Calculator Inputs
Enter your monthly and annual property assumptions below. Use the same currency for every amount.
Example Data Table
This example shows how the monthly cash flow structure can look across sample months using one consistent property scenario.
| Month | Gross Income | Vacancy + Credit Loss | Operating Expenses | Debt Service | Net Cash Flow |
|---|---|---|---|---|---|
| January | $1,925.00 | $114.38 | $733.36 | $950.00 | $127.26 |
| February | $1,925.00 | $114.38 | $733.36 | $950.00 | $127.26 |
| March | $1,925.00 | $114.38 | $733.36 | $950.00 | $127.26 |
Formula Used
Gross Potential Income = Monthly Rent + Other Monthly Income
Vacancy Loss = Gross Potential Income × Vacancy Rate
Credit Loss = (Gross Potential Income − Vacancy Loss) × Bad Debt Rate
Effective Gross Income = Gross Potential Income − Vacancy Loss − Credit Loss
Variable Reserves = Effective Gross Income × Selected Rate
Total Operating Expenses = Fixed Costs + Management + Maintenance + Repairs + CapEx
NOI = Effective Gross Income − Total Operating Expenses
Pre-tax Cash Flow = NOI − Debt Service
Break-even Occupancy = (Operating Expenses + Debt Service) ÷ Gross Potential Income × 100
Cash-on-cash return is calculated as annual cash flow divided by total cash invested. This helps compare rental performance against invested equity.
How to Use This Calculator
- Enter the expected monthly rent and any additional property income.
- Add realistic vacancy and bad debt assumptions instead of perfect occupancy.
- Convert annual taxes and insurance into the form, then add monthly operating costs.
- Use reserve percentages for management, maintenance, repairs, and future capital items.
- Enter loan payments and invested cash to review NOI, cash flow, DSCR, and cash-on-cash return.
Frequently Asked Questions
1. What does monthly rental cash flow mean?
It is the money left after rent losses, operating expenses, reserves, and debt service are subtracted from total monthly rental income.
2. Why should vacancy be included?
Vacancy reflects normal downtime between tenants or periods of underperformance. Ignoring it can make a weak property look better than it really is.
3. What is the difference between NOI and cash flow?
NOI excludes debt payments. Cash flow goes one step further by subtracting mortgage principal, interest, and PMI from NOI.
4. Should reserve items count even if not spent monthly?
Yes. Reserves smooth future maintenance, repairs, and large replacements. They help you judge whether the property truly supports ownership over time.
5. What is a good DSCR?
Many investors and lenders like DSCR above 1.20 or 1.25. Higher values mean the property has more room to absorb stress.
6. Can this calculator work for multi-unit rentals?
Yes. Combine all monthly rent and other income across units, then enter the total operating costs and financing for the property.
7. Why are taxes and insurance entered annually?
These costs are often budgeted or billed annually. The calculator converts them into monthly equivalents for consistent monthly cash flow analysis.
8. Does positive cash flow guarantee a good investment?
No. You should also review appreciation potential, neighborhood risk, capital needs, financing terms, taxes, and your required return.