Office Loss Factor and Load Factor Explained for RE Interviews
Loss factor vs load factor in office leasing interviews: usable vs rentable SF, how landlords quote rent, and how it changes effective occupancy cost.
REPE · 5 min read
Office interviews love loss factor and load factor because tenants feel rent on usable space while leases charge on rentable space. Students search these terms the night before RE interviews. The pass bar is translating a rentable quote into usable economics without mixing the formulas.
The short answer
"Usable SF is space the tenant actually occupies. Rentable SF adds a share of common areas. Load factor relates rentable to usable. Loss factor describes how much of rentable is lost to common area allocation. Landlords quote rent on rentable SF, so comparing buildings requires translating to usable economics."
Formulas (know both conventions)
Common relationships
Load Factor ≈ Rentable SF ÷ Usable SF Loss Factor ≈ (Rentable − Usable) ÷ Rentable Usable ≈ Rentable × (1 − Loss Factor)
Exact definitions vary by market measurement standards. Say you would confirm BOMA version and local practice before you trust a broker stack of comps. Interviewers like that humility more than fake precision.
Why it matters in underwriting
| Quote | Risk if ignored |
|---|---|
| $50 / rentable SF | Looks cheaper than $55 elsewhere |
| Higher loss factor | More dollars for the same desk space |
| Renovation changing common area | Load shifts mid-hold |
| Spec suites and shared amenities | Measurement fights with tenants |
Landlords market efficiency and views. Tenants care about cost per person and cost per usable foot. Brokers sometimes quote aggressively on rentable while soft-pedaling loss factor. Your job in an interview is to show you will normalize.
Mini example
Usable 10,000 SF. Rentable 12,000 SF.
Load factor = 12,000 / 10,000 = 1.20.
Loss factor = 2,000 / 12,000 ≈ 16.7%.
Face rent $40 per rentable SF → annual rent $480k → $48 per usable SF.
Load
1.20x
Loss
~16.7%
$/usable
$48
Say the competing building quotes $42 rentable with load 1.10. Annual rent on 10,000 usable is $42 × 11,000 = $462k, or $46.20 per usable. The "cheaper" $40 building can lose on usable economics depending on load. That comparison is the interview point.
Loss vs load without getting cute
People mix the words. Keep a clean distinction:
- Load factor greater than 1.0 scales usable up to rentable
- Loss factor is the share of rentable that is common-area allocation
If load is 1.25, rentable is 25% above usable. Loss is not automatically 25%. Loss on that example is (1.25U - U) / 1.25U = 0.20, or 20%. Mixing those percentages is a common fail.
Rentable divided by usable. Easy multiplier for converting a floor plate into billed SF.
Common area share of rentable. Easy way to explain how much billed SF is not private demised space.
Process for interview problems
Label the inputs
Write usable, rentable, face rent, and which SF the rent applies to.
Compute both factors
Show load and loss so the interviewer sees you know both conventions.
Normalize to usable
Convert annual occupancy cost to dollars per usable SF before ranking buildings.
Add lease economics
Layer free rent, TI, and operating expenses after the SF translation so you do not fix one illusion and keep another.
Owner and lender angle
For landlords, higher load can improve revenue on the same demised footprint if the market accepts the measurement standard. Push it too far and leasing velocity suffers. For lenders and REPE underwriters, rent rolls should state rentable SF consistently, and comps should be apples-to-apples on measurement. In distressed office, vacated floors and reconfigured common areas can change effective load mid-business plan. Flag that as an ops and leasing diligence item.
Interview verbal
"Rentable includes allocated common area. Usable is the space you sit in. Load and loss factors translate between them. I compare tenant cost on a usable basis and I confirm the measurement standard before I trust a comp."
Tie-out to net effective rent
Loss and load are only the first filter. After you normalize to usable SF, layer free rent, tenant improvements, and operating expense structure. A building with a friendly load factor can still lose on net effective cost if TI is thin and expenses are heavy. In interviews, say the sequence out loud: measurement first, then lease economics, then credit and downtime.
That sequencing keeps you from debating pennies of face rent while missing a 20% load gap or a free-rent bridge that changes year-one cash yield.
Common traps
- Comparing face rents without converting to usable
- Treating loss percent and load percent as interchangeable
- Ignoring that TI and free rent still need the same SF basis
- Forgetting measurement standard changes after renovations
- Quoting efficiency as a vibe instead of a factor
Follow-ups you should expect
| Follow-up | Clean direction |
|---|---|
| Why quote rentable? | Market convention; common areas are real building cost |
| Which factor do brokers use? | Both appear; define before you debate |
| How does this hit NOI? | Through rentable SF times in-place rents, consistently measured |
| Does higher load mean better building? | Not by itself; tenants judge usable cost and layout quality |
| BOMA? | Measurement standard; confirm version and local practice |
Related
Office Underwriting, Gross vs Net Effective Rent, Distressed Office case.
Practice on SheetRank
On office cases, force every rent quote through a usable conversion before you call a building cheap. That habit prevents false comps.
Practice on SheetRank
Apply what you learned with drills, guided Academy builds, and live deal underwriting.