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Four Line U.S. Address Format Singapore Shippers Need

September 12, 2026
Four Line U.S. Address Format Singapore Shippers Need

A standard US address block generally runs several lines including the recipient's name; an optional company line; the street address with any apartment or suite number; and the city, two-letter state abbreviation, with a ZIP or ZIP+4 code if available. Every line is left-justified. USPS guidelines call for all capital letters and no punctuation on mailpieces, with ZIP+4 recommended over a plain five-digit ZIP whenever available, since it pinpoints delivery down to a specific block or building.

TL;DR:

  • Writing the city, state, and ZIP+4 on the bottom line in all capital letters without punctuation is crucial for automated USPS sorting accuracy.
  • Including the apartment or suite number on the same line as the street address or directly above it prevents misrouting by machine scanners.
  • Using the full city name, two-letter state code, and ZIP+4 significantly improves delivery precision and reduces delays in high-volume mailing.
  • International shipments must add the country name in capital letters at the end of the address and avoid local punctuation or non-Latin characters.
  • Validating ZIP+4 codes through a lookup before printing minimizes scan failures and ensures smoother handling within the USPS automated system.
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Table of Contents

How to Write a US Address Correctly

Getting each line right matters more than most people assume, because USPS Business Mail 101 confirms automated sorting equipment reads addresses from the bottom up. The city, state, and ZIP line is the anchor the machine checks first. Get that line wrong, and everything above it becomes irrelevant to the sorter.

Here's the line-by-line order USPS expects:

  1. Line 1: Recipient name or attention line. Use the full name, or "ATTN: [Name]" if the mail is going to a specific person within a larger organization.
  2. Line 2: Company name (optional). Include this only if you're mailing to a business address.
  3. Line 3: Delivery address. This is the primary street number, any predirectional (N, S, E, W), the street name, the suffix (ST, AVE, BLVD), a postdirectional if one applies, and the secondary designator (APT, STE, UNIT) whenever it fits on the same line.
  4. Line 4: City, state, ZIP. Spell out the city name in full, never abbreviated. Follow it with the two-letter state code and either the five-digit ZIP or the nine-digit ZIP+4.

Keep the apartment or suite number on the same line as the street whenever space allows. If it truly won't fit, USPS says to place it on the line directly above the street, never below. A unit number sitting under the street line is one of the most common reasons machine sorters misroute mail. Cap the whole block at six lines, though four is standard for most residential and business mail.

Examples of Correctly Formatted US Addresses

Seeing the format applied to different situations clears up most confusion faster than reading rules in the abstract.

  • Residential, with predirectional and ZIP+4: JOHN SMITH / 482 N MAPLE AVE / SPRINGFIELD IL 62704-1234
  • Business, with suite and company line: GLOBAL TRADE CO / ATTN ACCOUNTS PAYABLE / 1500 W BROADWAY STE 220 / SAN DIEGO CA 92101
  • Apartment, same-line format (preferred): MARIA LOPEZ / 220 E 14TH ST APT 5B / NEW YORK NY 10003. When space is tight, move "APT 5B" to its own line directly above the street, never below it.
  • PO Box: DAVID CHEN / PO BOX 3345 / AUSTIN TX 78711. Choose a PO Box when the recipient has no reliable street delivery or wants mail held at a postal facility; choose a street address whenever a courier or parcel carrier needs a physical drop-off point, since PO Boxes typically can't accept private carrier deliveries.
  • Military APO/FPO: SGT JAMES WRIGHT / UNIT 2210 BOX 4521 / APO AE 09028. Note the state field carries AA, AE, or AP instead of a standard state code, paired with its own dedicated ZIP+4 range.

USPS Formatting Rules That Affect Machine Readability

Automation is the whole point of these rules. USPS scanners process millions of pieces a day, and every formatting choice either helps or hinders that machine.

Four-line address alignment for scanning

The core rules are consistent across USPS Publication 28 and the Domestic Mail Manual: write addresses in all capital letters, skip commas and periods entirely, and left-justify the whole block. Use standard suffix abbreviations (ST, AVE, BLVD, RD) and the two-letter state codes rather than spelling anything out. Spacing matters too: one space between city and state, two spaces between the state and the ZIP or ZIP+4.

Typography counts as much as wording. UCLA Mail Services recommends a 10 to 14 point font, printed in dark ink against a light background. Avoid reverse type (light text on a dark box) and bright or patterned backgrounds, since both interfere with the optical scanners that qualify mail for automation discounts.

A five-digit ZIP gets a piece to the right neighborhood. ZIP+4 gets it to the right block face, building, or even a specific mail stop inside a large organization.

That distinction shows up directly in USPS's own definition of a "complete" address, which requires a match against the ZIP+4 database for the finest level of routing accuracy. If your mail volume is high enough to matter, ZIP+4 isn't a nice extra. It's the difference between manual handling and automated sorting.

Common Address Errors That Delay Mail

Most delivery delays trace back to a small handful of repeat offenses, and nearly all of them are fixable in under a minute.

  • Missing or wrong ZIP code, or a city and state pairing that don't actually match. A ZIP tied to the wrong state stops automated sorting cold.
  • Apartment or suite number placed below the street line instead of on it or directly above it.
  • Marketing copy, logos, or slogans printed inside or beneath the address block, which confuses the scanning equipment reading the delivery line.
  • Abbreviating the city name, which USPS never recommends. Cities should always be spelled out in full.

Pro Tip: Run any address you're unsure of through a free ZIP lookup tool before printing labels in bulk. It takes ten seconds and catches mismatches that would otherwise bounce an entire mailing. For a deeper look at how these mistakes compound at scale, see this rundown of common shipping mistakes to avoid.

Formatting a US Address From Outside the United States

Sending a parcel to the US from abroad follows the same domestic layout, with one addition and a few practical adjustments.

  1. Keep the standard USPS line order intact: name, company (if any), street address with unit number, then city, state, ZIP.
  2. Add "USA" or "UNITED STATES OF AMERICA" as the final line, below the city/state/ZIP line, so customs and international sorting hubs immediately identify the destination country.
  3. Use Latin alphabet characters only, and skip local punctuation conventions from your home country. A comma-heavy European format or non-Latin script will confuse both your local postal carrier and the eventual US sorter.
  4. Keep customs documentation separate from the address block. Customs forms belong on the outside of the parcel or in an attached pouch, never written into or beneath the delivery address itself.

For senders working through international postal networks, general guidance on positioning the country line on international mail reinforces the same principle: the destination country always comes last, after the full domestic-style address is complete.

Simply Parcel's Role in Getting US Addresses Right

Booking a shipment through Simply Parcel walks you through the address fields in the order US carriers expect, which cuts down on the guesswork around abbreviations and line breaks.

  • The booking flow separates street, unit, city, state, and ZIP into distinct fields, so you're not left deciding where a suite number goes.
  • Before finalizing a label, double-check the ZIP+4 if your courier partner supports it. A validated ZIP+4 reduces the odds of a scan failure at the US sorting facility.
  • Pay close attention to apartment or suite placement in the booking form. The same rule that governs printed mail (unit number on or above the street line, never below) applies to shipping labels too.

For more on getting the label itself right, this guide to shipping label requirements covers formatting details beyond the address block alone.

Strict USPS Rules vs. Simple Legibility

Businesses sending bulk mail or chasing automation-rate discounts should follow Publication 28 to the letter, since even minor formatting drift can bump a mailing out of its discount tier. Someone mailing a single birthday card has more room to breathe. Legibility and a correct ZIP code matter far more than perfect capitalization for a one-off letter. Either way, keep decorative text and logos off the address block itself. It's the one habit that causes trouble at every volume level.

— Simply

Try Simply Parcel for Validated International Labels

If you're shipping from Singapore to a US address and want one less thing to double-check, Simply Parcel builds the label for you once you enter the destination details, applying the line order and formatting this guide covers automatically instead of leaving it to manual entry. That matters most for businesses sending parcels regularly, where one mistyped ZIP or misplaced suite number can mean a delayed shipment and an unhappy customer on the other end. Compare courier options, get a shipment quote, and book a pickup without re-entering the same address twice across different carrier portals. If you're already mid-shipment, you can check formatting against your existing booking through Simply Parcel's tracking tool before the label prints.

Sources

FAQ

Can You Give Me an Example of a US Address?

A standard example is: JOHN SMITH / 482 N MAPLE AVE / SPRINGFIELD IL 62704-1234, written in all caps with no punctuation for a mailpiece.

How Do I Enter a US Address in a Form or Booking Tool?

Enter the recipient name, then street address including any unit number, then city, then the two-letter state code, then ZIP or ZIP+4. Platforms like Simply Parcel split these into separate fields so the order is handled for you.

How Do I Write a US Address in International Format?

Keep the standard four-line USPS layout, then add "USA" or "UNITED STATES OF AMERICA" as a final fifth line so international sorting facilities and customs can identify the destination country immediately.

How Do You Read a US Address?

Read top to bottom for the recipient and street details, but remember that USPS sorting machines actually process the city, state, and ZIP line first since it anchors the routing decision.

Is ZIP+4 Required on Every US Address?

No, a standard five-digit ZIP works for most personal mail. ZIP+4 is recommended rather than mandatory, and it becomes far more valuable for business or high-volume shipments where precise routing matters.