By LocateMyWealth · Published
Cash Flow Basics
Cash flow is the money left over after all expenses are paid. It's the lifeblood of rental property investing.
The Basic Formula
Monthly Cash Flow = Gross Rent - All Expenses - Mortgage Payment
Or more detailed:
Cash Flow = Rental Income - Operating Expenses - Debt Service
Where:
- Rental Income = Rent + other income (laundry, parking, etc.)
- Operating Expenses = Everything except mortgage
- Debt Service = Principal + Interest (P&I)
Income Calculation
Gross Potential Rent
The maximum rent if 100% occupied, 12 months.
Vacancy Allowance
Reduce by expected vacancy rate:
- Stable SFH market: 5%
- Multi-family: 8-10%
- Student housing: 15-20%
Other Income
- Laundry: $20-50/month per unit
- Parking: $25-100/month
- Pet rent: $25-50/month
- Storage: $25-75/month
Effective Gross Income Formula
Effective Gross Income = (Gross Potential Rent × (1 - Vacancy Rate)) + Other Income
Expense Breakdown
Fixed Expenses (Predictable)
| Expense | Typical Range |
|---|---|
| Property Taxes | 1-2% of value/year |
| Insurance | 0.5-1% of value/year |
| HOA Fees | Varies by property |
| Property Management | 8-10% of rent |
Variable Expenses (Budgeted)
| Expense | Typical Range |
|---|---|
| Repairs & Maintenance | 5-10% of rent |
| Capital Expenditures | 5-10% of rent |
| Vacancy Reserve | 5-10% of rent |
Operating Expense Ratio
Operating Expenses ÷ Gross Income = Operating Expense Ratio
- 35-45%: Excellent efficiency
- 45-55%: Average
- 55%+: Review for issues
Example Analysis
Property Details
- Purchase Price: $200,000
- Down Payment: $40,000 (20%)
- Loan: $160,000 at 7%, 30 years
- Monthly P&I: $1,064
Income
| Item | Monthly |
|---|---|
| Gross Rent | $1,800 |
| Less: Vacancy (5%) | -$90 |
| Pet Rent | $50 |
| Effective Gross Income | $1,760 |
Expenses
| Item | Monthly |
|---|---|
| Property Taxes | $208 |
| Insurance | $100 |
| Property Management (10%) | $180 |
| Repairs Reserve (5%) | $90 |
| CapEx Reserve (5%) | $90 |
| Lawn/Snow | $50 |
| Total Operating Expenses | $718 |
Net Operating Income (NOI)
$1,760 - $718 = $1,042
Cash Flow
$1,042 - $1,064 (mortgage) = -$22/month
Analysis
This property has slightly negative cash flow. Options:
- Negotiate lower price
- Find ways to increase rent
- Reduce expenses (self-manage)
- Accept for appreciation potential
Optimization Strategies
Increase Income
- Market rent analysis (are you under-rented?)
- Add amenities (washer/dryer, smart locks)
- Pet-friendly policy
- Reduce vacancy with better marketing
Decrease Expenses
- Self-manage if local
- Shop insurance annually
- Preventive maintenance
- Energy efficiency improvements
Improve Financing
- Refinance when rates drop
- Pay down principal to remove PMI
- Consider 15-year for lower rate (if cash flow allows)
Key Metrics to Track
Cash-on-Cash Return
Annual Cash Flow ÷ Total Cash Invested × 100
Example: $2,400 annual cash flow ÷ $50,000 invested = 4.8% CoC return
Cap Rate
NOI ÷ Purchase Price × 100
Example: $12,504 NOI ÷ $200,000 = 6.25% cap rate
Break-Even Ratio
(Operating Expenses + Debt Service) ÷ Gross Income
Under 85% = healthy cushion for vacancy
Conclusion
Cash flow analysis separates successful investors from those who lose money. Run the numbers before buying, monitor monthly, and adjust your strategy as needed. Use our Cash Flow Tracker spreadsheet to automate these calculations.
Frequently Asked Questions
What is good cash flow for a rental property?
A good rule of thumb is $100-200+ per unit per month after all expenses. In expensive markets, breaking even or slightly positive may be acceptable if you're banking on appreciation.
Should I include mortgage principal in cash flow?
No. Cash flow is about actual money in and out. Principal paydown is forced savings/equity building, but it doesn't affect your monthly cash available.
What vacancy rate should I use?
5-8% for single-family in stable markets. 10%+ for multi-family or higher turnover areas. Check local market data for realistic estimates.
How do I account for repairs and CapEx?
Budget 5-10% of rent for repairs (minor fixes) and 5-10% for CapEx (major replacements like roof, HVAC). Total 10-20% reserved for maintenance.