The number is not the answer. Which assumption it rests on is.
Change an input and everything recomputes from the rent roll. What you are looking for is not where the deal lands but what it is standing on — because that is the thing worth negotiating about.
Everything derives from one table, so everything moves together
Because NOI comes out of the rent roll rather than sitting beside it, a change to one assumption propagates through the cash flow, the coverage tests and the exit at once — with no second set of numbers that can quietly disagree.
- Growth, vacancy, exit, loan termsBuilding-level assumptions and per-suite re-leasing assumptions, all editable, all feeding the same monthly model.
- Re-running is cheap, so sweep by handSet a value, look, set another. There is no sensitivity grid rendered for you — what there is, is a model fast enough that you do not need one.
- Watch which figure actually movesAn assumption that swings the IRR four points and one that swings it by ten basis points are not equally worth arguing over.
Total equity required
$6,200,000
Cash-on-cash (yr 1)
6.65%
Levered IRR
14.24%
Exit value
$21,940,000
Net operating income by hold year
The first test to run, every time
Set the exit cap rate equal to the rate you are buying at, and look again.
If the deal only clears your threshold with compression, you are not buying an income stream — you are taking a position on the market. That can be a perfectly reasonable thing to do. It should be a decision rather than a side effect of a default.
The exit is the least knowable input in the model and frequently the largest driver of the return, which is an uncomfortable combination and the reason it deserves more suspicion than it usually gets.
Test the structure, not just the returns
Changing the loan does not only move the equity cheque. It moves which lender test is binding, and that determines what there is to negotiate at all.
- Stretch the amortization and watch debt yield ignore youCoverage improves, debt yield does not move a basis point. If that is your constraint, the term conversation is a dead end.
- Then check the month interest-only endsCoverage during an IO period and coverage after it are different numbers on identical income, and only one of them appears in most models.
Debt — 24 months interest-only
DSCR, IO period
1.71x
Interest only, months 1–24
DSCR, after IO
1.43x
Amortizing, months 25+
Debt yield
11.11%
Unchanged — IO does not move it
LTV
65.0%
$10,890,000 loan
- Payment, IO period
- $58,988
- Payment, amortizing
- $70,460
- Rate / amortization
- 6.50% / 30 yr
- Balance at year 5
- $10,435,324
Same income, same loan, two different coverage ratios depending on which month you look at.
Questions people ask
Which assumptions can I change?
Rent growth, vacancy, operating expense growth, the exit cap rate, the hold period, every loan term, and the per-suite re-leasing assumptions — market rent, renewal probability, downtime, free rent, TI and commission. Everything downstream recomputes from the rent roll.
Is there a sensitivity matrix?
No. You set one value at a time and the model recomputes, which is fast enough to sweep a range by hand but is not a grid of outcomes rendered for you. Worth being precise about, because those are different features and one of them we do not have.
What should I test first?
The exit cap rate, because it is the least knowable input and frequently the largest driver of the return. Set it equal to your entry cap and see whether the deal still clears. If it only works with compression, you have learned what you are actually buying.
What does sensitivity actually tell me?
Which assumption the deal is standing on. A deal that survives a 50 basis point move in the exit cap but falls apart if one tenant does not renew has a tenant problem, not a market problem — and those get negotiated in completely different ways.
Does changing an assumption affect the AI analysis?
Yes. The analysis reads the completed underwriting, so re-running it after a change gives you a read on the deal as it now stands rather than as it stood when you first built it.
Where this goes next
Cash flow modeling
What recomputes when you change something.
Exit & sale modeling
The assumption most worth testing.
Exit cap rate explained
Why it deserves more suspicion than it gets.
IRR calculator
What the timing of each dollar is worth. Free tool.
Size the loan
Testing the debt side specifically.
Check an asking price
The test that starts the conversation.
Find out what your deal is standing on.
Build it from the documents, then change one assumption at a time and watch what actually moves. Free plan, no credit card.