HELOC Payment Calculator
U.S. Flagship #04Loans & MortgagesInterest-only draw vs. repayment payments.
Your HELOC
Enter your home's value to estimate your HELOC.
Advanced options
Enter your home's value to estimate your HELOC.
Know what this estimate is based on
- Jurisdiction
- United States HELOC planning model
- Rules and time period
- User-entered planning assumptions; the rate, index, margin, caps, and fees are not a live offer.
- Scope and limitations
- Variable-rate payment estimate only. Actual index, margin, rate caps, draw rules, minimum payments, fees, credit limit, appraisal, and eligibility are set by the creditor and agreement.
- Source links checked
- Jul 30, 2026
Built and regression-tested by Smart Tools Lab. It has not been individually reviewed by a licensed financial, tax, or legal professional.
How to use
- 01
Enter your home value, first-mortgage balance, the amount you've drawn on the line and your current rate.
- 02
Open Advanced to set the interest-only draw period, the repayment period, your lender's max combined LTV, a rate-rise stress test and a target CLTV.
- 03
Read the interest-only draw payment and the higher principal-and-interest repayment payment side by side.
- 04
Check your credit limit, available credit, combined LTV and the variable-rate impact before you borrow more.
Formula
Interest-only payment = drawn balance × annual rate ÷ 12. Repayment payment amortizes the balance: P × r ÷ (1 − (1 + r)^−n), where r is the monthly rate and n the number of repayment months. Credit limit = home value × max CLTV − first mortgage; available credit = credit limit − amount drawn; combined LTV = (first mortgage + drawn) ÷ home value.
Example
On a $500,000 home with a $280,000 first mortgage and an 85% CLTV cap, your credit limit is 500,000 × 0.85 − 280,000 = $145,000, leaving $85,000 still available after a $60,000 draw. At 8.5%, the interest-only draw payment is 60,000 × 0.085 ÷ 12 = $425 a month. Once a 20-year repayment begins, the fully-amortizing payment rises to about $521 — roughly $96 (23%) more — and your combined LTV sits at (280,000 + 60,000) ÷ 500,000 = 68%.
Definitions
- Draw period
- The opening years (often 5–10) when you can borrow against the line and usually pay interest only on what you've drawn.
- Repayment period
- The years after the draw ends when the balance is amortized with principal-and-interest payments — which is why the payment jumps.
- Credit limit
- The most the lender will lend on the line: home value × the maximum combined LTV, minus your first mortgage.
- Available credit
- Your credit limit minus what you've already drawn — the headroom still open to borrow.
- Combined LTV (CLTV)
- Every loan against the home — first mortgage plus the drawn HELOC — divided by the home's value; the figure lenders cap.
- Variable rate
- A HELOC rate typically tracks an index, so it can rise or fall over the life of the line and move your payment with it.
Good to know
What a HELOC actually is
A home equity line of credit, or HELOC, is a revolving loan secured by your home, much like a credit card whose limit is set by how much equity you hold. Instead of receiving a lump sum, you are approved for a maximum line and then borrow against it as you need to, paying interest only on what you have actually drawn rather than on the whole limit. That flexibility is the whole point: you can pull money for a renovation this year, repay it, and draw again for tuition next year without reapplying. It is this revolving structure that sets a HELOC apart from a home equity loan, which hands you a fixed sum at a fixed rate and a single set repayment schedule. A HELOC instead lives in two phases. During the draw period — commonly the first five to ten years — the line is open, you can borrow freely, and your required payment usually covers only the interest on your balance. When the draw period ends, the line closes to new borrowing and the repayment period begins, during which whatever you still owe is amortized into principal-and-interest payments over a fixed term. Understanding that two-phase shape is the key to using a HELOC well, because almost every surprise people run into — the payment that suddenly doubles, the balance that never seemed to fall, the rate that crept up — traces back to one of those two phases behaving exactly as designed.
The two payments, and why one is so much bigger
The single most important thing to understand about a HELOC is that it asks you for two very different payments at two different times. During the draw period the typical required payment is interest only, calculated simply as your drawn balance multiplied by the annual rate and divided by twelve. Because none of that payment touches principal, your balance does not fall on its own; pay the interest-only minimum for ten years and you will owe exactly what you started with. When repayment begins, the lender amortizes that remaining balance over the repayment term using the standard loan formula, so each payment now includes principal as well as interest. That repayment figure is almost always higher than the interest-only one, and the gap is the payment jump this calculator puts front and centre. How large the jump is depends on three things: how big the balance is, how long the repayment term is, and the rate. A small balance stretched over a long repayment term produces only a modest step up, while a large balance crammed into a short repayment term can more than double the payment overnight. Seeing both numbers side by side, before you ever sign, is what turns the jump from a nasty shock into a planned, budgeted event you have already decided you can handle.
Your credit limit, equity and combined LTV
How much you can borrow on a HELOC is governed by your equity and by a ratio lenders watch closely: the combined loan-to-value, or CLTV. Lenders set a maximum CLTV — most commonly somewhere between eighty and ninety percent — and your credit limit is your home's value multiplied by that cap, minus the balance of your first mortgage. On a five hundred thousand dollar home with a two hundred eighty thousand dollar mortgage and an eighty-five percent cap, the limit works out to one hundred forty-five thousand dollars. Whatever you have not yet drawn from that limit is your available credit, the headroom still open to you. Your combined LTV, meanwhile, adds your first mortgage and your drawn HELOC together and divides by the home's value; it is the number that tells you, and the lender, how much of the house is financed and how thin your equity cushion has become. A combined LTV comfortably below eighty percent leaves a healthy buffer; one creeping toward the lender's cap leaves very little room if home prices soften. This matters because a HELOC sits behind your first mortgage in priority, so the lender is acutely sensitive to how much equity stands between their loan and a loss. Watching your CLTV as you draw is the clearest way to keep borrowing from quietly outrunning the equity that backs it.
Reading the payment shock at the end of the draw
The end of the draw period is where well-meaning borrowers most often get caught out, because the change in payment can be abrupt and is easy to forget about years in advance. The mechanics are straightforward but unforgiving: on the last day of the draw, the lender takes whatever balance remains and recasts it into a fully amortizing loan over the repayment term. If you have paid interest only the whole time, that balance is the full amount you drew, and the new payment has to cover both principal and interest within a fixed number of years. The shorter that repayment window, the steeper the climb. A balance repaid over twenty years rises gently; the same balance squeezed into ten years rises far more. This calculator surfaces the exact figure so the jump is never a mystery, and it lets you test how lengthening or shortening the repayment period changes it. The practical lesson is to plan for the reset from the very beginning rather than treating the low draw-period payment as your true cost of borrowing. Ask yourself whether the repayment payment still fits your budget, not just the interest-only one, because that higher number is the commitment you are really making. Treating the comfortable early payment as the real one is how a manageable line of credit turns into a stretched household budget the moment the phase changes.
The variable-rate risk most borrowers underestimate
Unlike a fixed-rate mortgage, a HELOC almost always carries a variable rate, typically built as an index that moves with the market plus a fixed margin your lender adds. That means your rate — and therefore your payment — can rise even if you never borrow another dollar, which is a fundamentally different kind of risk from a loan whose payment is locked for its whole life. During the draw period the danger is subtle, because an interest-only payment moves directly with the rate: a balance that cost four hundred dollars a month at one rate can cost noticeably more if the rate climbs a couple of points. During repayment the same force pushes the principal-and-interest payment higher still. The rate-rise stress test in this tool exists precisely so you can see, before committing, what a realistic increase would do to both payments rather than hoping rates stay put. Many HELOCs include a lifetime rate cap that limits how high the rate can ever go; finding that cap and stress-testing your budget against it is one of the most useful things you can do before you draw heavily. The borrowers who handle HELOCs well are not the ones who guess where rates are headed — nobody can — but the ones who make sure they could still afford the payment if the rate rose to an uncomfortable level and were pleasantly surprised when it did not.
How much should you actually draw?
Just because a lender approves a large line does not mean drawing all of it is wise, and the right amount to borrow is usually well below the maximum. Every dollar you draw raises two things at once: your payment, in both phases, and your combined LTV, which thins the equity cushion protecting you against a fall in home prices. A useful discipline is to pick a target combined LTV you are comfortable staying under — often a few points below the lender's cap — and borrow only up to the point that keeps you there. This calculator translates that target directly into a safe-to-draw figure: the extra amount you could borrow while still landing at or under your chosen CLTV. It also shows three reference scenarios — a conservative draw, your current draw, and drawing the full limit — so you can see at a glance how the payment and the risk grade climb as you borrow more. Thinking in terms of utilization, the share of your limit you have actually drawn, helps too: a line drawn to the brim leaves no flexibility for a genuine emergency, while one used lightly keeps both your payment and your options open. The flexibility of a HELOC is its greatest strength, but only if you preserve some of it rather than treating the full approved limit as money that is meant to be spent.
Paying it off early and skipping the jump entirely
Because interest during the draw period is charged only on your outstanding balance, anything you pay above the interest-only minimum goes straight to principal and immediately reduces every future interest charge. This gives disciplined borrowers a powerful option that many never consider: paying the line down during the draw rather than coasting on the minimum. If you make a level payment large enough to clear the balance by the time the draw period ends, you walk into the repayment phase owing nothing and the dreaded payment jump simply never happens. The early-payoff figure in this tool shows the monthly payment that achieves exactly that, along with the interest you would save compared with riding the full interest-only-then-repayment schedule. The savings can be substantial, because every month you carry a balance under an interest-only structure is a month of pure interest with no progress on the principal. Even if clearing the whole balance is not realistic, paying something toward principal during the draw shrinks both the eventual repayment payment and the total interest. Before you commit to extra payments, confirm your lender applies them to principal and charges no prepayment penalty, which most HELOCs do not. Used this way, a HELOC becomes a remarkably flexible tool: cheap and low-commitment when you need breathing room, and quick to extinguish when you have the cash to do it.
Your options when the draw period ends
Reaching the end of the draw period does not have to mean simply accepting the higher repayment payment, and it pays to know your choices well before the deadline arrives. The default path is repayment: the lender recasts your balance into principal-and-interest payments and you settle the line over the repayment term, which is the figure this calculator highlights so you can decide in advance whether it fits. A second option, where the lender allows it, is to refinance the HELOC into a new line or roll it into a fresh first mortgage, which can reset the draw period or lock in a fixed rate but usually carries closing costs and depends on your equity and credit at the time. A third route some lenders offer is to convert the outstanding balance to a fixed-rate term loan, trading the uncertainty of a variable rate for predictable payments. Be alert, too, to the less common balloon structure, where instead of amortizing, the full balance falls due in a single lump sum at the end of the draw — a feature you want to discover when you sign, not when the bill arrives. The healthiest position is to enter the final year of the draw with a deliberate plan: either the balance is already low enough that the repayment payment is comfortable, you have lined up a refinance, or you have the cash to clear it. Borrowers who drift into the reset without a plan are the ones who feel trapped by it; those who treat the end of the draw as a known, dated event handle it on their own terms. Whatever path you choose, ask your lender to spell out exactly what happens at the transition before you ever draw on the line.
Common HELOC mistakes to avoid
A few recurring mistakes turn a sensible HELOC into a source of stress, and all of them are avoidable once you know the shape of the product. The first is treating the line like free money because the early payments are so low; an interest-only minimum flatters the true cost and tempts people to draw more than they would if they saw the repayment number. The second is forgetting the reset entirely, so the end of the draw period arrives as a genuine shock years after the line was opened. The third is ignoring the variable rate and assuming today's payment is tomorrow's, when a HELOC's defining feature is that the rate can move. The fourth is borrowing right up to the lender's cap, leaving no equity buffer and no headroom for an emergency. And the fifth is using a HELOC's flexibility to fund ongoing spending you cannot otherwise afford, which steadily converts your home equity into consumption rather than investment. The antidote to all of them is to look at the full picture before you draw: the repayment payment as well as the interest-only one, the combined LTV as well as the limit, and the stressed rate as well as the current one. This is general educational information rather than personalized financial advice, so weigh these numbers against your own circumstances and speak with a qualified professional before borrowing against your home.
Frequently asked questions
What is a HELOC draw period?
The opening phase — often 5 to 10 years — when you can borrow against the line and usually pay interest only on the amount you've drawn, which keeps payments low before repayment begins.
Why does my HELOC payment jump when repayment starts?
During the draw you pay interest only, so the balance never falls. When repayment begins you start paying down principal too, over a fixed term, so the monthly payment steps up — often sharply.
Is a HELOC interest rate fixed?
Usually not. Most HELOCs carry a variable rate tied to an index, so the payment can move even if you borrow nothing more. The rate-rise stress test shows how much a higher rate would add.
How is my HELOC credit limit set?
Lenders cap your combined loan-to-value, typically 80–90%. The limit is your home value times that cap, minus your first mortgage. Drawing less than the limit leaves available credit you can tap later.
What is combined LTV and why does it matter?
Combined LTV (CLTV) is your first mortgage plus the drawn HELOC, divided by the home's value. Lenders use it to cap borrowing, and a high CLTV leaves little equity cushion if home values dip.
Can I avoid the payment jump?
Paying more than the interest-only minimum during the draw — or a level payment that clears the balance by the time the draw ends — shrinks or removes the jump and cuts total interest. The early-payoff card shows the payment that does it.
What happens if my rate rises during the draw period?
Because the rate is variable, even the interest-only payment rises with it. The variable-rate impact table shows the new draw and repayment payments at your stress-tested rate.