USPS Publication 28 (Postal Addressing Standards) recommends that addresses be written in all capital letters with no punctuation — commas, periods and apostrophes are dropped — because uppercase letters are more distinct for the optical-character-recognition equipment that sorts mail, which improves both machine and manual handling. The one punctuation mark to keep is the hyphen in a ZIP+4 code (and in hyphenated street numbers in New York and Hawaii). The recommended order is: recipient name, then any company / ATTN line, then the delivery (street) line(s), then a single “CITY STATE ZIP” line with one space between city and state and the ZIP last. AnyTool’s Envelope Address Formatter gives you a UPPERCASE toggle and a strip-punctuation toggle (both on by default), preserves the ZIP+4 hyphen, and builds the CITY STATE ZIP line for you. Uppercase is a recommendation, not a strict requirement — for wedding invitations or greeting cards you can turn it off for a mixed-case look.

The US #10 is the standard business envelope at 4.125 × 9.5 inches (about 105 × 241 mm). Other common US sizes are #9 (3.875 × 8.875 in, the reply envelope that fits inside a #10), #6¾ (3.625 × 6.5 in, a small personal / cheque envelope), 6 × 9 in (booklet / catalog), and the A-series invitation envelopes A2 (4.375 × 5.75 in), A6 (4.75 × 6.5 in) and A7 (5.25 × 7.25 in, for 5×7 greeting cards). The ISO C-series, used across Europe and most of the world, runs DL (110 × 220 mm, the standard letter envelope), C6 (114 × 162 mm), C5 (162 × 229 mm, which holds an A4 sheet folded once) and C4 (229 × 324 mm, which holds an unfolded A4). AnyTool builds the PDF page at the exact chosen size in points (inches × 72, or millimetres × 2.8346), so when you print at 100% / “Actual size” the layout matches the real envelope.

For international mail, USPS and the Universal Postal Union say the last line of the address must be the complete destination country name, by itself, in all capital letters, with no abbreviation and nothing else on that line (any foreign postal code goes on the line above, with the city). Sorting machines in the USA and many countries read and route by that country name, so it has to be clear and standardized. In AnyTool’s Envelope Address Formatter you simply fill in the Country field on the delivery address; if it is left blank the mail is treated as domestic and no country line is printed, and if you enter a country it is automatically uppercased and placed on the last line of the delivery block. Note the tool does not translate or verify the country name, so spell it in English (or the destination country’s accepted form) and double-check it.

All formatting and PDF generation happen locally on your device with a vector engine — there is no upload, no server, no CDN and no tracking, so the sender and recipient details you enter never leave the browser, and the page works offline once cached. That is a real privacy win over cloud envelope-printing services that store your addresses on a server. Be clear about the limits, though: the tool formats and prints addresses on standard envelope sizes, but it does NOT validate or verify addresses against a postal database (check the spelling, street, city, state and ZIP yourself), does NOT add a real USPS Intelligent Mail barcode (IMb) or any scannable postal barcode, and does NOT buy postage. Printers also feed envelopes very differently — face-up vs face-down, top-first vs bottom-first — so test-print on a sheet of plain paper, check the orientation against a real envelope, and print the PDF at 100% / “Actual size” (never “Fit to page”).