Rent vs Buy Calculator: The Real Math Behind the Decision

I Almost Made a 300,000 Mistake

Last year I was sitting at my kitchen table staring at two spreadsheets — one for renting, one for buying — and I genuinely could not figure out which path made more financial sense. I'd been renting a two-bedroom for about 1,850 a month, and a similar place down the street was listed at 385,000. Everyone around me kept saying "you're throwing money away on rent," which, honestly, is one of those phrases that sounds smart but falls apart the second you actually run the numbers.

So I ran the numbers. And then I ran them again because the first time I forgot to include PMI, HOA, and the opportunity cost of my down payment sitting in a house instead of an index fund. That second run changed everything.

The rent vs buy decision isn't intuitive. It's math.

The Variables Nobody Talks About

Most people compare their monthly rent to a potential mortgage payment and call it a day. That comparison is basically useless. Here's why — the mortgage payment is maybe 60% of what you'll actually spend on housing when you own. There's property tax (which goes up, by the way), homeowner's insurance, maintenance that averages about 1% of your home's value per year, and possibly PMI if you're putting less than 20% down. And then there's the sneaky one: opportunity cost on your down payment.

Think about it this way. If you put 77,000 down on that 385,000 house (20% down), that's 77,000 that could've been invested. At a historical average return of roughly 7% after inflation, that's about 5,390 in year one alone that you're giving up. Nobody mentions this at the open house.

Here's a side-by-side I put together for that exact scenario I was looking at:

Now, that table is a little unfair to buying because it doesn't account for equity buildup or home appreciation. But it's a reality check. The "true cost" of owning was almost double what I was paying in rent, at least in year one.

That formula looks clean on paper but getting real numbers into it is where people trip up. I used our

The Breakeven Year Is Everything

Here's the thing most rent-vs-buy analyses miss: time horizon matters more than almost any other variable. Buying a home has enormous upfront costs — closing costs alone run 2% to 5% of the purchase price, which on a 385,000 home is somewhere between 7,700 and 19,250. That's money you never get back.

So you need to stay long enough for appreciation and equity buildup to overcome those sunk costs.

In my scenario, assuming 3% annual home appreciation and 5% annual rent increases, the breakeven point was about 6.5 years. Meaning if I sold before that, I would've been better off renting and investing the difference. After 6.5 years, buying started winning — and the gap widened every year after that.

But change the appreciation rate to 2%? Breakeven jumped to almost 9 years. Change it to 4%? Dropped to under 5. That sensitivity is exactly why you can't just use a rule of thumb — you need to actually model your specific situation with your local market's numbers. I'd suggest plugging your numbers into our

And don't forget — if you're considering buying as an investment, the math shifts again. You'll want to look at things like

What I Actually Decided (And Why)

I kept renting.

Not because buying is bad — it's not. But because I wasn't confident I'd stay put for 7+ years, and at 6.8% interest rates, the math just didn't favor buying for a shorter timeline. I took the difference between what I was paying in rent and what I would've paid as an owner (roughly 1,500 a month, all-in) and dumped it into a brokerage account. After 14 months that account is sitting at about 23,400, which honestly feels pretty good.

If rates drop to the 5% range, I'll rerun everything. The

One more thing — if you're running these numbers and property taxes are a big factor in your area (looking at you, Texas and New Jersey), make sure you're using a

Also worth checking: if you're buying and planning to rent out part of the property (like a basement unit or ADU), you'll want to factor that rental income in. Our

Quick Sanity Checks Before You Decide

Before you commit either way, ask yourself these:

• Will you stay at least 5 years? (If no, renting almost always wins.)
• Is your all-in monthly cost of owning less than 1.5x your rent? If it's more than that, the math gets really hard to justify unless you're betting on serious appreciation.
• Do you have 6 months of expenses saved beyond your down payment?
• Are you buying because you want to, or because someone told you renting is "throwing money away"?

That last one matters more than people think. Run the numbers with our