When shipping to an apartment, suite, office, or any multi-unit building, how you enter the unit number in Address Line 2 matters. Carriers — including USPS, UPS, FedEx, and DHL — rely on standardized unit designators to confirm the delivery location and route the package to the correct door.
This article explains what a unit designator is, which ones are accepted, and how to format Address Line 2 correctly in Deliveri so your shipments are validated and delivered without issue.
When Deliveri validates a shipping address, it checks the full address — including the unit number — against USPS delivery records. If the unit number is missing or formatted incorrectly, the address may fail validation, which can lead to:
Delayed or returned shipments
Failed delivery attempts
Additional carrier surcharges for address corrections
Adding the correct designator before the unit number (e.g. APT 4B instead of just 4B) significantly improves address confirmation rates and reduces the chance of a delivery problem.
A unit designator is the abbreviation that tells the carrier what type of secondary location you're referring to — apartment, suite, floor, room, etc. It must appear before the unit number on Address Line 2.
✅ Correct: APT 4B | ❌ Incorrect: 4B |
✅ Correct: STE 200 | ❌ Incorrect: Suite200 or #200 |
The following are the most common designators recognized by USPS. Using the standard abbreviation (right column) is preferred over spelling it out in full.
Unit Type | Standard Abbreviation |
Apartment | APT |
Building | BLDG |
Floor | FL |
Suite | STE |
Unit | UNIT |
Room | RM |
Department | DEPT |
For a full list of approved designators, refer to USPS Publication 28 — Section 213.
When entering an address in Deliveri, use Address Line 2 for all unit information. Always follow this format:
[Designator] [Unit Number]
Examples:
What you're entering | Correct format |
Apartment 4B | APT 4B |
Suite 200 | STE 200 |
Floor 3 | FL 3 |
Unit 12 | UNIT 12 |
Room 108 | RM 108 |
Building 14 | BLDG 14 |
USPS discourages using # as a unit designator when the correct abbreviation is known. If you do use it, there must be a space between # and the unit number (e.g. # 72, not #72). However, when possible, use the standard abbreviation instead — it produces better address validation results.
Deliveri uses Google Maps Address Validation to verify shipping addresses in real time. When a unit number is involved, the system checks:
Whether the primary address (street + number) exists according to USPS
Whether the unit number provided matches a known sub-premise at that address
If your unit number is missing entirely, Deliveri will prompt you to add one. If the unit number is present but doesn't match USPS records, Deliveri will ask you to double-check and correct it before proceeding.
In some cases, an address can pass Google's address validation — meaning it exists and is recognized — but USPS does not deliver to that location. This is common for rural routes, commercial zones, private communities, or addresses serviced exclusively by private carriers.
When this happens, Deliveri will display an informational notice letting you know that USPS does not deliver to the address. This does not block you from purchasing a label. It simply means:
USPS shipping rates will not be shown for that shipment
You can still purchase a label through any other carrier that services the address, such as UPS, FedEx, or DHL
Deliveri automatically filters the available carrier rates to only show options that can deliver to the confirmed address. You do not need to take any additional action — just select from the available rates and proceed as normal.
Deliveri validates addresses using Google Maps Address Validation, which draws on USPS delivery data for US addresses.
If Address Line 2 is left blank for a known multi-unit building, Deliveri will surface an alert asking you to add a unit number before purchasing a label.
If the unit number you entered doesn't match USPS records, Deliveri will flag it — but you can still proceed if you've confirmed the address directly with your customer.
If an address is validated but USPS does not deliver to it, Deliveri will hide USPS rates and only show carrier options that service that address. You can still purchase a label through other available carriers.
Formatting Address Line 2 correctly improves address confirmation rates across all carriers, not just USPS.
Address Line 2 is optional for single-unit buildings. Only add it when the shipment is going to a specific unit within a larger building.
Using the standard abbreviation (APT, STE, UNIT, etc.) is strongly preferred. Abbreviations match USPS records more reliably and reduce the chance of a validation warning. Spelling it out (e.g. "Apartment" instead of "APT") may still work in most cases but is not the recommended format.
If the unit number isn't available, confirm it with your customer before purchasing a label. Shipping to a multi-unit building without a unit number increases the risk of a failed delivery. Deliveri will surface a warning in this case.
You can, but it's not recommended. USPS prefers the standard unit designator abbreviation over the pound sign when the correct designator is known. Using # may still pass validation in some cases, but STE 200 will perform better across carriers.
This means the unit number you entered doesn't match what USPS has on file for that building. Common causes include a typo, an incorrect unit number, or a newer building not yet fully indexed by USPS. Confirm the unit number with your customer and update Address Line 2 before proceeding.
Yes. While the designator rules come from USPS postal standards, correct formatting improves address confidence for all carriers Deliveri supports, including UPS, FedEx, and DHL.
This means USPS does not deliver to that address, even though the address itself is valid. This is common for certain rural, commercial, or privately serviced locations. You can still purchase a label through any other carrier that services the address — Deliveri will automatically show the available options. USPS rates are simply excluded for that shipment.
How to Validate a Shipping Address in Deliveri
Understanding Address Validation Alerts
How to Purchase a Shipping Label
Not sure how to format a specific address or seeing a validation error you can't resolve? Reach out and we'll help you get it sorted. Contact Deliveri support through live chat or email [email protected].
