USPS-style formatting, no AI required

How to Add an Apartment Number to an Address

Paste a messy address or fill in the fields. The tool formats apartment, suite, PO Box, Attn, and c/o addresses into a clean envelope-ready layout.

Format an address See examples

STAMP

ALEX RIVERA
1855 MAPLE ST
LOS ANGELES CA 90026

TAYLOR ROBINSON
1020 PINE AVE APT 3B
BROOKLYN NY 11211

leave barcode area blank

Instant formatter

Turn address parts into the right envelope format

Use the quick paste box or structured fields. Everything runs locally in the browser with rule-based formatting.

Recipient name Company or organization Street address

Secondary type Number

City State ZIP / postal code

Country for international mail

Address scenario Apartment / unit Business suite PO Box Attn c/o Current resident Family International

Return address

Show return address on envelope Return name Return street

City State ZIP

Formatted output

Ready

Address lines stay in mailing format and are not translated, so delivery details remain accurate.

STAMP

USPS barcode clear zone

Rules baked into the tool

For normal US mail, the clean format is usually street address followed by APT, STE, RM, or FL and the number on the same line.

California becomes CA, Virginia becomes VA, New York becomes NY, and the final city-state-ZIP line is left aligned.

Street, Avenue, Boulevard, Drive, Road, Lane, Place, and directional words become USPS-style abbreviations.

PO Box, Attn, c/o, and business suite addresses use different lines so the mail reaches the right person or department.

Examples

FAQ

Where do I put an apartment number on an envelope?

Put it after the street address on the same line when it fits, such as 1020 PINE AVE APT 3B.

Should I write apartment, apt, unit, or #?

APT is the clearest standard abbreviation for apartment. Use STE for suite, RM for room, and FL for floor.

Do I need a return address?

It is strongly recommended. If the mail cannot be delivered, the return address lets the postal service send it back.

Can I print this on an envelope?

Yes. Use the formatted output for labels, mail merge, or an envelope template. Keep the bottom barcode area blank.