Two apartments, same size, roughly the same age — and one neighborhood costs two or three times the other. At first glance it looks irrational. It isn't. Home prices rest on a surprisingly clear logic. Three big forces drag prices around: location, interest rates and lending rules, and supply. We'll take them one at a time, then tie all three back together with a single line: a price is, in the end, the present value of the future rent the property will produce. This isn't about nailing down what any specific neighborhood is worth right now. It's about building a feel for how prices form.

Location — what you're really buying is the spot

"Location, location, location." It's the most worn-out line in real estate, and the reason is plain: a building ages and can be renovated, but you can't move the plot it sits on. Just don't let "good location" stay a vague mood. Break it apart.

• Transit — how long it takes to reach work or downtown. A home five minutes' walk from a subway station and one that needs two bus transfers differ in the time you burn every single morning. That gap is baked into the price.
• Access to jobs — the closer you sit to areas packed with good jobs, the more people want to live there. That's the root reason demand piles up.
• School zones — families with kids will gladly pay more for a strong school and tutoring environment. That's why demand clusters around certain districts.
• Infrastructure and amenities — how close the big hospitals, parks, grocery stores, and cultural venues are. Stack up enough everyday convenience and a place becomes somewhere people want to live.

One way to frame it. Buying a home isn't buying bricks and concrete. It's closer to buying the bundle of conveniences that location hands you every day: saved commuting time, good schools, clean air, a hospital nearby. Same square footage, but the neighborhood with the thicker bundle costs more. And that bundle, once built, rarely disappears — which is why the value of location is so stubborn.

Interest rates and lending rules — the ceiling on what people can pay

The second force is the terms on which people borrow. Almost nobody buys a home outright in cash; they buy with a mortgage. So "how expensive a home can I buy" hangs less on the sticker price and more on how much I can repay each month — and that monthly payment is touchy about interest rates.

Let's get a feel with hypothetical numbers. Say a household can handle up to 1 million won a month in principal and interest. When rates are low, that same 1 million won supports a larger loan principal. When rates rise, the principal that same 1 million won can support shrinks. Put plainly: when rates go up, the ceiling on the price people can afford comes down; when rates fall, that ceiling rises. The home's value hasn't budged, yet the "wallet limit" of the people who can buy it has.

On top of that, government lending rules draw another ceiling. Two acronyms come up constantly in Korea.

• LTV (loan-to-value ratio) — the cap on how much you can borrow relative to the home's price. At an LTV of 50 percent, a 500-million-won home allows at most a 250-million-won loan. The rest you cover yourself.
• DSR (debt service ratio) — the cap on how much debt you repay each year relative to income. With an annual income of 50 million won and DSR capped at 40 percent, it's hard to land a loan whose yearly principal-and-interest tops 20 million won.

Run these two together and they cap how much people can borrow. That's why rates and lending rules act as the "accelerator and brake" of home prices. Neither touches a home's intrinsic value — but by dialing how much purchasing power can enter the market, they swing where prices go.

Supply — building takes time

The third force is supply: the volume of new homes hitting the market. You'd expect rising demand to draw out more supply and cool prices. Here real estate has a strange habit — a time lag.

When demand for phones or clothing rises, factories crank out more fast. Apartments don't work that way. Finding land, securing permits, breaking ground, finishing construction so people can move in — usually several years. So even when the signal "there aren't enough homes right now" is blaring, the new homes that answer it don't actually land on the market until much later.

The pattern this lag creates, step by step, looks like this.

1. Demand rises and prices climb.
2. Prices are up, so builders apply for permits and break ground to build more.
3. But by the time those homes are finished and move-ins start, years have passed and demand may have shifted again.
4. Flip it around: an area where supply dried up for a while can stay short of inventory for a long stretch when demand suddenly comes back, sending prices lurching.

So demand and supply don't mesh smoothly. The lag knocks them a beat out of step, and prices lurch. That's why people watch numbers like permit counts, construction starts, and scheduled move-in volume like hawks. Those figures are a trailer that previews "the supply of a few years from now."

Price = the present value of future rent

Now the lens that ties all three forces together: the idea that a home's price is the present value of the stream of rent it will generate going forward. Sounds abstract. Unpack it and it's simple.

Rent out a home and rent shows up every year. Buying the home is a lot like buying that entire "line of future rent" in one go. But 1 million won received next year isn't worth the same as 1 million won today; future money has to be shaved back into today's terms. Add up all that future rent converted into today's value, and you've got the home's theoretical price.

The nice part about this lens: it explains, in one stroke, why the three forces above move prices.

• Good location means more people want to live there, so the rent you can command is higher. The future rent stream itself thickens, so the present value — the price — rises.
• Interest rates act directly on the "discount rate" used to convert future money into today. Low rates shave future rent less, so present value grows; high rates shave more, so present value shrinks.
• Short supply pushes rent up; ample supply holds it down. Either way it changes the size of the future rent stream.

Real markets carry plenty this framework doesn't catch — expectations, policy, taxes. But the question "is this price high or low relative to the rent it can earn?" is an old yardstick for measuring froth. When the rental yield (annual rent divided by the home's price) gets unusually low, it's often read as a sign that price has sprinted out ahead of rent.

Cramming the three forces into one scene

Let's close with a hypothetical scene. Suppose a big company moves into a neighborhood and a subway line gets extended there. As location improves, more people want to live there and the future picture for collectible rent thickens. If it happens to be a low-rate period, the borrowing limit available to people grows, so they can shoulder higher prices. Yet new apartments take years to build, so supply can't rise right away. Demand jumps immediately, supply lags — and the stage is set for prices to drift upward.

Flip it: when rates rise and lending rules tighten, even the same neighborhood sees would-be buyers' wallet limits shrink, draining the force that propped prices up. These three forces always act at once, shoving and pulling at each other. That's why flat claims like "this neighborhood is guaranteed to rise" or "this is the bottom" are dangerous. What we can do is read which force is acting hardest right now and keep our balance by holding price up against the yardstick of rent.

A feel for prices sharpens the more numbers you look at. Estimate the price of a real listing from its location, size, and conditions, then check your guess against reality. It's the best way to internalize how these three forces are woven into the price.