What a HELOC Actually Is
A home equity line of credit is a revolving credit line secured against your home. That one sentence contains both of the things that make it different from a mortgage. Revolving means it works like a credit card — you draw what you need, repay it, and draw again — rather than arriving as a single lump sum. Secured against your home means the interest rate is far lower than unsecured credit, and also that the house is what the lender takes if the debt is not repaid.
Because interest is charged only on what you have actually drawn, a HELOC is genuinely cheap for spending that arrives in stages: a renovation billed by phase, tuition paid term by term, a cash buffer you may never touch. Take one out for a single known expense you will draw in full on day one and you get most of the risk of a home equity loan with none of the certainty.
Draw Period vs. Repayment Period
Every HELOC runs in two phases, and the shift between them is where most of the surprises live.
During the draw period — commonly five to ten years — you can borrow up to your limit, and the minimum payment is normally interest only. On a $50,000 balance at 8% that is $333.33 a month, and none of it reduces what you owe. The balance simply sits there.
When the draw period ends, the line closes to new borrowing and the balance converts into an ordinary amortizing loan over the repayment period. Now every payment covers interest and principal, so on the same balance over 15 years the payment becomes $477.83 — about 43% higher, arriving in a single step on a date fixed years earlier.
That step is worth planning for rather than discovering. Shorten the repayment period and it gets steeper still; the same $50,000 over ten years rather than fifteen pushes the payment past $600. The schedule below the calculator shows the whole path, and the flat stretch of ending balances through the draw years makes the point better than any warning: five years of payments can leave the debt exactly where it started.
How This Calculator Works
Three standard pieces of arithmetic, shown openly rather than hidden.
Repayment payment = balance × i ÷ [ 1 − (1 + i)−n ]
where i = annual rate ÷ 12 and n = repayment months
Borrowing limit = (home value × LTV limit) − mortgage balance
The draw payment is simply one month's interest, which is why it never touches the debt. The repayment payment is the standard amortization formula, the same one behind any mortgage or car loan. The schedule underneath is not generated from those formulas but built month by month — interest accrued, payment applied, balance carried forward — and the two agree to the cent, which is a deliberate cross-check rather than a coincidence.
What Each Input Means
- Loan amount — the balance you expect to owe, not the credit limit you were approved for. If you have a $100,000 line and plan to draw $40,000, enter $40,000. Interest is charged on what is drawn.
- Interest rate — the annual rate. HELOC rates are usually variable, so treat whatever you enter as today's snapshot rather than a promise.
- Draw period — how long you can keep borrowing and paying interest only. Five and ten years are the common terms.
- Repayment period — how long you then have to clear the balance. This is the field with the most leverage over the size of the payment jump.
- Closing costs — appraisal, title, origination and similar charges, entered either as a dollar figure or as a percentage of the amount borrowed. Some lenders waive them, sometimes on condition that the line stays open for a set number of years.
- Paid upfront or deducted — whether you settle those costs separately or have them taken out of the money advanced to you.
- Annual fee — a maintenance charge some lenders apply for keeping the line open. It is counted here for the draw years, which is when the line is live.
Closing Costs, Annual Fees and APR
The interest rate prices the borrowing. The APR prices the whole deal, folding the closing costs and annual fee into one annual figure so two offers can be compared honestly. On the default figures an 8% line with $2,000 of closing costs and a $50 annual fee works out at roughly 8.56%. Half a point does not sound like much until you notice it is being charged on a balance you will hold for twenty years.
This matters most when lenders compete on the headline rate. An 8% line with $3,000 of fees can easily cost more than an 8.25% line with none, and only the APR surfaces that.
One deliberate difference worth stating plainly. The APR here is calculated the standard way: the rate at which the money you actually receive equals the full stream of payments you actually make, all 240 of them, including the interest-only years. Calculator.net returns a higher APR for the same inputs because its figure appears to discount only the repayment-period payments and leave the draw-period payments out — even though its own result row counts 240 payments. Excluding sixty real payments overstates the rate, so the correct method was kept rather than the matching number. Every other figure on this page reproduces theirs exactly.
How Much You Can Borrow, and Why
Lenders think in terms of combined loan-to-value: everything secured against the house, measured against what the house is worth. Take the value, multiply by the LTV limit, subtract the mortgage still outstanding, and what remains is the ceiling on the line of credit.
On a $600,000 home with $250,000 left on the mortgage and an 80% limit, that is $480,000 less $250,000, so $230,000. Move the limit to 90% and it becomes $290,000; drop to 70% and it falls to $170,000. The second tab runs each of those so you can see the whole range rather than a single answer, because the limit a particular lender will accept is one of the few variables here you can shop around for.
Two cautions. The ceiling is not an offer — credit score, income and debt-to-income ratio decide whether you are approved for any of it, and lenders commonly want debt-to-income at or below about 43%. And the value in the calculation is the lender's appraisal, not your own estimate, which is often the point at which a plan and reality part company.
HELOC vs. Home Equity Loan vs. Cash-Out Refinance
All three convert equity into spendable money and they suit genuinely different situations.
- HELOC — revolving, variable rate, interest charged only on what is drawn. Best when the spending is spread over time or the total is uncertain. The cost of that flexibility is a payment that can move.
- Home equity loan — a lump sum at a fixed rate with level payments from day one, and no payment jump later. Best for a single known cost, and the safer choice if a rising payment would be difficult to absorb.
- Cash-out refinance — replaces the existing mortgage with a larger one and pays out the difference. Worth considering only when the new rate is at or below the old one; refinancing a low-rate mortgage to release equity can cost far more than the extra borrowing is worth.
The general rule: uncertain and spread out points to a HELOC, single and known points to a home equity loan, and a cash-out refinance is worth the paperwork mainly when the rate on the whole mortgage improves.
The Risks This Calculator Cannot Show You
The arithmetic is exact. The assumptions behind it are simplifications, and being clear about them matters more than adding decimal places.
- The rate is held fixed, and real HELOC rates are not. This is the largest gap. Most HELOCs move with the prime rate, so the repayment payment shown here is one scenario rather than a commitment. Run the calculation two or three points higher before deciding you can afford it.
- The balance is assumed drawn and constant. In practice you might draw gradually, or repay principal during the draw years, either of which changes the interest.
- Your home secures the debt. Missed payments on a HELOC risk the house, which is what separates it from unsecured borrowing at any rate.
- Falling house prices can shrink or freeze a line that has already been approved — lenders may reduce or suspend an undrawn line if the value drops.
- Interest deductibility is conditional. Under current US rules, interest is generally deductible only where the funds are used to buy, build or substantially improve the home securing the loan, and other limits apply. Treat that as a question for a tax professional rather than an assumption.
Frequently Asked Questions
What is a HELOC and how does it work?
A home equity line of credit is a revolving credit line secured against your home, so it behaves more like a credit card than a mortgage. During the draw period you can borrow, repay and borrow again up to your limit, and the minimum payment is usually interest only. When the draw period ends the line closes to new borrowing and whatever you still owe converts into an ordinary amortizing loan for the repayment period.
What happens to my payment when the draw period ends?
It jumps, often sharply, because you stop paying interest alone and start repaying the principal as well. With the figures this page opens on, the payment goes from $333.33 a month during the draw period to $477.83 once repayment begins, an increase of about 43%. The jump gets larger the shorter the repayment period is, since the same balance has to be cleared in less time, and it is the single most common reason HELOC borrowers get caught out.
How much can I borrow with a HELOC?
Lenders work from a combined loan-to-value limit. Multiply your home's value by the LTV they allow, then subtract what you still owe on your mortgage. On a $600,000 home with a $250,000 mortgage and an 80% limit, that is $480,000 minus $250,000, so up to $230,000. The second tab does this for you. The limit is a ceiling rather than an offer, and credit score, income and debt-to-income ratio all decide whether you are approved for the full amount.
Are HELOC rates fixed or variable?
Almost always variable. Most HELOCs are priced at the prime rate plus a margin, so the rate moves whenever prime moves and your payment moves with it. This calculator holds the rate you enter constant for the whole term, which makes the arithmetic clear but understates the risk. Run it again a few points higher to see what a rate rise would do, particularly to the repayment-period payment.
What does APR include that the interest rate doesn't?
The interest rate prices the borrowing alone. APR folds in the costs of getting the loan as well, which here means closing costs and any annual fee, then expresses the whole package as a single yearly rate. That is why entering $2,000 of closing costs and a $50 annual fee on an 8% line pushes the APR to roughly 8.56%. Comparing two lenders on interest rate alone can be misleading when one of them charges materially more up front.
Should closing costs be paid upfront or deducted from the loan?
The total cost is close either way, but the two are not identical. Paying upfront means you receive the full amount you asked for and the money comes out of your pocket now. Deducting means you borrow the full amount but only receive the balance after costs, so you pay interest on money you never touched. Choose the deducted option here and the result card shows exactly what lands in your account.
Can I pay off a HELOC early?
Usually yes, and paying down principal during the draw period is the most effective move available to you. Every dollar of principal you repay early reduces the balance that has to be amortized later, which lowers the repayment-period payment and cuts total interest. Check your agreement first: some lenders apply an early closure fee if the line is closed within the first few years.
Is a HELOC or a home equity loan cheaper?
It depends on how you intend to use the money rather than on the headline rate. A home equity loan hands over a lump sum at a fixed rate with level payments from day one, which is predictable and usually better for a single known expense. A HELOC lets you draw only what you need when you need it and charges interest only on the drawn balance, which is cheaper for costs spread over time, but the variable rate means the payment can rise.
This calculator provides estimates for general informational purposes only and is not financial, lending or tax advice. It assumes a fixed interest rate for the whole term; most HELOCs carry variable rates, so actual payments may be higher or lower. Results do not include property taxes, insurance, or every fee a lender may charge, and they are not an offer of credit or a guarantee of approval. Confirm all figures with your lender and consider speaking with a qualified financial professional before borrowing against your home.