Rental Property Analysis

· 3 min read
Rental property analysis is the process of running the numbers on a potential investment before you buy it — and skipping this step is how…

Rental property analysis is the process of running the numbers on a potential investment before you buy it — and skipping this step is how people end up owning money pits disguised as rental properties.

Good analysis answers three questions: Will this property cash flow? What’s my return on investment? And what are the risks that could blow up my projections? Every number should be conservative because reality always finds ways to be more expensive than your spreadsheet predicted.

Step 1: Estimate Income

Start with market rent — what comparable units in the same area actually rent for, not what the seller claims or what the listing says. Check Zillow, Rentometer, and Craigslist for real comps. Talk to local property managers.

Then apply a vacancy rate. Use 5-8% for strong markets and 8-12% for weaker ones. Include other income if applicable — pet rent ($25-$50/month per unit), laundry ($50-$100/month per building), parking fees, or storage.

Example on a $250,000 duplex:

  • Unit 1 rent: $1,300/month
  • Unit 2 rent: $1,200/month
  • Gross annual rent: $30,000
  • Vacancy (7%): -$2,100
  • Pet rent: +$600
  • Effective gross income: $28,500

Step 2: Calculate Expenses

The “50% rule” says operating expenses (not including the mortgage) roughly equal 50% of gross rent. It’s a decent screening tool but not a substitute for itemizing actual expenses:

  • Property taxes: Pull from county assessor records. Budget for reassessment at purchase price.
  • Insurance: Get actual quotes. Landlord policies cost 15-25% more than homeowner policies.
  • Maintenance (5-10% of rent): Higher for older properties. A 1960s building needs more than a 2010 build.
  • CapEx reserve (5-10% of rent): Roof, HVAC, water heater, appliances. These are when, not if.
  • Property management (8-10%): Budget this even if you self-manage. Your time has value, and you might want to hire a manager later.
  • Utilities (if owner-paid): Water/sewer, trash, common area electric.
  • HOA fees: If applicable. Some HOAs increase dues aggressively.

Step 3: Run the Key Metrics

Cash flow: Income minus all expenses minus mortgage payment. On our duplex: $28,500 income – $13,500 expenses – $12,000 mortgage = $3,000/year ($250/month). Positive, but thin.

Cash-on-cash return: Annual cash flow / total cash invested. If you put in $55,000 (down payment + closing + minor repairs): $3,000 / $55,000 = 5.5%. Modest.

Cap rate: NOI / purchase price. $15,000 NOI / $250,000 = 6%. Reasonable for a duplex in most markets.

1% rule: Monthly rent / purchase price. $2,500 / $250,000 = 1%. Exactly at the threshold. Properties above 1% tend to cash flow; below 1% often struggle.

Step 4: Stress Test

The real analysis happens when you break your assumptions. What if vacancy hits 15%? What if you need a $10,000 roof repair in year two? What if interest rates are 1% higher when you refinance? What if rents drop 5%?

Run each scenario and check: does the property still cash flow? Can you cover expenses from other income if it doesn’t? How many months of vacancy can you sustain before it becomes a financial problem?

A deal that works under best-case assumptions but fails under moderate stress isn’t a deal — it’s a gamble.

Step 5: Verify On-Site

Numbers on a spreadsheet don’t reveal a cracked foundation, knob-and-tube wiring, or a neighborhood that looks fine on Google Maps but feels sketchy in person. Always get a professional inspection and walk the property yourself — or send someone you trust if you’re investing out of state.

Run your analysis with our mortgage calculator for mortgage scenarios, check the renovation ROI calculator if the property needs work, and study up on key metrics in the glossary.