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Load Factor Calculator

Office load factor stacks two layers — floor common area (corridors, restrooms, lobby on the tenant's floor) and building common area (main lobby, mechanical rooms, fire stairs). This calculator computes both and the total load factor that converts usable SF into rentable SF.

Total load factor

1.172

Total add-on %

17.22%

Floor load factor

1.122

Building load factor

1.045

Rentable SF on floor

20,200

Rentable SF (fully loaded)

21,100

How the math works

Load factors stack — floor load (usable + floor common) and building load (floor RSF + building common) multiply to the total load factor. A 1.12 floor × 1.05 building = 1.176 total load. Single-tenant floors skip the floor load entirely.

Tenants on small partial floors pay both loads. Tenants on full floors pay only the building load. That's why partial floors often price at slightly higher effective $/USF despite identical headline $/RSF.

How to Use

  1. Enter usable SF inside the tenant premises.
  2. Enter floor common SF (corridors, elevator lobby, restrooms on that floor).
  3. Enter building common SF (main lobby, mechanical, pro-rata).
  4. Read the stacked load factors.

Frequently Asked Questions

Floor load vs building load?

Floor load applies to partial-floor tenants. Building load is everyone's share of the main lobby, fire stairs, mechanical. Full-floor tenants avoid the floor load because they 'own' the whole floor's common areas.

BOMA 2017 changes?

BOMA 2017 aligned with international IPMS standards — slightly different treatment of mechanical and service areas. Most Class A buildings have re-measured under 2017 standards by now.

How does this affect rent negotiation?

Tenants should quote effective rent per USF, not RSF, when comparing buildings. A 1.12 load building at $32/RSF is $35.84/USF; a 1.18 load building at $31/RSF is $36.58/USF — the 'cheaper' building is actually more expensive.

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