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House Hacking Calculator

Buy a multi-unit property, live in one unit, rent the rest. See how rental income offsets your mortgage and accelerates financial independence.

Property Details
$
%
= $12,250
%
Rental Income
$
Total rental income: $1,200/mo (1 unit rented)
%
Monthly Expenses
$
$
% of price/yr
$
Your Effective Housing Cost
$0/mo
vs renting at $0/mo — you save $0
Monthly Breakdown
Mortgage (P&I)
$0
Tax + Insurance
$0
Maintenance + HOA
$0
PMI
$0
Total Monthly Cost
$0
Rental Income (net vacancy)
$0
Key Metrics
Net Housing Cost
$0/mo
Cost Offset
0%
Cash-on-Cash Return
0%
Annual Cash Flow
$0
Total Cash Invested
$0
Cap Rate
0%
Cost Breakdown
Compare Property Types Side by Side

Using your current inputs, see how duplex, triplex, and fourplex compare for house hacking returns.

Duplex
1 unit rented
Monthly Mortgage--
Total Monthly Cost--
Rental Income--
Net Housing Cost--
Cost Offset--
Cash-on-Cash--
Annual Cash Flow--
Triplex
2 units rented
Monthly Mortgage--
Total Monthly Cost--
Rental Income--
Net Housing Cost--
Cost Offset--
Cash-on-Cash--
Annual Cash Flow--
Fourplex
3 units rented
Monthly Mortgage--
Total Monthly Cost--
Rental Income--
Net Housing Cost--
Cost Offset--
Cash-on-Cash--
Annual Cash Flow--
Visual Comparison
FIRE Impact Analysis

See how house hacking reduces your FIRE number by lowering housing expenses. Every $1/mo saved on housing = $300 less needed in your FIRE portfolio (4% SWR).

$
$
%
Renting (Current)
Annual Housing Cost $0
Total Annual Expenses $0
FIRE Number $0
House Hacking
Annual Housing Cost $0
Total Annual Expenses $0
FIRE Number $0
Impact Summary
Monthly Savings
$0
Annual Savings
$0
FIRE Number Reduction
$0
FIRE Number Comparison
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How to Use This Calculator

1

Enter Property Details

Select your property type (duplex, triplex, or fourplex), enter the purchase price, down payment percentage, interest rate, and loan term.

2

Set Rental Income & Expenses

Enter the expected rent per unit, vacancy rate, property taxes, insurance, maintenance percentage, and HOA if applicable.

3

Review Your Results

See your net housing cost, cost offset percentage, cash-on-cash return, and FIRE impact. Compare duplex vs triplex vs fourplex in the Scenario tab.

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Formula & Methodology

Monthly Mortgage Payment

M = P × [r(1+r)^n] / [(1+r)^n − 1]

Where P = loan amount, r = monthly interest rate, n = total number of payments.

Net Housing Cost

Net Cost = Total Monthly Expenses − Rental Income × (1 − Vacancy Rate)

Your effective housing cost after rental income offsets your mortgage and expenses.

Cash-on-Cash Return

CoC = Annual Cash Flow / Total Cash Invested × 100%

Measures the return on your actual out-of-pocket investment including down payment and closing costs.

FIRE Number

FIRE Number = Annual Expenses / Safe Withdrawal Rate

The portfolio size needed to cover your expenses indefinitely. Lower housing costs = lower FIRE number.

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Key Terms Explained

House Hacking Buying a multi-unit property, living in one unit, and renting out the others to offset or eliminate your housing costs.
FHA Loan A government-backed mortgage requiring as little as 3.5% down on 1-4 unit owner-occupied properties.
Cash-on-Cash Return Annual cash flow divided by total cash invested. Measures the return on your actual out-of-pocket money.
PMI Private Mortgage Insurance required when the down payment is below 20%, typically 0.5-1% of the loan balance per year.
FIRE Number The investment portfolio needed to cover annual expenses indefinitely, calculated as Annual Expenses / Safe Withdrawal Rate.
Cost Offset The percentage of your total housing costs covered by rental income from tenants.
Cap Rate Net Operating Income / Purchase Price. Shows the property's return as if purchased with all cash.
Vacancy Rate The percentage of time rental units sit empty. Budget 5-8% for residential properties.
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Real-World Examples

👤 Alex

Duplex House Hack with FHA Loan

Inputs: Purchase: $300,000, Down: 3.5% ($10,500), Rate: 6.75%, Rent: $1,400/mo from one unit

Result: Result: Total cost $2,600/mo, rental income $1,330/mo (after vacancy). Net housing cost = $1,270/mo, a 51% offset vs paying a full mortgage alone.

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The House Hacking Strategy

Why House Hacking Works

Housing is typically the largest monthly expense. House hacking attacks this directly by having tenants pay a portion of your mortgage. With FHA financing at 3.5% down, you can control a multi-unit property with far less capital than traditional investment property financing (which requires 20-25% down).

Choosing the Right Property Type

Duplexes are the simplest entry point with just one tenant to manage. Triplexes and fourplexes generate more rental income but cost more upfront and require more management. All three qualify for FHA and conventional owner-occupied financing as long as you live in one unit.

The FIRE Accelerator Effect

House hacking has a compounding effect on financial independence. Every dollar saved on housing reduces your annual spending, which in turn reduces the FIRE portfolio you need to accumulate. At a 4% safe withdrawal rate, saving $500/month on housing means you need $150,000 less in your retirement portfolio.

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Frequently Asked Questions

Basics What is house hacking?
House hacking means buying a multi-unit property (duplex, triplex, or fourplex), living in one unit, and renting out the others. The rental income offsets your mortgage payment, often reducing your effective housing cost to near zero or even generating positive cash flow.
Basics Can I use an FHA loan for house hacking?
Yes. FHA loans allow as little as 3.5% down on 1-4 unit properties as long as you occupy one unit as your primary residence. This is one of the biggest advantages of house hacking over traditional rental investing, which typically requires 20-25% down.
Basics How does house hacking affect my FIRE number?
House hacking reduces your housing expense, which lowers your total annual spending. Since the FIRE number = Annual Expenses / Safe Withdrawal Rate, every dollar saved on housing reduces the portfolio you need by $25 (at a 4% SWR). Saving $1,000/month reduces your FIRE number by $300,000.
Strategy Is a duplex or fourplex better for house hacking?
A fourplex generates more rental income to offset your mortgage, but costs more upfront and involves managing three tenants instead of one. Duplexes are simpler and more affordable. The best choice depends on your budget, risk tolerance, and local market conditions.