Rental Property Cash Flow Calculator
Enter NOI, your mortgage payment, rent, and a CapEx reserve percentage below to instantly get real monthly cash flow.
Commonly 5-10% of rent; older properties often warrant more.
What Is Rental Cash Flow?
Rental cash flow is what's realistically left over each year after NOI, your mortgage payment, and a reserve for future capital expenses -- the number that actually predicts whether the property puts money in your pocket or takes it out.
Cash Flow = NOI − Annual Debt Service − Annual CapEx Reserve.
Worked example
$31,200/year NOI, a $2,000/month mortgage payment, $4,000/month rent, and a 7.5% CapEx reserve.
Annual debt service = $2,000 × 12 = $24,000
Annual CapEx reserve = $4,000 × 12 × 7.5% = $3,600
Cash Flow = $31,200 − $24,000 − $3,600 = $3,600 ($300/month)
Common mistake
Treating NOI minus debt service alone as "cash flow" and skipping the CapEx reserve entirely. That real cash still gets spent eventually -- skipping the reserve just means the big repair bill arrives as a surprise instead of a planned expense.
Keep going
- Cash flow starts from NOI; the NOI calculator is where gross income and operating expenses turn into that starting number. NOI Calculator
- Once you know your annual cash flow, dividing it by the cash you actually put in gives cash-on-cash return -- the next step most investors take with this number. Cash-on-Cash Return Calculator
Frequently Asked Questions
Why subtract a CapEx reserve on top of debt service?
NOI already excludes big, irregular capital costs like a new roof or HVAC system -- they're capital expenditures, not operating expenses. A CapEx reserve sets aside real cash now for those real future costs, so "cash flow" doesn't overstate what you can actually spend without leaving the property underfunded when something big breaks.
What percentage of rent should I reserve for CapEx?
Baselane and other rental-property resources commonly cite 5-10% of monthly rent as a simple starting point, with older properties or ones with aging major systems often warranting a higher percentage. It's a planning guideline, not a fixed rule -- a property with a brand-new roof and HVAC can reasonably reserve less.
Is this the same as pre-tax cash flow from the cash-on-cash calculator?
Almost -- the cash-on-cash return calculator's cash flow is NOI minus debt service only. This calculator goes one step further and also subtracts a CapEx reserve, which is a more conservative, realistic number for what you can actually plan to spend.
Can cash flow be negative even with strong NOI?
Yes. A property can have healthy NOI and still show negative cash flow once debt service and a CapEx reserve are both subtracted -- especially with a large loan payment. That's exactly the scenario this calculator is built to catch before you're surprised by it.
Should I use gross or net rent for the CapEx percentage?
This calculator uses monthly rent (gross), which is the standard, simplest basis most rental-property CapEx guidelines are quoted against.
This is a neutral calculation based on the numbers you enter -- not investment advice.
Related Calculators
- NOI Calculator — Income & Cash Flow
- Cap Rate Calculator — Return Metrics
- DSCR Calculator — Financing
- Cash-on-Cash Return Calculator — Return Metrics