Residential Rental health calculator

Landlords get judged on coverage and leverage, not on whether the tenant paid on the first. Scheduled rent is a story. Collected rent, vacancy, maintenance, and debt service are the file. This calculator speaks that file’s language: DSCR, cap rate, cash-on-cash, LTV, collection rate.

Who this is for

Small portfolios, house hackers, and owners of a duplex or a handful of long-term units. It is not an institutional ARGUS model. It is the napkin math a community lender will still recognize.

What to enter first

Monthly rent collected, operating expenses, mortgage payment, units, and — when you have them — NOI and a value estimate. Vacant days and scheduled vs. collected rent keep you honest. Property value can be a conservative Zillow-style guess; label it as such in your own notes.

Worked example: owner-occupied duplex, both sides rented after a refinance

Original example. One building, two units, 12-month lookback.

  • Scheduled rent:
  • Actually collected: $36,480 (one unit empty 18 days; two late months partially recovered)
  • Operating expenses excluding mortgage (tax, insurance, maintenance, water): $9,600 / year
  • Mortgage (P&I): $2,150 / month = $25,800 / year
  • Annual NOI if we treat opex as $9,600 and use collected rent: 36,480 − 9,600 = $26,880
  • Value estimate: $410,000
  • Loan balance: $318,000
  1. Collection rate = 36,480 ÷ 40,800 = 89.4%. The healthy band we use starts near 97%. This building failed the “tenants always pay” story.
  2. DSCR ≈ 26,880 ÷ 25,800 = 1.04×. Many small rental conversations start around 1.25×. This refinance looks tight once vacancy is real.
  3. Cap rate = 26,880 ÷ 410,000 = 6.6% using collected-rent NOI. Using scheduled rent would have printed a prettier lie.
  4. LTV = 318,000 ÷ 410,000 = 77.6%.
  5. Cash flow after debt ≈ 26,880 − 25,800 =

If you only enter scheduled rent, the calculator will flatter you. Enter collected rent and vacant days. That is the whole point of this page.

How to read the results

DSCR asks whether the property pays its debt. Cap rate is unlevered yield. Cash-on-cash needs your actual cash in the deal. Collection and vacancy tell you whether the rent roll is a document or a wish. Watch status means stress-test a vacancy before you buy the next door.

Mistakes that make the math useless

  • Using gross scheduled rent as NOI.
  • Forgetting capex (roof, HVAC) because it was “unusual.” Unusual is the job.
  • Mixing personal house expenses with the rental side of a house hack without saying so.

When to re-run the check

After a rent increase, a refinance, a capital project, or a vacancy streak. Pair it with Seeking a Loan when you want DTI and the rest of the household file in one view.

I have four properties. One calculator or four?

Run each property if you need DSCR per loan. Sum them in a second pass if you want a portfolio snapshot. Lenders often ask both.