Why Your "Cash-on-Cash" Calculation Is Lying to You

TL;DR

• Most rental "12% cash-on-cash" numbers ignore vacancy, CapEx, maintenance, and property management — sometimes all four.
• Real cash on cash return on the same property is often 4–6% after honest reserves.
• The four missing reserves typically take 20–30% of gross rent off the top.
• If you are self-managing, still deduct PM — because your time is not free, and one day you will hire it out.

Scroll any real estate Instagram and you will see "this rental cash-flows 12.8% cash-on-cash." Nine times out of ten, that number is calculated as (rent − PITI) / down payment and nothing else. That is not cash-on-cash return. That is marketing. Real landlords run the number with four additional line items that eat 20–30% of gross rent before you see a dollar. This article shows you the full math.

What cash-on-cash actually measures

CoC = Annual pre-tax cash flow / Cash invested

"Annual pre-tax cash flow" = gross rent − ALL operating expenses − debt service. "Cash invested" = down payment + closing + rehab + reserves you left in the deal.

The mistake is in what "all operating expenses" includes. Most newbie calculators treat it as just PITI + maybe repairs. Real investors add four more:

1. Vacancy
2. CapEx (capital expenditure reserves)
3. Maintenance (recurring)
4. Property management

The four missing line items

1. Vacancy — 5–10% of gross rent

Every unit is vacant between tenants. Market-dependent:

• Hot rental markets (Tampa, Phoenix, Charlotte): 5–7 days avg between tenants → ~5% vacancy
• Average markets: 3–4 weeks → ~7% vacancy
• Slow/declining markets: 6–10 weeks → ~10% vacancy

Use at least 8% unless you have data proving otherwise.

2. CapEx — 8–12% of gross rent

CapEx is not maintenance. CapEx is the big-ticket replacements that happen every 10–30 years but average out monthly:

On $1,850 rent, that is 27%. Most calculators use 10%. Reality is property-specific — old roofs, dated kitchens, unknown HVAC age mean higher CapEx now.

3. Maintenance — 5–8% of gross rent

Recurring repairs: a broken faucet, a stuck garage door, a clogged drain, annual HVAC servicing. Not CapEx. Budget 6% of gross rent as a solid default.

4. Property management — 8–10% of rent + fees

Even if you self-manage, bake it in. Two reasons:

1. You will eventually hire a PM or want the option to sell as a turnkey.
2. Your time has opportunity cost — you should be compounding, not chasing lightbulbs.

Typical PM cost:

• Monthly fee: 8–10% of rent collected
• Leasing fee: 50–100% of one month's rent (every tenant turnover)
• Renewal fee: $150–300 per renewal

Realistic total load: 10–12% of gross rent when amortized.

Worked example: $250K rental, $1,850 rent

Ingredients:

• Purchase: $250,000
• Down payment (25%): $62,500
• Closing + reserves: $7,500
• Loan: $187,500 @ 7.25% 30yr = $1,279 P&I
• Taxes: $275/month
• Insurance: $95/month
• PITI: $1,649

Newbie math:

• Rent − PITI: $1,850 − $1,649 = $201/month → $2,412/year
• CoC: $2,412 / $70,000 = 3.4%

Wait, that is already bad before reserves? Yes. Many "BRRRR deals" in 2026 do not cash-flow at these rates, full stop.

But let's assume rent was $2,300 (better market):

• Rent − PITI: $2,300 − $1,649 = $651/month
• Newbie CoC: $7,812 / $70,000 = 11.2% 🎉

Now subtract the four reserves:

• Vacancy (8%): $184
• CapEx (10%): $230
• Maintenance (6%): $138
• PM (10%): $230
• Total reserves: $782/month

Real cash flow: $651 − $782 = −$131/month. You are losing $1,572/year. Real CoC: −2.2%.

That is not a bug — that is 2026. Many properties that "look great" on newbie math bleed cash once reserves are real.

When reserves can be lower

There are cases where you can honestly lower some line items:

• Brand-new build: CapEx accrual can be 5–7% for the first 8 years.
• Full rehab at purchase: CapEx can be 6–8% for 5 years if you did roof, HVAC, windows, kitchen.
• Self-managing with 4+ doors and good tenants: PM accrual can be 5–7% if you have the bandwidth.
• Class-A neighborhood with professional tenants: Vacancy can be 4–5%.

But you need to justify every reduction with data, not hope.

The 1% rule as a sanity check

The old "1% rule" (monthly rent ≥ 1% of purchase price) was a heuristic for whether a rental would cash flow after real reserves. In 2026 with rates at 7%+, you often need 1.1–1.2% to cash-flow honestly. Anything under 0.8% is appreciation-only — you are betting on the market, not the property.

Where this connects

Cash-on-cash is not your only metric, but getting it right keeps you out of the rental properties that look like winners and bleed cash. Once you have a honest CoC, evaluate the asset over time using IRR and equity multiple — see Passive Real Estate: IRR, Equity Multiple, and Preferred Return Decoded. For the BRRRR math that depends on all of this being accurate, see BRRRR vs Fix & Flip.

Run honest numbers before you close

Vricko's ROI Calculator bakes in all four reserves by default and lets you adjust each one with reasoning. It shows both "newbie math" and "realistic math" side by side, so you see what you are doing when you lower a number — and whether the deal still works after you do. No more 12% cash-on-cash numbers that turn into 2%.

Run your rental through the ROI Calculator — honest math before you sign the contract.