Underwrite
Rental property calculator: underwrite the whole deal
Most “rental calculators” either hide the formula or force an account. This page is a deal sheet: purchase and loan assumptions in, operating stack in, three return metrics out — cap rate, cash flow, and cash-on-cash — so you can say pass or pursue before you waste a weekend.
Assumptions
Returns stack
- NOI
- —
- Cap rate
- —
- Monthly CF
- —
- Cash-on-cash
- —
- Cash invested
- —
When to use
First serious look at a listing, comparing two addresses with the same expense rules, or replacing a fragile spreadsheet you don’t trust.
When not to
This is not Zillow rent or an AVM — you type the rent. Don’t treat year-one cash flow as a 30-year promise.
Assumptions: You bring rents, expenses, and loan terms. No address API, no signup wall, no secret market data.
Worked examples
Input
$320k price · 20% down Rent $2,400 Standard OpEx / vacancy
Output
Cap · CF · CoC stack
Check whether monthly cash flow clears your minimum before you chase the kitchen.
Input
Vacancy 8% Management 8%
Output
CoC compresses
Sensitivity is the point — stress the soft assumptions.
Common traps
- This is not Zillow rent or an AVM — you type the rent.
- We win on transparency and no signup, not on “secret market data.”
- Don’t treat year-one CF as a 30-year promise.