Through Royal Mail, an ordinary letter up to 100g costs £3.60 with International Standard, and Royal Mail aims to deliver it to the USA in 6 to 7 working days. You can send your letter from the UK through Royal Mail, or send a digital file to a service that prints and mails it inside the US. Choose Royal Mail or another suitable physical carrier when the actual paper needs to travel. Consider US printing when the recipient accepts a printed copy and you can meet the service’s address and payment requirements.
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.
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#
Start with Royal Mail’s current USA country guide (opens in new tab). It lists services and separates letter, large-letter and parcel formats. Measure and weigh the sealed envelope rather than estimating from the document’s page count. Heavy paper, a thicker envelope or an enclosure can change the format you need.
Then look up the service for the thing you are sending. Royal Mail’s International Standard page (opens in new tab) describes an everyday international option; its destination-specific information should guide your purchase. If you need a mailing record, tracking or a signature, compare those features explicitly rather than assuming they accompany all international postage.
Royal Mail’s USA country guide (opens in new tab), checked October 2026, puts an ordinary letter up to 100g at £3.60 with International Standard, whether you use stamps from a Post Office or buy postage online, and gives a delivery aim of 6 to 7 working days. Royal Mail’s international price chart (opens in new tab) says a UK 1st Class stamp is not enough for any overseas destination, and it asks for an AIR MAIL sticker on International Standard items, or “BY AIR MAIL — PAR AVION” written in the top left corner. If you are sending documents and need tracking with a signature on delivery, International Tracked & Signed costs £8.60 for a letter, with a delivery aim of 5 to 7 working days. Royal Mail takes the signature but doesn’t give you a copy of it or show it online. An unfolded A4 sheet in a large envelope counts as a large letter and costs more.
A useful counter request is: “This envelope contains correspondence only and is going to this US address. Can you confirm its format, the available services and what record each gives me?” If it includes something else, describe that too. Let the classification follow the contents.
Check the current destination notice before paying. Postal services and requirements can change, and a saved price or an old screenshot may describe a service that no longer fits your envelope. Check the current quote and delivery guidance for your service and destination before committing.
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.
Here is a fictional example for formatting only. These lines are not a verified mailing address:
Recipient: MORGAN LEE
Street: 123 EXAMPLE STREET
City, state and ZIP: BOSTON MA 02110
Country: 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. If your PDF is A4, the upload step offers to fit each page onto US Letter without cropping and shows you a preview before you use the fitted file. If a file can’t be fitted safely, for example because it has form fields, a digital signature or clickable links, export it as US Letter and upload it again. 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 postal route, include printing, an envelope, the applicable international postage and any required extras. For US printing, use the actual checkout total; consider any currency conversion or payment charges applicable to your payment method. Those are different baskets of costs. Without matching quotes for your envelope and file, there is no defensible universal “cheapest” winner.
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 committing, keep the final document and recipient instructions together. Confirm the contents, destination, return arrangement, full price and record you will receive. Choose the route that can carry the document the recipient actually needs, then complete that route’s preparation and handoff steps.