/ship or pick up at Post Offices. Do not use domestic-only Flat Rate boxes internationally.
• 70 lb weight limit - Same as all USPS international. Flat Rate = no per-pound charges, but you can't exceed 70 lbs.
• Must fit and close properly - Items must fit inside the box with lid closing normally. Bulging, taping lid down, or modifying boxes is not allowed.
• Country availability - Available to 190+ countries but not all. Some destinations only accept certain services. Check USPS country pages.
• Customs forms required - Same customs documentation as any international shipment. CN22/CN23 requirements based on value.
• Insurance included - Priority Mail International includes $200 insurance for merchandise, $100 for non-negotiable documents.