# Address Line 2: What Goes There and What Doesn't

> Address line 2 holds whatever narrows the street address down to your door: apartment, suite, unit, floor, room or building name, sometimes a c/o name. It is optional. If you live in a house with its own number, leave it empty. The street number and name always belong in address line 1.

- URL: https://address-valid.com/address-formats/address-line-2/
- Language: en
- Updated: 2026-10-19
- Publisher: AddressValid (OnlineBuilders LLC, https://onlinebuilders.biz)

The HTML standard that browsers use for autofill gives exactly one example for address line 2: `MIT Room 32-G524`. Just a room in a campus building. That tiny example says more than most help pages, because it shows what the field is for. It is the part of an address that gets you from the building to the right door.

Forms split addresses into two lines because a single street field gets crowded. Line 1 carries the house number and street. Line 2 carries the rest of the "where inside" information. Postal services, however, mostly do not think in lines 1 and 2. They have their own rules on where that information sits, and those rules differ by country.

## What belongs in address line 2

Anything that subdivides the street address:

| Type | Example entry | Common in |
|---|---|---|
| Apartment or flat | `Apt 4B`, `Flat 3` | US, UK |
| Suite or office | `Ste 201`, `Office 12` | Business addresses everywhere |
| Unit | `Unit 7` | US, Canada, Australia |
| Floor | `Fl 3`, `3rd floor` | Office buildings |
| Building name or number | `Victoria House`, `Bldg C` | UK, campuses, business parks |
| Room | `Room 32-G524` | Universities, hospitals |
| Care of | `c/o Martin Weber` | Guests, temporary stays |

Two things that people also type into line 2 are fine on paper but cause trouble later: company departments ("Accounts payable") and gate codes. Departments really belong in a company or attention line. Gate codes are delivery notes, not address data.

## What does not belong there

Typical misuse looks like this:

- Line 1 copied into line 2, so the label prints the street twice.
- The house number in line 2 and only the street name in line 1.
- The city or postcode, typed because the form did not make the next fields obvious.
- A phone number, an email address or "N/A".
- Delivery instructions such as "ring twice" or "leave with neighbour".

Each of these breaks something. Duplicated streets look odd but usually arrive. House numbers in the wrong field are worse: address-matching software reads line 1 as the delivery line, finds no number, and flags the record as undeliverable. Our [address format checker](https://address-valid.com/address-checker/) catches the missing number case, because it looks for a house number in the street field.

## Where the unit ends up on the envelope

Here is the part most forms ignore. Collecting the unit in a separate field is fine, but the label should follow the destination country's postal rules, not the form's layout.

**Where the apartment or unit goes when the address is printed**

| | United States | United Kingdom | Canada | Germany |
|---|---|---|---|---|
| Preferred position | End of the street line | Own line above the street | Before the street number, joined by a hyphen | After house number, or own line |
| Example | `123 MAIN ST APT 4B` | `Flat 3` / `27 Harbour Road` | `10-123 MAIN ST NW` | `Rhondorfer Str. 666 // Appartment 47` |
| Designator word needed | yes | yes | no (hyphen form) | partly |

Source: USPS Publication 28 §213; Royal Mail, Canada Post and Deutsche Post entries in the UPU address catalogue; Canada Post Addressing Guidelines

For the US, [Publication 28 section 213](https://pe.usps.com/text/pub28/28c2_003.htm) says the preferred location of the unit is the end of the delivery address line. Only when that line is full should the unit move to the line immediately above. So a checkout that collected `123 Main St` and `Apt 4B` should print `123 MAIN ST APT 4B`. Printing the apartment on a line underneath the street, as some label templates do, is the one placement USPS does not describe.

The UK works the other way round. Royal Mail data stores flats as sub-buildings, and the clean address block puts `Flat 3` or the building name on its own line above the street. Our [UK address format guide](https://address-valid.com/address-formats/uk-address-format/) has more detail.

Canada has the most compact rule. Canada Post's guidelines allow three positions, and the first is a unit number in front of the civic number with a hyphen: `10-123 MAIN ST NW`. That form leaves out "APT" entirely. The other two options are a unit designator after the street type, or the unit on the line above.

Germany has no single field for it. The Deutsche Post entry in the UPU catalogue shows `Rhondorfer Str. 666 // Appartment 47` for a flat, two slashes and all. On domestic German mail you will more often see the name of a person the mail goes via (`c/o`) or a building part like `Hinterhaus` on a separate line between name and street. The [German address format](https://address-valid.com/address-formats/german-address-format/) article goes into this.

## A worked example: one form, four labels

Say a shop's form collected these fields:

```
Name:            Dana Kim
Address line 1:  4500 Riverside Drive
Address line 2:  Suite 210
City:            Springfield
State:           VA
ZIP:             22162
```

Printed in USPS style, the block becomes three lines:

```
DANA KIM
4500 RIVERSIDE DR STE 210
SPRINGFIELD VA 22162
```

Line 2 vanished into line 1, the suffix got its standard abbreviation and the punctuation went. Nothing was lost. The opposite case, a UK customer with `Flat 3` in line 2, keeps four or five lines, because there the flat stays on its own line above the street. The street address and suite in this example are invented to show the transformation.

## How to label the field on your own form

The field name "Address line 2" tells customers nothing. Labels that say what you want work better: "Apartment, suite, unit, building, floor (optional)". Mark it optional, so people in houses do not invent something to fill it.

For autofill, use the standard `autocomplete="address-line2"` token from the [WHATWG HTML specification](https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#autofill), together with `address-line1` on the first field, both prefixed with `shipping` or `billing` if you collect two addresses. Browsers then fill the right values without guessing. If you add address autocomplete on top, check that the suggestion keeps the unit; suggestion lists often return the building and drop the apartment. That gap is the main topic of our article on [address autocomplete in the checkout](https://address-valid.com/validation/address-autocomplete-checkout/).

On the database side, keep line 2 as its own column but run a cleanup that moves obvious unit patterns (`APT`, `STE`, `UNIT`, `#`, `Flat`) out of line 1 into line 2 and the reverse for house numbers. It is a small script, and it removes a whole class of matching failures. If the job grows beyond a script, for example across several shops and a CRM, a data engineering partner like [OnlineBuilders](https://onlinebuilders.biz/solutions/software-development) can build the pipeline.

For now, open your last export of shipping addresses, filter on line 2, and look for street names, cities and phone numbers. That list is your cleanup backlog.

## FAQ

### Can I leave address line 2 empty?

Yes. It is optional in almost every form, and a single-family house with its own street number does not need it. Leaving it empty is better than repeating line 1 or filling it with the city.

### Should I write Apt, # or Unit in address line 2?

In the US, use the designator that matches your building, usually APT, STE or UNIT. USPS treats the pound sign as a fallback for when the right word is unknown. In Canada, the shortest correct form puts the unit number in front of the street number with a hyphen instead.

### Is a PO box address line 1 or line 2?

Line 1. A PO box replaces the street address, so it goes in the main field. Putting a PO box in line 2 under a street address creates a dual address, and USPS delivers to the address on the line directly above the city line.

### Can I put delivery instructions in address line 2?

Better not. Text like leave at back door gets printed into the address block and can confuse sorting software. Use a separate delivery notes field if the shop offers one.

Photo: Marek Ślusarczyk (Tupungato) Photo portfolio, CC BY 3.0 (https://commons.wikimedia.org/wiki/File:04_Mailboxes_in_lobby_of_apartment_building_in_Spain,_common_area_in_apartment_building.jpg)