CrunchLease

Load Factor Calculator

See what a quoted $/RSF rate really costs per usable foot — and compare two buildings side by side.

SF
%
$/RSF/yr

Optional — leave at 0 to hide the cost-impact output.

Results

Rentable SF (RSF)
5,750
Usable SF (USF)
5,000
Load factor
15.00%
Loss factor
13.04%
Effective rent
$34.50 /USF/yr · $2.88 /USF/mo

Benchmarks reviewed 2026-07-08.

Usable vs rentable square feet

Usable square feet (USF) is the space your team actually occupies — offices, workstations, your private restrooms. Rentable square feet (RSF) adds your share of the building’s common areas: lobbies, shared corridors, mechanical rooms. Landlords quote rent on RSF, but you can only work in USF, so RSF is what you pay for and USF is what you get.

Load factor vs loss factor (the two conventions)

Both numbers describe the same gap between rentable and usable area — they just divide it differently, and different markets quote different ones.

load factor = RSF / USF − 1
loss factor = (RSF − USF) / RSF = load factor / (1 + load factor)

Most US markets quote the load factor (the add-on to your usable area). New York and the tristate market quote the loss factor (the share of rentable area you can’t use). This calculator always shows both so a “15% load factor” and a “13% loss factor” building can be compared apples-to-apples.

What a quoted rate really costs per usable foot

A $30/RSF quote isn’t $30 for space you can use. Multiply by the load factor to get the effective rent on the space you actually occupy:

effective $/USF/yr = quoted $/RSF/yr × (1 + load factor)

At a 15% load factor, $30/RSF is $34.50/USF/yr — the number to use when you compare buildings. If you’re also weighing base rent against pass-through costs, run the space through the Triple Net (NNN) Lease Calculator next, and use the Net Effective Rent Calculator to fold in free rent and TI.

Comparing two buildings with different load factors

The building with the lower face rate isn’t always cheaper. Switch on Compare two buildings to hold your usable square footage constant and see the effective cost per usable foot side by side — the comparison that actually decides the deal.

Typical load factors by building type

Ranges depend on the measurement standard and how much amenity space a building carries. BOMA 2024 is the current standard: it now counts some outdoor amenity space as rentable, while tenant balconies and terraces no longer carry a load factor (Appendix A.4):

Building typeTypical load factor
Single-tenant / efficient8–12%
Multi-tenant office (typical)10–25%
Heavy-amenity25%+ (unusual — investigate)
Industrial0–5%

Investors sizing a whole building instead of a single suite will want the Cap Rate Calculator for the value side of the same deal.

Frequently asked questions

What is a good load factor?

For multi-tenant office, 10–25% is typical, and single-tenant or efficient floors run lower at 8–12%. Anything above 25% is unusual and worth investigating. "Good" depends on what the common areas buy you — a heavy-amenity building can justify a higher factor if the lobby, fitness center, and conference space genuinely serve your team. Compare the effective cost per usable foot, not the load factor in isolation.

What's the difference between load factor and loss factor?

They measure the same gap between rentable and usable area from opposite ends. Load factor = RSF/USF − 1, the add-on to your usable space. Loss factor = (RSF − USF)/RSF, the share of rentable area you can't use. A 15% load factor equals a 13% loss factor. Most US markets quote load factor; New York and the tristate area quote loss factor.

How is rentable square footage measured (BOMA)?

Most US office buildings use a BOMA standard, which adds a share of building common areas to your usable space to arrive at rentable area. Different BOMA editions and measurement methods produce different numbers, so always ask which standard a quote uses before comparing two buildings.

Why am I paying for space I can't use?

Rentable square footage bundles your usable suite with a pro-rata share of lobbies, corridors, restrooms, and mechanical rooms — space everyone in the building relies on but no single tenant occupies. It's the standard way landlords recover common-area cost. The load factor tells you how much of your rent goes to that shared space.

Do industrial leases have load factors?

Usually very little — industrial and warehouse space typically carries a 0–5% load factor because there's minimal shared common area. Office build-out inside a flex or industrial building can add a modest load factor on the office portion, but the warehouse itself is generally leased close to its usable footprint.

Related calculators

Triple Net (NNN) Lease Calculator Add base rent, taxes, insurance, and CAM to see the true all-in cost of an NNN lease. Net Effective Rent Calculator Turn face rent, free rent, and TI concessions into a single effective rent figure. Cap Rate Calculator Solve cap rate, value, or required NOI, and stress-test value with a sensitivity matrix.