How It Works

Each simulated life runs over the chosen time horizon (1–30 years) and compares two paths:

At the end of each simulation, net worth is compared across both scenarios. Results are visualized as interactive dots grouped into three categories: Buying wins (filled indigo dots), Close call (lighter indigo dots), and Renting wins (outlined indigo dots).

Every simulation draws random values from real-world distributions:

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  Home appreciation: Based on Zillow ZHVI data for the selected metro area, adjusted by home type (condos appreciate ~1% less, mobile homes depreciate)
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  Stock market returns:Actual S&P 500 total returns (price + dividends) from randomly selected historical periods — so each simulation might experience market crashes, bull markets, or financial crises
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  Inflation & rent growth: Actual CPI changes from the same historical period — if a simulation hits a high-inflation period, rent and HOA costs spike accordingly
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  Repair shocks: AHS 2023 probabilities adjusted by home age (new homes have 60% lower risk, 50-year-old homes 3x higher) and local labor costs via RS Means city cost indexes (Houston $100/hr labor vs NYC $180/hr). Home type modifiers further adjust for condos, townhomes, and mobile homes.

This randomness creates 100 different futures — some lucky (high appreciation, no major repairs), some unlucky (market downturns, HVAC failure in year 2), and most somewhere in between.

The simulation checks if the monthly payment (PITI + HOA) exceeds 28% of gross income — a common lending guideline. The results page displays a dedicated DTI Guideline section with annual income, the 28% DTI maximum payment, and the estimated payment highlighted in an indigo alert box.

Important:Critical statistics like “198% of the 28% DTI guideline” are bolded for clarity. A favorable simulation outcome doesn't mean the scenario meets lending guidelines — the insights will flag when the payment exceeds typical thresholds.

After seeing the initial results, different scenarios can be explored using the “Adjust Parameters” button. This opens a side drawer to modify:

• •Home price — See how a different price point changes outcomes
• •Annual income — Model a raise or job change
• •Down payment — Test different savings scenarios
• •Monthly surplus — Adjust budget assumptions
• •Mortgage rate — See how rate changes affect outcomes
• •Years to stay — Change the time horizon
• •Home age — See how a 1970s fixer-upper vs. a 2020 build affects repair costs
• •Credit score — See how different FICO scores affect the mortgage rate and DTI ratio

Adjusting each slider shows green (+$10,000) or orange (-$5,000)delta indicators showing how much each parameter has changed from the original values. Click “Re-run” to instantly see updated results.

Most rent vs. buy calculators give one answer based on average assumptions. But life isn't average.

What if the HVAC dies in year 2? What if the market drops right after closing? What if appreciation is 8% instead of 4%? These aren't edge cases — they're real possibilities that dramatically change the outcome.

By running up to 1,000 simulations, the distribution of outcomes becomes visible — not just the average. The results show:

• •How often buying wins vs. renting wins
• •How many futures end in financial stress (depleted reserves)
• •Which variables matter most (down payment, surplus, repair luck)
• •Whether the scenario is at a tipping point or has a clear winner

This tool is designed to provide directional insight, not financial advice. Here's what it doesn't account for:

• •Tax deductions (mortgage interest, property tax) — though these are less valuable post-2017 TCJA
• •Transaction costs when selling (realtor fees, closing costs)
• •Lifestyle preferences (stability, flexibility, pride of ownership)
• •Job changes, family growth, or other life events
• •Refinancing opportunities or ARM rate adjustments

Use this as one input in any decision, not the only input. Consult a financial advisor for personalized guidance.