CapEx Calculator
Calculate rental property capital expenditures (CapEx) and vacancy sinking funds to protect your net cash flow against major component breakdowns.
1. Rental Revenue & Vacancy Assumptions
$
Scheduled monthly rental income across all units
%
Market vacancy buffer (typically 5%–8% or ~1 month/yr)
$
Paint, lock re-keying, professional cleaning, marketing
Yrs
Typical lease duration before tenant turnover (default 2 yrs)
2. Major Structural Components (CapEx Sinking Fund)
Enter the replacement cost and estimated remaining useful life for each major physical system.
🏠 Roof & Gutters
Asphalt shingle / tile roof replacement
$
Yrs
—
Mid-Term
❄️ HVAC & Furnace
Central air conditioner, heat pump, or furnace
$
Yrs
—
Mid-Term
🚿 Water Heater
Tanked or tankless water heating unit
$
Yrs
—
Mid-Term
🍳 Kitchen Appliances
Refrigerator, stove/range, dishwasher
$
Yrs
—
Mid-Term
🪵 Flooring & Carpet
LVP, hardwood, tile, or carpeting
$
Yrs
—
Long-Term
🎨 Exterior Siding & Paint
Exterior repaint, trim, deck sealing
$
Yrs
—
Long-Term
⚡ Plumbing & Electrical
Sewer line, main panel, supply repipe
$
Yrs
—
Long-Term
Recommended Monthly Total Reserve Fund
$0.00
Balanced Reserve Buffer
Monthly CapEx Sinking Fund
$0.00
$0.00 / year
Monthly Vacancy & Turnover
$0.00
$0.00 / year
Total Reserve % of Gross Rent
0.0%
Target: 12%–20% of rent
Target 6-Month Emergency Cushion
$0.00
Liquid cash reserves in bank
Component Sinking Fund Schedule
| Component | Replacement Cost | Remaining Life | Monthly Sinking | Annual Sinking | Urgency |
|---|
How to Use This Calculator
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1
Select Calculation Mode & Currency: Choose between the Component Sinking Fund mode (for an itemized, bottom-up audit of your specific building's systems) or the Rule-of-Thumb Screener mode (for rapid property deal screening before making an offer).
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2
Input Rental Income & Vacancy Metrics: Enter your scheduled gross monthly rent, expected market vacancy rate (typically 5% to 8%), and average tenant turnover costs (make-ready expenses like repainting and lock changes).
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3
Adjust Component Lifespans or Rule Percentages: In itemized mode, refine the estimated replacement cost and remaining useful lifespan in years for major assets (roof, HVAC, water heater, appliances, flooring). In rule mode, select your preferred CapEx percentage (5% to 10%) or enter a flat dollar-per-door rate.
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4
Review Your Monthly Sinking Allocation: Examine the recommended monthly reserve transfer amount, review the visual revenue distribution bar, and check the 6-month liquid cash emergency target for your bank account.
The Formula
Capital expenditures occur intermittently in large, lumpy lump-sums, but disciplined investors smooth these expenses into consistent monthly sinking fund transfers. The mathematics behind component-based sinking fund budgeting divides the total replacement cost by the component's remaining operational lifespan in months:
Monthly CapEx Reserve (Component i) = Replacement Cost_i / (Remaining Years_i × 12)
Total Monthly CapEx = Σ Monthly CapEx Reserve_i
Monthly Vacancy & Turnover = (Gross Monthly Rent × Vacancy %) + (Turnover Cost / (Tenancy Years × 12))
Total Monthly Sinking Fund = Total Monthly CapEx + Monthly Vacancy & Turnover
Where each variable represents:
- Replacement Cost_i: The fully installed, current contractor estimate to replace the specific mechanical or structural component.
- Remaining Years_i: The estimated number of useful operational years before failure or mandatory replacement.
- Gross Monthly Rent: Total scheduled gross lease revenue collected before any debt service or operational deductions.
- Vacancy %: The expected percentage of time the property sits vacant between tenants or uncollected due to default.
- Turnover Cost: Direct out-of-pocket costs incurred during tenant transitions (cleaning, patching, re-keying, administrative listing fees).
Example
Consider a single-family rental property generating $2,400 per month in gross scheduled rent. The investor models a 5% vacancy rate ($120.00/month) and assumes tenant turnover costs $600.00 every 2 years (24 months), which equals $25.00/month. The combined monthly vacancy and turnover reserve is $145.00/month ($1,740.00/year).
Next, the investor audits 7 core property components:
- Roof: $12,000 cost ÷ (10 years × 12) = $100.00 / month ($1,200.00 / year)
- HVAC System: $6,000 cost ÷ (6 years × 12) = $83.33 / month ($1,000.00 / year)
- Water Heater: $1,440 cost ÷ (4 years × 12) = $30.00 / month ($360.00 / year)
- Kitchen Appliances: $2,880 cost ÷ (4 years × 12) = $60.00 / month ($720.00 / year)
- Flooring & Carpet: $4,200 cost ÷ (7 years × 12) = $50.00 / month ($600.00 / year)
- Exterior Siding & Paint: $7,200 cost ÷ (12 years × 12) = $50.00 / month ($600.00 / year)
- Plumbing & Electrical: $2,400 cost ÷ (10 years × 12) = $20.00 / month ($240.00 / year)
Sum of Monthly CapEx Reserves: $100.00 + $83.33 + $30.00 + $60.00 + $50.00 + $50.00 + $20.00 = $393.33 / month ($4,720.00 / year).
Total Recommended Monthly Sinking Fund: $393.33 (CapEx) + $145.00 (Vacancy/Turnover) = $538.33 / month ($6,460.00 / year), representing 22.43% of gross rent. To remain fully solvent against unexpected concurrent repairs, the recommended 6-month liquid operating cushion in the property's escrow account is $3,230.00.
Frequently Asked Questions
What is a typical CapEx reserve for a rental property?
Most experienced real estate investors allocate between 5% and 10% of gross monthly rental income strictly for Capital Expenditures (CapEx), or a flat rule-of-thumb of $150 to $250 per month per unit. For older properties built prior to 1980 with aging mechanical systems, reserves often increase to 12% to 15% until major capital items are replaced.
What is the difference between CapEx and routine maintenance (OpEx)?
Routine maintenance covers ongoing operating expenses that maintain the property in its current operational state, such as clearing clogged drains, patching drywall, servicing furnaces, or repairing door locks. CapEx covers large-scale capital replacements that extend the asset's structural lifespan, such as replacing a roof, installing a new HVAC system, or repaving a driveway. Tax-wise, routine repairs are deducted in the current tax year, whereas CapEx must be capitalized and depreciated over 27.5 residential years.
How do you calculate a sinking fund for capital expenditures?
To calculate a component-based sinking fund, estimate the total replacement cost of each major physical asset and divide that cost by its remaining useful lifespan in months (Monthly Reserve = Estimated Replacement Cost / (Remaining Years x 12)). Summing this requirement across the roof, HVAC, water heater, appliances, flooring, siding, and plumbing yields the precise monthly reserve needed.
How much should landlords budget for vacancy rate and tenant turnover?
Industry standards recommend budgeting 5% to 8% of gross scheduled rent for vacancy in stable residential markets, which accounts for roughly 2.5 to 4 weeks of uncollected rent each year. In addition to lost rent, landlords should budget $500 to $1,000 per tenant turnover to cover professional cleaning, touch-up painting, re-keying locks, and leasing marketing amortized over the expected 2-to-3 year tenant stay.
How large should an emergency cash reserve cushion be for rental properties?
Prudent real estate investors maintain a liquid emergency cash reserve of 3 to 6 months of total property carrying costs (mortgage principal and interest, property taxes, hazard insurance, and routine utilities) per rental unit. This liquid buffer prevents forced personal debt or foreclosure during extended tenant vacancies or catastrophic unexpected repairs.