What is the postage rate to Bermuda?

You can send international First-Class letters and flats up to 4 pounds as large envelopes or packages by attaching extra First-Class Mail® stamps. First-Class Package International Service® and Priority Mail International™ Flat-Rate Envelopes provide convenient flat-rate packaging options for your documents and merchandise (**up to 4 pounds for Priority Mail International Flat-Rate Envelopes or up to 20 pounds (varies by country) for Priority Mail International boxes.