What Is Home Equity? How It Grows, and What It Costs to Use

Buy a $400,000 house with $40,000 down and you own 10% of it on day one; in every practical sense, the lender owns the rest. Ten years later, with nothing beyond the regular payment and 3% a year of price growth, your slice is about $232,000, or 43% of a house now worth roughly $538,000. Most of that gain did not come from your payments. This guide separates the two engines that build equity, shows the whole decade in one table, and then prices the three ways people borrow against it.

What home equity is, and what it is not

Home equity is the current market value of your home minus everything owed against it: the first mortgage plus any credit line or second loan secured by the house. Two things follow from that definition. First, the number is an estimate, because the value half of it is what a buyer would pay today, and you only find that out for certain at a sale or an appraisal. Second, equity is not money. It is a claim on the proceeds of a sale that has not happened, which is why the last sections of this guide matter as much as the first.

Engine one: paying the loan down

On a $360,000 loan at 6.5% over 30 years, the payment is about $2,275 a month, and in the first year only about $4,000 of the $27,300 you send is principal. The rest is interest. That split tilts slowly in your favor: by year ten the same payment is retiring about $7,200 of principal a year, and by the final years nearly all of it is. Paydown is reliable and slow, and it is the only engine you control directly, because extra principal payments speed it up on your schedule. The amortization calculator shows the exact split for any loan, month by month.

Engine two: appreciation

The second engine works on the whole house, not just the part you paid for. If the $400,000 home gains 3% in its first year, that is $12,000 of equity, three times what the payments contributed, and it accrued on the 90% of the house the lender financed. That is leverage, and it is the reason homeownership has built so much household wealth: a modest return on a large borrowed asset. The table puts both engines side by side for the full decade, rounded to the nearest hundred.

Of the $232,400 at year ten, $40,000 was the down payment, $54,800 came from payments, and $137,600 came from the market. Change the appreciation assumption to 0% and the decade ends at $94,800 of equity. Leverage amplifies whatever the market does, which is the whole point in a rising market and the whole problem in a falling one.

Equity is not cash

The $232,400 is real, but it is locked in a house. Selling converts it to cash only after commissions, transfer taxes, and preparation costs that commonly run 6–10% of the price, which on the year-ten house is $32,000–$54,000 before you see a dollar. The value half can also move against you: national home prices fell by roughly a quarter in the late-2000s bust and took years to recover, and a buyer with 10% down at the peak was underwater within a year. In between selling and holding, the only way to touch equity is to borrow against it, and that is where the costs live.

Three ways to use it, and what each one costs

Lenders will generally let total borrowing against the house reach about 80–85% of its value. On the year-five numbers, 80% of $463,700 is about $371,000, minus the $337,000 still owed, so roughly $34,000 is reachable; by year ten the same rule frees up about $125,000. How you reach it matters:

• A home equity line of credit is a revolving account secured by the house: you draw what you need during a draw period, often paying interest only, then repay over a fixed stretch afterward. The rate is usually variable, so the payment can climb, and the jump from interest-only to full repayment surprises people. The HELOC calculator shows the available line on your numbers and what the payment looks like in both phases. The home equity calculator projects the equity itself, paydown plus appreciation, year by year.
• A home equity loan is a lump sum with a fixed rate and a fixed payment, sitting behind the first mortgage as a second lien. It is the predictable option for a one-time, known amount, and it carries its own closing costs. The trade-offs against a HELOC are laid out in HELOC vs. home equity loan.
• A cash-out refinance replaces the entire mortgage with a larger one and hands you the difference. It resets the clock on the whole balance and reprices all of it at today's rate, which is fine when rates have fallen and expensive when your existing rate is well below the market. Full closing costs apply.

The risk in borrowing against it

Every one of those loans is secured by the house, so the downside of not paying is foreclosure rather than a collections call. The quieter risk is what the money is for. Equity grows because appreciation works on an asset you keep; borrow against it to fund consumption, and you have converted the engine into a second payment while the thing you bought depreciates. Stack a variable rate on top, then a soft housing market, and a household that maxed its line can find itself owing more than the house is worth with two lenders holding liens. The uses that tend to hold up are the ones that preserve or add value: improvements that raise the home's worth, or retiring far more expensive debt with a plan that keeps it retired. A useful test before signing: would you sell a tenth of your house to pay for this?

Home equity is a net worth line rather than a bank balance, and it deserves to be tracked like one, with the value and the loans moving against each other in the open. Net worth tracking keeps the house, the mortgage, and any line against it in a single view that changes as both engines run.