Define: Suite Number

A suite number is the unique identifier assigned to a specific leased space, office, or unit within a larger building or business address. It appears on the second address line (often shown as "Suite," "Ste," or the "Apt/Suite/etc." field) to route mail, deliveries, and visitors to the correct unit.

Legal accuracy standard set & glossary spot-checked by Imad Mohammed Nazar , Skadden-trained M&A lawyer, Legal Engineer at GenieAI

Suite number in a commercial lease

In a commercial lease, the suite number does more than help mail arrive. It legally identifies the premises the tenant is renting. The lease will usually describe the leased space by its suite number, floor, and approximate square footage, which fixes the boundaries of what the tenant occupies and pays rent on.

Because the suite number defines the space, getting it right matters. If a lease lists Suite 405 but the tenant actually occupies Suite 407, the mismatch can create disputes over rent, maintenance, and access. That's the kind of detail an accurately drafted contract should get right the first time.

Suite number, unit number, and apartment number

Suite number, unit number, and apartment number often mean the same thing: an identifier for one space within a larger building. The label tends to follow the building type. "Suite" is common in commercial and office buildings, "unit" appears in mixed-use and retail settings, and "apartment" is used in residential buildings. On many online forms all three are grouped under a single field, which is why you'll see "Apt/Suite/etc." as the prompt.

Keeping a suite number private and accurate

A suite number is part of your business address, so treat it with the same care as any contact detail you share. When you add it to a checkout, directory, or supplier account, check the service's privacy policy to see how your address data is stored and used. Keeping the suite number current also matters after a move: update it on your business listings, your Google Business Profile, and with postal carriers so mail and deliveries keep reaching the right unit rather than the previous tenant.

Relevant Circumstances

When an entity is leasing a commercial office space in a multi-story building.
When an entity is renting a suite in a shared office building.
When an entity sublets a suite within a larger leased property.
When an entity rents or leases a suite within a co-working space.

Relevant Sectors

Real Estate
Co-Working Spaces
Commercial Properties
Property Management

A suite number identifies one specific unit or leased space inside a larger building or business address.
It's the detail entered in the "Apt/Suite/etc." field, usually on the second address line (shown as "Suite" or "Ste").
It routes mail, packages, and postal deliveries (including USPS) to the correct tenant so items aren't left at the wrong unit.
In leases, the suite number defines exactly which space a tenant occupies and pays for.
It's distinct from a street number, which identifies the whole building rather than a unit within it.

What is a suite number?

A suite number is the unique identifier assigned to a specific leased space or unit within a larger building. Where a street number tells you which building an address points to, the suite number tells you which office, floor, or tenant space inside that building. It's the piece of a business address that separates one occupant from every other occupant at the same street location.

When you fill out a form and see a field labeled "Apt/Suite/etc." or "Suite/Unit," the suite number is what goes there. On mail and shipping labels it usually sits on the second address line, often abbreviated as "Ste" or written out as "Suite."

Why does a suite number matter?

In a multi-tenant building, dozens of businesses can share the same street address. The suite number is what lets a carrier, a client, or a courier find the right door. Without it, mail and deliveries can end up at the wrong unit or get returned. For that reason, most address forms treat the suite number as a required part of a complete business address, and postal services like USPS use it to sort and deliver each item to the correct suite address.

The suite number also carries weight in contracts. In a commercial lease, the leased premises are defined by their suite number, so it's the detail that fixes exactly which space a tenant is renting, paying for, and responsible for maintaining.

Where you'll come across a suite number

Mail and postal deliveries. Used to route letters, packages, and courier deliveries to the correct unit within a shared building.
Business address listings. Included when a company registers or lists its address, including on Google Business Profile and similar directories, so customers and contacts reach the right office.
Online forms and checkout. Entered in the "Apt/Suite/etc." or second address line field during a search or checkout to complete a delivery address.
Contracts and leases. Used to describe the exact premises a tenant occupies.

How to find or format a suite number

If you're unsure of a suite number, check the building directory, the lease agreement, or ask the property manager or landlord to confirm the correct unit. When you add it to an address, keep the street address on the first line and put the suite number on the second line, for example "Suite 400" or "Ste 210." Some buildings tie the suite number to the floor, so Suite 305 sits on the third floor, while others assign numbers sequentially. For international shipments, put the suite number where the destination country's postal format expects the unit detail, so an overseas carrier can still route it correctly.

When you enter your suite number online, only share it with services you trust. A supplier's privacy policy should explain how it stores and uses your address data, so it's worth a quick look before you hand over a full delivery address.

How it works in practice

Take a design agency that leases office space in a shared commercial building at 120 Market Street. The building holds around 40 separate businesses, all sharing that single street address. The agency's leased unit is on the fourth floor, and the landlord has assigned it the suite number 405.

The agency's full business address reads:

Line 1: 120 Market Street
Line 2: Suite 405 (the "Apt/Suite/etc." field)
Line 3: San Francisco, CA 94103

When a client ships signed documents, the carrier reads 120 Market Street to reach the building and Suite 405 to reach the right door. If the suite number were left off, the delivery could sit in the lobby or go to the wrong unit. In the agency's lease, the same suite number defines the exact premises it rents, so there's no ambiguity about which space is covered.

Suite number vs street number

These two are often confused because both appear in the same address, but they point to different things.

Suite number	Street number
Identifies a specific unit or leased space inside a building.	Identifies the whole building along a street.
Sits on the second address line, e.g. "Suite 405."	Sits on the first address line, e.g. "120 Market Street."
Entered in the "Apt/Suite/etc." field.	Entered as part of the main street address.
Multiple tenants can share one street number but each has a different suite number.	One street number can cover many suites.