How to Analyze a Rental Property: Cap Rate and Cash Flow
Quick Answer
Cap rate = annual net income ÷ purchase price. A 6-8% cap rate is good for 2026. Cash-on-cash return = annual cash flow ÷ down payment. Need 3-6% cash-on-cash minimum. Analyze 3-5 properties before buying one; most fail these tests.
The Four Key Metrics
1. Cap Rate (Capitalization Rate)
Formula: Net Operating Income (NOI) ÷ Purchase Price
Example: $300,000 duplex
Gross rent: $2,000/month = $24,000/year
Vacancy (5%): -$1,200
Maintenance (10% of rent): -$2,400
Property taxes: -$3,000
Insurance: -$600
NOI: $16,800/year
Cap rate: $16,800 ÷ $300,000 = 5.6%
Interpretation:
- 5.6% cap rate means property returns 5.6% annually (before mortgage)
- For comparison: 10-year Treasury is 4.2%, stock market is 8-10%
- 5.6% is okay, not great
Good cap rate zones (2026):
- Below 4%: Overpriced (avoid)
- 4-5%: Fair, depends on market appreciation
- 5-7%: Good for income
- 7-10%: Excellent cap rate (need to understand WHY it's so high—could be risky property)
2. Cash-on-Cash Return
Formula: Annual Cash Flow ÷ Down Payment
Same duplex example:
NOI: $16,800
Mortgage payment (80% LTV @ 6.5%, 30 years): -$10,200
Annual cash flow: $6,600
Down payment: $60,000 (20%)
Cash-on-cash return: $6,600 ÷ $60,000 = 11%
Interpretation:
- You invested $60K, property spits out $6,600/year
- That's 11% return on your cash (before appreciation, depreciation deduction)
- This is excellent (beats stock market)
Minimum acceptable: 3-5% cash-on-cash
3. Price-to-Rent Ratio
Formula: Purchase Price ÷ Annual Rent
Same duplex:
- Price: $300,000
- Annual rent: $24,000
- Price-to-rent: $300,000 ÷ $24,000 = 12.5
Interpretation:
- You're paying 12.5 years of rent to own it
- Below 15: Generally good (property is reasonably priced)
- Above 20: Overpriced (rent won't justify purchase)
- 15-20: Depends on local market
4. Debt Service Coverage Ratio (DSCR)
Formula: NOI ÷ Annual Debt Payments
Same duplex:
- NOI: $16,800
- Annual debt service (mortgage): $10,200
- DSCR: $16,800 ÷ $10,200 = 1.65
Interpretation:
- Property generates 1.65x the debt payments
- If rents drop 30%, still covers debt (1.65 - 0.30 = 1.35 cushion)
- Minimum acceptable: 1.2 (most lenders require 1.25+)
- Ideal: 1.5+
Evaluating 5 Properties (Case Study)
Property 1: Urban Multifamily
- Price: $500K, 4-unit
- Rent: $2,200/unit = $8,800/month
- Cap rate: $105,600 ÷ $500K = 21.1% (wait, this is wrong)
Let me recalculate:
- Gross rent: $8,800 × 12 = $105,600
- Vacancy: -$5,280
- Maintenance: -$10,560
- Taxes: -$5,000
- Insurance: -$2,000
- NOI: $82,760
- Cap rate: $82,760 ÷ $500K = 16.6%
That's too high. Something's wrong with pricing or the property is in a bad area. Skip.
Property 2: Suburban SFR
- Price: $350K, single family
- Rent: $2,000/month
- NOI: $20,000 (after all expenses)
- Cap rate: $20K ÷ $350K = 5.7%
- Down payment (20%): $70K
- Cash-on-cash: ($20K - $8,400 mortgage) ÷ $70K = 16.6%
Verdict: Good property. Buy if location is solid.
Property 3: Overpriced City
- Price: $600K, SFR in trendy city
- Rent: $2,200/month = $26,400/year
- Expenses: $8,000/year
- NOI: $18,400
- Cap rate: $18,400 ÷ $600K = 3.1%
Verdict: Overpriced. Buying for appreciation only (risky).
Property 4: Cheap Rural
- Price: $150K, duplex
- Rent: $800/unit = $1,600/month
- Expenses: $300/month
- NOI: $15,600
- Cap rate: $15,600 ÷ $150K = 10.4%
Verdict: Excellent cap rate, but understand WHY it's cheap. Crime? Bad schools? Take the 10% return if local economy is growing.
Property 5: Positive Cash Flow
- Price: $400K, 3-unit
- Rent: $2,500/unit = $7,500/month
- Expenses: $2,000/month
- NOI: $66,000/year
- Cap rate: $66K ÷ $400K = 16.5%
Wait, same issue as Property 1. If cap rate is way too high, re-examine assumptions. Price might be wrong or property might be problematic.
The Red Flags
Red flag 1: Cap rate > 12%
- Why is it so high? Market collapse? Crime area? Bad condition?
- Don't buy without understanding
Red flag 2: Cap rate < 3%
- Buying on appreciation hope only (risky)
- No income cushion
Red flag 3: Price-to-rent > 25
- Price is too high relative to rent
- Rents would need to spike 50%+ for math to work
Red flag 4: DSCR < 1.2
- Little cushion if rents drop
- Risky
Red flag 5: Vacancy assumed at 0%
- Unrealistic
- Use 5-10% vacancy assumption
The Numbers That Matter
Go, no-go decision points:
| Cap rate | Cash-on-cash | Price-to-rent | Decision |
|---|---|---|---|
| 7-10% | 8-12% | 12-15 | BUY |
| 5-7% | 5-8% | 15-18 | Consider |
| 3-5% | 2-5% | 18-25 | Risky |
| <3% | <2% | >25 | SKIP |
Building Your Analysis Spreadsheet
Create a simple Excel sheet:
- Property address
- Purchase price
- Down payment %
- Mortgage amount
- Mortgage rate and term
- Gross annual rent
- Vacancy %
- Maintenance %
- Property tax
- Insurance
- NOI
- Cap rate
- Cash-on-cash return
- DSCR
Calculate all metrics. If not in the "BUY" zone, skip property.
The 1% Rule (Quick Filter)
Rule: Monthly rent should be at least 1% of purchase price.
Example:
- Property $300K
- 1% = $3,000/month minimum rent
- If rent is $2,500, fail the test
- If rent is $3,200, pass the test
This is a rough filter. Use detailed analysis for final decision.
Sources
- NAREIA. (2026). "Rental Property Analysis Guide."
- BiggerPockets. (2026). "Cap Rate and Cash Flow Analysis."
- National Apartment Association. (2026). "Multifamily Property Metrics."
- IRS. (2026). "Rental Property Depreciation and Deductions."
- Federal Reserve Board. (2026). "Mortgage Terms and Rates."