Sending a Letter From the UK to the USA

To send a letter from the UK to the USA, prepare an addressed envelope and buy Royal Mail postage for its contents, size and weight. Compare International Standard for everyday correspondence with International Tracked & Signed when you need tracking and a delivery signature. If the recipient accepts a printed copy, US printing is another option—but Postmarkr requires a usable US return address.

Buying Royal Mail postage online still means preparing and posting your envelope in the UK. Uploading a PDF for US printing creates a new paper letter in the US. That distinction matters more than whether both websites have a “send” button.

An envelope with two sheets: size, cost and delivery#

For this example, fold two sheets of paper into a 220 × 110 mm envelope, with no other enclosures. Weigh it after sealing: this price applies to a letter weighing no more than 100 g.

• Size: That envelope fits Royal Mail’s Letter format. The sealed item must be no larger than 240 × 165 mm and no thicker than 5 mm.
• Postage: £3.60 for International Standard to the USA, bought online or at a Post Office. This is postage only; supply your own paper and envelope.
• Delivery: Royal Mail’s USA delivery aim is 6–7 working days. It is an estimate, not a guaranteed arrival date.

A larger or thicker envelope needs a different format and price. If you need tracking or a delivery signature, compare the recorded service below before buying postage.

Sources: Royal Mail prices and size limits (opens in new tab); USA delivery guidance (opens in new tab). Checked October 25, 2026.

A typed letter has a second route when a printed copy will do: send it as a US letter online. Postmarkr prints your PDF in the US and mails it USPS First-Class, $2.05 all-in for one black-and-white page, charged in US dollars. You need a US return address you’re allowed to use.

Start with what must be inside the envelope#

An original handwritten note, an ink-signed page or a physical enclosure needs a route that carries the object you have. A scan can reproduce its appearance, but the recipient receives a printed copy. Ask the recipient whether that is acceptable before replacing the original with an upload.

For an ordinary typed letter, the choice may be more practical. Can you print and prepare the envelope locally? Do you have a usable US return address if the online service requires one? What mailing record does the recipient ask for? Write down those answers before comparing prices.

Our guide to sending a letter to the USA from abroad explains the broader choice. This guide focuses on making that choice from the UK, including Royal Mail’s destination guidance and the questions to settle before you buy postage.

Use Royal Mail’s USA page for the finished envelope#

Measure and weigh the sealed envelope, including every enclosure. On Royal Mail’s USA country guide (opens in new tab), check whether it fits Letter or Large Letter before comparing prices. An unfolded A4 page needs a larger envelope than folded correspondence; do not price it from the page count alone.

Start with International Standard (opens in new tab) or International Tracked & Signed (opens in new tab). The choice depends on what record you need:

For a live quote, open Royal Mail’s postage tool (opens in new tab) with the USA destination, actual contents, sealed weight, envelope dimensions and required service ready. Check the offered delivery aim alongside the price. If using a Post Office, take the prepared envelope and ask staff to confirm its format and service before paying.

Buy postage online and follow the offered collection or drop-off instructions, or buy it at a Post Office. Keep the receipt and any tracking reference. Check Royal Mail’s international service updates (opens in new tab) before sending time-sensitive mail; a delivery aim is not a guaranteed arrival date.

Add the USA country line to the delivery address#

For a letter physically posted from the UK, Royal Mail says to put the country name on the last line in capitals and permits “USA.” Keep the recipient’s US city, state and ZIP together above that country line.

Write the address as separate lines, without labels such as “Street” or “Country.” This is a fictional layout, not a verified delivery address:

MORGAN LEE
123 EXAMPLE STREET
BOSTON MA 02110
USA

Use the recipient’s real supplied address. Do not copy an example ZIP into your envelope. Ask for the complete mailing address if the message you received contains only a company name or a street without its city and ZIP.

The envelope-addressing guide covers ordinary placement and domestic address details. The added country line is the part that tells a UK-origin letter where it is going internationally.

Separate correspondence from goods when checking customs#

Royal Mail’s shop help guidance (opens in new tab) distinguishes letters, greetings cards and personal correspondence in eligible letter formats from goods, gifts and items of value. Its guidance says the former do not require customs data; the latter have customs requirements.

Do not assume that everything fitting inside an envelope counts as correspondence. A note and a small gift are a different contents description from a note alone. Explain the actual contents when buying postage and follow the current service instructions. If the documents are unusual or the classification is unclear, ask Royal Mail before sealing and posting them.

This matters when comparing online printing too. A print-and-mail service reproduces the uploaded pages. It cannot take a gift, certificate or other physical object from your desk and put that original into the US envelope.

Check the US return address before choosing online printing#

Postmarkr can print an uploaded PDF and arrange US letter mailing, but a usable US return address is required. If you do not have an address you are authorized to use, resolve that requirement first or choose a physical mailing route from the UK.

If a trusted contact agrees to handle returned mail, confirm both permission and what happens if a letter comes back. Do not enter a random address or assume that using somebody’s address makes them responsible for your correspondence. Your UK contact details can remain in the letter where the recipient needs them; that does not replace the service’s US return-address requirement.

Have the recipient’s US address and a final PDF ready. Postmarkr prints on US Letter paper and adds a separate address page. For an eligible A4 PDF, use the fit-to-US-Letter option if offered, then inspect every page in the preview. If fitting is unavailable, export a US Letter PDF and upload that instead. Review the proof and checkout total for your actual document and options, and confirm that your payment method is accepted.

Postmarkr does not currently offer Certified Mail. It cannot provide an original ink signature or insert a physical enclosure through a PDF upload. If the recipient requires either, use a route that can meet the requirement.

Compare complete costs and separate preparation from transit#

For the UK route, add printing and the envelope to your Royal Mail quote, including any required extras. For US printing, use the checkout total plus any currency conversion or payment fees charged by your payment provider. Compare the same document and required mailing record: a quote for an ordinary letter does not answer a request for tracking and a signature.

Timing also has stages. A prepared UK envelope must reach the chosen collection or acceptance point. An online order must be processed and printed before postal handoff. Payment confirmation does not establish that the letter has entered the mail, and a delivery estimate is not a guarantee.

Before sending, confirm that the recipient will receive the original or copy they asked for, at their complete mailing address. Save the final document and postage or order receipt. For Royal Mail, complete the booked handoff; for US printing, follow the order status through mailing rather than treating payment confirmation as dispatch.