What is opportunity cost in a rent vs buy decision?

Opportunity cost is the return you forgo by using your capital for a down payment instead of investing it. A $100,000 down payment invested at 7% annually for 10 years becomes $197,000. If your home equity grows by less than that over the same period, the renter who invested the down payment comes out ahead — even after paying rent.

Does the calculator account for the down payment being invested by the renter?

Yes. The renter scenario assumes the full down payment plus buying closing costs are invested from day one at the assumed stock return rate. Monthly savings (when rent costs less than buying) are also invested. This is the financially honest comparison that most calculators skip or understate.

What if I'd spend the money instead of investing it?

The calculator models pure opportunity cost — the assumption that the renter actually invests. If you know you'd spend the money, the analysis favors buying more than the calculator shows. Most financial advisors still recommend modeling the invested case as the benchmark, since a home effectively forces saving in the form of equity.

Rent vs Buy Opportunity Cost Calculator

The true cost of a down payment is what it would have earned invested in the market. This calculator models that cost explicitly across 5,000 scenarios.

Last updated: April 2026

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Rent vs Buy Calculator 2026

Updated with 2026 mortgage rates and current tax law

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What it does

Full opportunity cost modeling

Down payment + closing costs invested from day one. Monthly savings difference invested or liquidated dynamically.

Monte Carlo stock returns

5,000 paths with realistic stock return variability — not just the average.

Cost Breakdown tab

Shows opportunity cost explicitly alongside mortgage interest, taxes, and maintenance.

How to use Rent vs Buy Opportunity Cost Calculator

1
Enter your home price and down payment percentage
This determines the total capital you'd lock into the home purchase.
2
Set your stock return assumption
The default 7% reflects historical S&P 500 real returns. Use a lower number for a more conservative comparison.
3
See opportunity cost in the Cost Breakdown tab
The chart shows the estimated investment gains on your down payment + closing costs over your holding period — the cost of not investing that capital.
4
Compare to home equity growth
The net worth chart shows whether home equity growth outpaces what you'd earn by renting and investing the down payment.
5
Adjust holding period
Shorter holding periods favor renting (opportunity cost is large relative to short-term equity gains). Longer periods often favor buying.

When to use this

Evaluating whether to use savings for a down payment or invest

Enter your savings as the down payment. The net worth comparison shows whether investing beats home equity over your expected timeline.

FIRE community modeling renting + investing vs buying

Set stock return to 7% and compare to a typical 3.5% home appreciation. The opportunity cost is often the deciding factor for FIRE practitioners.

Why opportunity cost is the most underrated factor in rent vs buy math

Most people intuitively understand that rent is "money thrown away." But the down payment has a hidden cost that's just as real: the compounding investment returns you forgo by locking that capital in a home. A $120,000 down payment (20% of a $600K home) invested in index funds at 7% annual returns grows to $236,000 over 10 years — a $116,000 gain the buyer never sees. The home has to appreciate by enough to overcome this, plus cover transaction costs (3–6% buying, 5–6% selling) and all carrying costs. In slow-appreciation markets or short holding periods, it often doesn't.

Frequently Asked Questions

What is opportunity cost in a rent vs buy decision?: Opportunity cost is the return you forgo by using your capital for a down payment instead of investing it. A $100,000 down payment invested at 7% annually for 10 years becomes $197,000. If your home equity grows by less than that over the same period, the renter who invested the down payment comes out ahead — even after paying rent.
Does the calculator account for the down payment being invested by the renter?: Yes. The renter scenario assumes the full down payment plus buying closing costs are invested from day one at the assumed stock return rate. Monthly savings (when rent costs less than buying) are also invested. This is the financially honest comparison that most calculators skip or understate.
What if I'd spend the money instead of investing it?: The calculator models pure opportunity cost — the assumption that the renter actually invests. If you know you'd spend the money, the analysis favors buying more than the calculator shows. Most financial advisors still recommend modeling the invested case as the benchmark, since a home effectively forces saving in the form of equity.

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