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1Scan for outdated or missing drivers - takes under a minute2Repair Windows errors before they cause bigger problems3Fix the driver behind crashes, sound loss and screen glitchesCalculate all three rental-property metrics from the same 12-month income and expense assumptions. First subtract vacancy and collection losses from potential rent and other income to find effective gross income; subtract operating expenses to get net operating income (NOI). Divide NOI by the purchase price for the cap rate. For cash flow, subtract annual debt service and clearly identified reserves or capital spending from NOI. Divide that cash flow by the cash you actually invested to get cash-on-cash return. These are pre-income-tax underwriting measures: cap rate describes the property before the buyer’s financing, while cash flow and cash-on-cash return reflect it.
What each rental-property metric tells you
Cash flow, cap rate, and cash-on-cash return answer related but different questions. Calculate them from consistent annual assumptions, then use each for its intended purpose rather than treating any one as a complete measure of investment performance.
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| Metric | Formula | What it measures | Includes financing? |
|---|---|---|---|
| Net operating income (NOI) | Effective gross income − operating expenses | Property income remaining before debt payments, income taxes, and investor-specific costs | No |
| Cap rate | Annual NOI ÷ property value | NOI relative to the property’s price or stated value | No |
| Annual cash flow | NOI − debt service − any stated reserves or capital expenditures | Cash remaining after the costs included in the chosen convention | Yes |
| Cash-on-cash return | Annual cash flow ÷ initial cash invested | Annual cash flow relative to the investor’s stated cash contribution | Yes |
The National Apartment Association’s June 2017 quick guide uses cash flow as NOI minus debt service, capital expenditures, and replacement reserves, and defines cash-on-cash return as cash flow divided by the down payment or initial equity. Those are useful conventions, not regulatory standards. This guide shows both the simple cash-flow version and a version that subtracts reserves and capital spending so you can see which one you are using.
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Use a single annual period for rent, vacancy, operating costs, debt service, reserves, and the resulting return calculations. If you have monthly figures, annualize each recurring amount consistently; do not compare annual NOI with one month of debt payments. For a property you do not own yet, use documented leases and current local information where possible, and label estimates as estimates. The Federal Reserve describes direct income capitalization using stabilized annual NOI; a projection based on a different or unstabilized period should not be presented as though it were stabilized.
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Separate the property’s operating performance from the buyer’s financing and personal tax position. For the operating calculation, include expenses that apply to running the rental. For the financing calculation, subtract loan payments after NOI. For cash-on-cash, specify what acquisition cash is included in the denominator. Keep income-tax effects outside these pre-tax figures unless you build a separately labeled after-tax analysis using appropriate tax assumptions.
How to calculate effective gross income
Effective gross income (EGI) is the income available after accounting for vacancy and collection loss. The NAA guide describes EGI as gross potential rent less vacancy, plus tenant reimbursement revenue and other income. Organize the income lines before estimating expenses.
- Estimate potential scheduled rent. Add the rent the units would generate over 12 months if occupied and paying according to the assumptions you specify. Use the actual lease terms for an existing rental or a defensible local rent estimate for a prospective one; do not silently treat asking rent as collected rent.
- Add other property income. Include recurring income attributable to the property, such as tenant reimbursements or other charges you expect to collect. Do not count a reimbursement as both income and an expense reduction: record it consistently on one side of the calculation or show both lines.
- Subtract vacancy and collection loss. Estimate rent that may not be received because of vacant units, turnover, or nonpayment. Show the dollar assumption and its basis. There is no universal vacancy percentage established by the cited sources, so do not treat a generic percentage as a local market rule.
The result is EGI:
EGI = potential scheduled rent + other property income − vacancy and collection loss
Vacancy belongs in the underwriting revenue estimate even though the tax treatment is different: the IRS says an owner generally cannot deduct the loss of rental income from vacancy. That tax rule does not make the vacant period economically costless or justify assuming full rent will be collected.
How to calculate NOI
Subtract operating expenses from EGI to calculate NOI:
NOI = EGI − operating expenses
NOI is the bridge between revenue assumptions and the property-level cap rate. It is calculated before debt service, investor income taxes, and acquisition-specific cash contributions. List the expenses that actually apply to the property rather than using an unexplained single expense allowance.
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Operating expenses to consider
- Property taxes and insurance.
- Utilities the owner pays, if any.
- Management fees, if the property is professionally managed or if your underwriting explicitly budgets for management.
- Routine maintenance and repairs.
- Other recurring operating costs that apply to the property, such as applicable services or tenant-related costs.
Use annual amounts on each line, and distinguish routine operating costs from large capital work. A major replacement or improvement may belong in a capital-expenditure or reserve line in the cash-flow calculation rather than being folded into routine repairs. The sources do not establish a universal maintenance or expense percentage; property condition, local costs, insurance, utilities, and the rental arrangement matter.
Keep tax net income separate from underwriting NOI
IRS Publication 527 (2025) discusses deductible rental expenses including maintenance, insurance, taxes, mortgage interest, management fees, repairs, and utilities, and it treats depreciation as a capital expense recovered over the property’s expected life. Those tax categories are not a replacement formula for underwriting NOI. In particular, mortgage interest belongs to the tax analysis, while loan payments are addressed after NOI in the cash-flow calculation. Depreciation is not a cash payment in the annual operating ledger, so do not subtract it as though it were an operating cash expense when calculating this NOI convention.
For mixed personal and rental use, the IRS says shared expenses must be reasonably divided. A duplex owner who lives in one part, for example, may need to allocate shared interest and taxes. The rental calculation should use only the portion attributable to the rental activity when that distinction applies.
How to calculate cap rate on a rental property
For a purchase screening calculation, divide annual NOI by the purchase price, then multiply by 100 to express the result as a percentage:
Cap rate = annual NOI ÷ purchase price × 100
If you are evaluating an owned property at a current estimated value rather than its original purchase price, label that denominator as current property value. Do not switch between purchase price and market value without saying so; the result answers a different comparison question.
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The cap rate is property-level: it does not subtract the buyer’s mortgage payment. The Federal Reserve’s supervisory guidance describes direct income capitalization as dividing estimated stabilized annual income by a cap-rate factor. It also explains that the method assumes the income or rate captures relevant risk and income characteristics. That is a valuation framework, not a guarantee that a particular cap rate predicts appreciation, total return, or safety.
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Use stabilized income and comparable evidence
A cap rate built from unusually low or high income can mislead. Federal Reserve guidance cautions that direct capitalization is not appropriate for troubled real estate when income is not at normal or stabilized levels; a stabilization period may need to be considered. If a unit is vacant during renovation or rents are temporarily disrupted, identify the current figures and any stabilized projection separately rather than blending them.
When comparing rates, compare like with like. The Federal Reserve identifies property type, market area, financing differences, rental arrangements, tenant improvements, location, and building characteristics as relevant considerations in analyzing comparable rates. A single market-wide target is not established by these sources. Local comparable evidence and the property’s own risks are more useful than an unsupported rule of thumb.
How to calculate rental property cash flow
Cash flow adds the buyer’s financing and selected cash outlays to the NOI calculation. A simple pre-tax measure is:
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For a fuller cash-flow convention, the NAA guide’s 2017 formula is:
Annual cash flow = NOI − annual debt service − capital expenditures − replacement reserves
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State which version you use. Debt service is the annual loan-payment amount used in your analysis; keep property taxes, insurance, and other operating costs in the NOI expense lines rather than subtracting them again below NOI. If you budget capital work or replacement reserves, show those lines separately so a reader can tell whether the reported cash flow is before or after those amounts.
Distinguish actual spending from reserve assumptions
Capital expenditures are cash costs for larger work or replacements rather than ordinary recurring operation. A replacement reserve is an amount set aside in the analysis for future needs. A reserve allocation may reduce the cash flow figure even if the money was not spent during that particular year. Identify whether the figure represents cash actually paid or a planned reserve so that comparisons are meaningful.
Do not subtract a cost twice. If a repair is already included among operating expenses in NOI, do not include it again as capital spending below NOI. Conversely, excluding a major replacement from routine expenses does not mean the ownership economics have no exposure to it; you may account for it explicitly in the capital or reserve lines.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Cash-on-cash return formula and denominator
Calculate cash-on-cash return by dividing the annual cash flow you selected by the initial cash invested:
Cash-on-cash return = annual cash flow ÷ initial cash invested × 100
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A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11The NAA guide uses down payment or initial equity for the denominator. For a transparent buyer-to-buyer comparison, define your denominator more precisely. You might report the guide’s narrower down-payment convention and separately state a broader all-in acquisition-cash convention that includes cash closing costs and upfront repairs. Do not include borrowed funds as though they were the investor’s cash contribution, and do not omit material acquisition spending without labeling the choice.
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The numerator and denominator must refer to compatible assumptions. If your cash-flow numerator subtracts annual reserves and capital costs, state that; if it is before those costs, state that instead. The resulting percentage is an annual pre-tax cash yield on the cash amount you chose, not a measure of the property’s entire return over time.
Worked example: calculate all four figures from the same assumptions
The following is a hypothetical illustration only. None of the inputs is a market statistic or suggested benchmark. It uses one 12-month period and makes the cost and cash-invested assumptions explicit.
| Input | Hypothetical annual amount | Calculation note |
|---|---|---|
| Potential scheduled rent | $30,000 | Assumed for illustration |
| Other property income | $1,200 | Assumed for illustration |
| Vacancy and collection loss | $1,560 | Assumed loss; not a market-rate claim |
| Property taxes | $4,200 | Operating expense assumption |
| Insurance | $1,500 | Operating expense assumption |
| Owner-paid utilities | $1,200 | Operating expense assumption |
| Management | $2,400 | Operating expense assumption |
| Routine maintenance and repairs | $1,800 | Operating expense assumption |
| Other operating costs | $600 | Operating expense assumption |
| Purchase price | $250,000 | Cap-rate denominator |
| Annual debt service | $12,000 | Financing assumption |
| Capital expenditures | $1,500 | Included below NOI |
| Replacement reserve | $1,000 | Included below NOI |
| Cash invested | $60,000 | $50,000 down payment, $6,000 closing costs, and $4,000 upfront repairs |
- Potential gross income: $30,000 rent + $1,200 other income = $31,200.
- Effective gross income: $31,200 − $1,560 vacancy and collection loss = $29,640.
- Operating expenses: $4,200 + $1,500 + $1,200 + $2,400 + $1,800 + $600 = $11,700.
- NOI: $29,640 − $11,700 = $17,940.
- Cap rate: $17,940 ÷ $250,000 = 0.07176, or about 7.18%.
- Annual cash flow after debt service, capital expenditures, and replacement reserve: $17,940 − $12,000 − $1,500 − $1,000 = $3,440.
- Cash-on-cash return: $3,440 ÷ $60,000 = 0.0573, or about 5.73%.
The example’s 7.18% cap rate and 5.73% cash-on-cash return differ because the first compares NOI with the property price and the second compares post-financing, post-reserve cash flow with the investor’s specified cash contribution. If the assumed loan terms changed while the property income, expenses, and price stayed fixed, cash flow and cash-on-cash return would change; cap rate would not.
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Common calculation errors to avoid
- Using gross rent as NOI: subtract vacancy and collection loss, then operating expenses before calculating NOI.
- Subtracting mortgage payments in NOI: cap rate is calculated from NOI before financing; debt service belongs in cash flow.
- Mixing periods: use matching annual inputs throughout, or clearly annualize monthly figures.
- Hiding the cash-flow convention: say whether reserves and capital expenditures have been subtracted.
- Using an unclear denominator: identify purchase price or current value for cap rate, and specify what acquisition cash is included for cash-on-cash return.
- Counting costs twice: keep each expense in one place, especially repairs, reimbursements, and capital work.
- Using tax deductions as operating cash expenses: keep mortgage interest and depreciation in the tax analysis rather than treating the tax return as the NOI calculation.
- Treating a calculated percentage as a forecast: the metric is only as reliable as its rent, vacancy, expense, financing, value, and reserve assumptions.
What these return measures do not tell you
Cap rate does not include loan structure, and cash-on-cash return does not include every component of investment performance. Neither formula, by itself, measures future appreciation, eventual sale proceeds, total return across a holding period, or the probability of loss. The calculation also cannot make an unstabilized rent assumption reliable merely by converting it to a percentage.
For a meaningful screen, preserve the assumptions alongside the outputs: the 12-month rent basis, vacancy and collection loss, itemized operating expenses, purchase price or valuation basis, debt service, capital or reserve treatment, and cash denominator. Compare properties only when those inputs and conventions are sufficiently alike. Local rents, taxes, insurance, expenses, financing, and applicable rules vary by location and property.
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