The 20 Percent Rule and Why I Argue With It
Somebody's grandfather told them 20 percent down or don't bother. Probably good advice around 1985. I want to walk through why it deserves an argument in 2026, especially here in Utah County — and then you make your own call, because that's genuinely how I want this to go.
The rule, so we're working from the same version: put down 20 percent of the purchase price and you avoid private mortgage insurance, PMI — the fee lenders tack on when they think you're a bigger risk with less equity in the deal. Skip 20 percent and you pay PMI every month until you cross that equity line, usually somewhere between half a percent and one percent of the loan amount per year. On a $450,000 house, that might be $200 to $350 a month. Nobody enjoys writing that check. I get why the rule has staying power.
Now watch what happens when you try to hit 20 percent on a starter home around here.
The math I ran
Take a $450,000 house — not unusual for a smaller place in American Fork or Lehi right now. Twenty percent down is $90,000. Saving $800 a month, which is a solid, disciplined amount for a young couple, that's over nine years to get there. Nine years.
Meanwhile rent in this valley hasn't been sitting still. If rent climbs even modestly over those nine years, you're saving while your monthly outlay creeps up and your ability to save shrinks a little every year. And that $450,000 house probably isn't $450,000 anymore either.
So the strict-20-percent crowd is asking you to out-save a moving target, with money that's also being squeezed by rent increases, to avoid a monthly fee of a few hundred bucks. Write this down: PMI is not the enemy people think it is. It's a cost, and costs should be compared, not feared.
Running the comparison honestly
Put a 5 percent down purchase next to a 20 percent down purchase on the same house, because I want you to see both columns, not just the one that confirms what you already wanted.
At 5 percent down on that $450,000 house, you put in $22,500 and finance the rest — bigger loan, PMI added to your monthly payment, higher monthly cost. No way around it.
At 20 percent down, you finance less, no PMI, lower monthly payment. Also no way around it.
But here's the piece people skip: what did it cost you in time and rent to get from $22,500 to $90,000? If that took six extra years of renting at, say, $1,700 a month, that's over $122,000 spent on rent you'll never see again, chasing a down payment goal on a house that appreciated the whole time you were chasing it. I ran this more than once with different numbers and the answer keeps landing in the same place. For a lot of first-time buyers in this market, waiting for 20 percent costs more than PMI ever would.
That said — I'm not telling you to buy at 3 percent down with nothing left over. That's a different mistake, and we already spent a whole lesson on why your reserve fund is part of the down payment, not an afterthought. The argument isn't "put less down, always." It's "don't treat 20 percent as a moral requirement when the math might say otherwise for your situation."
What to actually do with this
Sit down with your real numbers, the ones from your actual budget, not the one you wish you had. Figure out what PMI would cost monthly at 5, 10, and 15 percent down. Figure out how long it would take to reach 20 percent at your real savings rate. Then put a realistic rent inflation number next to that timeline and see what it adds up to. Most people have never run this side by side. Maybe twenty minutes with a calculator, and it'll tell you more than any rule of thumb.
Same instinct that made that kitchen remodel work out for me a few years back — the one that came in three days early and $400 under budget, which I know I bring up more than the situation calls for. But I bring it up because it wasn't luck. It was running the numbers before I started swinging a hammer, not during. Buying a house is the same discipline. Do the arithmetic before you commit to a strategy, not while you're already living inside it.
Before next time
Run your own 5-versus-20 comparison using a real listing you've actually looked at, and bring the numbers to class. I want to see what you land on, not just tell you what I'd land on.