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Buy vs. Rent Financial Simulator

Compare capital allocation strategies over time

Should you buy a home or rent and invest the difference? This simulator models two financial strategies side-by-side so you can compare outcomes with your own numbers.

The Two Strategies

Buy

Purchase property with a mortgage. Your asset is the home value; outflows include mortgage payments, taxes, insurance, and maintenance.

Rent + Invest

Rent and invest what buying would have cost: the down payment and closing costs up front, plus the monthly difference whenever renting is cheaper.

How sure is this?

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Monte Carlo Simulation

Nobody can predict 30 years of returns. The How sure is this? section runs hundreds of simulations with randomized year-by-year returns to show how often buying wins and the range of possible outcomes.

Tip: Adjust parameters in the input panel and watch the charts update. On small screens it collapses to the Inputs drawer. The Net Value chart is the key decision metric. For a probabilistic view, try the How sure is this? section.

How this works

▸The two strategies

Buy

You purchase property with a mortgage. Your asset is the home value. Outflows include the down payment, closing costs, monthly mortgage payments, property levy, insurance, and maintenance.

Rent + Invest

Rent and invest what buying would have cost: the down payment and closing costs up front, plus the monthly difference whenever renting is cheaper.

▸Net Value

A home appreciating in value looks great — but you're also paying mortgage interest, property levy, insurance, and maintenance. Net Value captures the full picture:

Net Value = Asset Value − Total Outflows

This tells you which strategy actually leaves you wealthier. A scenario can have higher asset growth but lower net value if the costs are steep enough.

▸Breakeven

The breakeven point is the year when buying overtakes renting + investing in net value. Before this point, the renter is wealthier. After it, the buyer pulls ahead.

No breakeven? That means one strategy dominates for the entire simulation period. If you're planning to sell before the breakeven year, the dominant strategy may flip.

▸Monte Carlo confidence

The main charts assume growth rates play out exactly as configured. But nobody can predict 30 years of returns. The How sure is this? section runs hundreds of simulations where property appreciation, equity growth, and rent inflation vary randomly each year using bell-curve distributions centered on your inputs.

Instead of “Buy wins by $142K,” you see: “Buying wins in 68% of simulations.” The fan chart shows the range of possible outcomes, and the tornado chart reveals which parameters matter most.

🏠 Rent or buy? decision tool by palsagar ★ GitHub

Region Outlook

Your situation

Outlook assumptions

updating…

Buy net value

Rent net value

Buy cost · yr 1

Rent cost · yr 1

Net value over time

What you'd walk away with, minus everything you put in — at every year.

How sure is this?

500 simulated futures of the Buy − Rent difference. Bands: 50% and 90% of outcomes.

Which assumption to stress-test hardest

Wider bar = bigger swing in the outcome. Blue = assumption goes up, grey = goes down. Each assumption is moved by a realistic amount — for the growth and inflation rates, that amount shrinks as your horizon lengthens. Hover a bar to see its before and after.

Where the money goes

Cumulative cash out of pocket on each side.

Cost of ownership breakdown

The numbers

🔒 Privacy: This app does not track any user data, use cookies, or perform any analytics. Self-hosted on a tiny VPS via Coolify.
Calculations use monthly granularity; Net Value prices a full exit at every year (selling costs and capital-gains tax on both sides). Tax defaults follow the selected region. Source: GitHub.

Advanced

Defaults follow the selected region.