HELOC Calculator
A home equity line of credit (HELOC) leaves your first mortgage alone and adds a variable-rate line behind it. The bigger risk is the payment step-up when the interest-only draw period ends.
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Educational estimates only. Not financial, tax, or lending advice.
Updated
How does a HELOC work, and what is the risk?
A HELOC is a revolving line secured against your equity. During the draw period you can borrow and repay repeatedly, and many lenders require only interest, which retires none of the balance. When the draw period ends, the line converts to a repaying loan over a shorter term, and the payment jumps. Because the rate is variable, it can jump again. Use the rate stress field below to test that: set it to 2 or 4 points and see whether the payment still works.
Over your 26-year stay
Your first mortgage is untouched, so its rate is safe. The second payment is what moves, and it moves twice: when the draw period ends, and whenever the prime rate does.
- Keep current
- Monthly payment
- $2,767
- Net cost over your stay
- $687,691
- vs keeping your mortgage
- —
- Break-even, ours
- —
- Break-even, conventional
- —
- HELOC + mortgage
- Monthly payment
- $3,100
- Net cost over your stay
- $775,620
- vs keeping your mortgage
- -$87,929
- Break-even, ours
- Never recovers
- Break-even, conventional
- No monthly saving
Why two break-even figures? The conventional figure counts only the monthly payment saving against the cash you pay upfront. Ours also counts what you still owe when you sell, which is why the two disagree.
Compared over
the 26 years you expect to stay
Two break-even figures. The conventional figure counts only the monthly payment saving against the cash you pay upfront. Ours also counts what you still owe when you sell, which is why the two disagree.
| Leave it alone | Borrow beside it | |
|---|---|---|
| Measure | Keep current | HELOC + mortgage |
| Interest rateThe rate on the new or largest loan in this scenario. | 6.875% | 8% |
| Starting loan balance | $320,000Low | $370,000 |
| Starting LTV (loan-to-value) | 71.1% | 82.2% combined |
| Principal & interest | $2,204Low | $2,537 |
| Extra principalVoluntary principal on top of the scheduled payment. Part of what you pay each month, so it belongs in the all-in figure. | — | — |
| PMI | — | — |
| Property tax + insuranceIdentical across every scenario for the same home, but a real part of the monthly bill. | $563 | $563 |
| Monthly HOA dues | — | — |
| All-in monthly payment | $2,767Low | $3,100 |
| Total closing costs | NoneLow | $500 |
| Cash you have to put inClosing costs paid in cash, plus any lump sum or one-time payment this option needs upfront. | NoneLow | $500 |
| Monthly commitment on topMoney you have to keep finding every month beyond the required payment: voluntary extra principal, or the same money invested instead. The required payment itself is the all-in figure above. | NoneLow | NoneLow |
| Cash received | None | $50,000 |
| Interest over 26 years | $367,691Low | $455,120 |
| Balance left after 26 yearsWhat you would still owe when you expect to sell or refinance again. | $0Low | $17,131 |
| Equity after 26 yearsHome value less the balance owed. Uses your assumed appreciation rate, which is 0% unless you change it. It is never used to remove mortgage insurance early. | $450,000Low | $432,869 |
| Invested balance after 26 yearsOnly the growth on this account is credited against net cost. The contributions are money you paid in, so counting the whole balance would count them twice. | — | — |
| Net cost over your planned stayCash closing costs + payments made + balance still owed − cash received. Excludes property tax, insurance and HOA, which are identical across scenarios. | $687,691Low | $775,620 |
| Savings vs keeping your mortgageThis is not the same as interest saved: it also counts the balance you still owe at the end of your stay and any cash you paid upfront. The row above reconciles the two. | BaselineLow | -$87,929 |
| Why that differs from interest saved | — | $87,429 more interest, less $50,000 of extra balance you start out owing, less $500 paid in cash at closing, plus $50,000 of cash you received — leaving you $87,929 worse off. |
| Break-even point, ours“Ahead from month 1” means there was no upfront cost to recover. “Never recovers” means the costs are never paid back. | — | Never recovers |
| Break-even point, conventionalUpfront cash divided by the monthly payment saving. This is the number most people mean by break-even, and it flatters a refinance: it ignores the principal you stop paying down when the term restarts. The equity-adjusted figure above is the one to rank on. | — | No monthly saving |
| Time to payoff | 26 yearsLow | 30 years |
| Total interest, full term | $367,691Low | $458,063 |
| Lifetime cost (interest + costs) | $367,691Low | $458,563 |
How to read this: “Low” marks the lowest figure among the scenarios shown and is not a recommendation. Net cost counts payments made plus the balance still owed at the end of your stay, minus cash received, which is what makes loans of different sizes and terms comparable.
Full amortization schedule
Every payment, month by month: how much goes to interest, how much retires principal, and what you still owe afterwards. The last money column is the all-in cost (principal, interest, any extra you send, mortgage insurance, property tax, homeowners insurance and HOA dues), which is what leaves your account. Switch to the annual view for a year-by-year summary. Printing and the CSV both follow whichever view you are in, so a year-by-year download gives a year-by-year file, which opens in Excel, Google Sheets and Numbers.
| Month | Payment date | Beginning balance | Payment | Principal | Interest | Extra principal | Ending balance | Cumulative interest | Mortgage insurance | Taxes & insurance | HOA | Total monthly cost | LTV |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Jan 01, 2026 | $320,000.00 | $2,204.15 | $370.82 | $1,833.33 | — | $319,629.18 | $1,833.33 | — | $562.50 | — | $2,766.65 | 71.0% |
| 2 | Feb 01, 2026 | $319,629.18 | $2,204.15 | $372.94 | $1,831.21 | — | $319,256.24 | $3,664.54 | — | $562.50 | — | $2,766.65 | 71.0% |
| 3 | Mar 01, 2026 | $319,256.24 | $2,204.15 | $375.08 | $1,829.07 | — | $318,881.16 | $5,493.61 | — | $562.50 | — | $2,766.65 | 70.9% |
| 4 | Apr 01, 2026 | $318,881.16 | $2,204.15 | $377.23 | $1,826.92 | — | $318,503.93 | $7,320.53 | — | $562.50 | — | $2,766.65 | 70.8% |
| 5 | May 01, 2026 | $318,503.93 | $2,204.15 | $379.39 | $1,824.76 | — | $318,124.54 | $9,145.29 | — | $562.50 | — | $2,766.65 | 70.7% |
| 6 | Jun 01, 2026 | $318,124.54 | $2,204.15 | $381.56 | $1,822.59 | — | $317,742.98 | $10,967.88 | — | $562.50 | — | $2,766.65 | 70.6% |
| 7 | Jul 01, 2026 | $317,742.98 | $2,204.15 | $383.75 | $1,820.40 | — | $317,359.23 | $12,788.28 | — | $562.50 | — | $2,766.65 | 70.5% |
| 8 | Aug 01, 2026 | $317,359.23 | $2,204.15 | $385.95 | $1,818.20 | — | $316,973.28 | $14,606.48 | — | $562.50 | — | $2,766.65 | 70.4% |
| 9 | Sep 01, 2026 | $316,973.28 | $2,204.15 | $388.16 | $1,815.99 | — | $316,585.12 | $16,422.47 | — | $562.50 | — | $2,766.65 | 70.3% |
| 10 | Oct 01, 2026 | $316,585.12 | $2,204.15 | $390.38 | $1,813.77 | — | $316,194.74 | $18,236.24 | — | $562.50 | — | $2,766.65 | 70.3% |
| 11 | Nov 01, 2026 | $316,194.74 | $2,204.15 | $392.62 | $1,811.53 | — | $315,802.12 | $20,047.77 | — | $562.50 | — | $2,766.65 | 70.2% |
| 12 | Dec 01, 2026 | $315,802.12 | $2,204.15 | $394.87 | $1,809.28 | — | $315,407.25 | $21,857.05 | — | $562.50 | — | $2,766.65 | 70.1% |
Showing 1–12 of 312 payments
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Each file is generated in your browser, and nothing is uploaded. Scenarios with a second lien include a separate block for each loan.
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Educational estimates only. Not financial, tax, or lending advice. Want every option side by side instead? Open the full comparison.
The draw period and the repayment period
The draw period and the repayment period behave so differently that budgeting for the first tells you almost nothing about the second.
| Draw period | Repayment period | |
|---|---|---|
| Typical length | 5–10 years | 10–20 years after it |
| Can you borrow more? | Yes, up to the limit | No, the line is closed |
| What the payment covers | Interest only, at many lenders | Principal and interest |
| What happens to the balance | Unchanged unless you choose to repay | Retired to zero by the end of the term |
| Rate | Variable | Variable at most lenders |
General structure only. Draw lengths, whether principal is required during the draw, and conversion options all differ by lender and by product.
The draw payment is low because it retires none of the debt, and ten years is long enough to stop noticing that. When the step-up arrives, the balance is still where it started.
The step-up, in numbers
Even with no rate rise at all, the payment on the line climbs by more than a third.
Take $60,000 drawn against a home worth $600,000, at 8.5%, with a ten-year interest-only draw followed by fifteen years of repayment. The first mortgage, $300,000 at 3.5%, is not touched, so its $1,631.04 payment never changes.
| Months 1–120 | Month 121 onward | |
|---|---|---|
| Payment on the line | $425.00 | $590.84 |
| Balance still owed | $60,000 | $60,000 |
| First mortgage payment | $1,631.04 | $1,631.04 |
| Both payments together | $2,056.04 | $2,221.88 |
Computed by the same engine as the calculator above and re-checked against it on every build. Assumes the rate does not move, which is the optimistic case.
Look at the middle row. After ten years and $51,000 of payments, the balance is exactly what it was on day one, which is how interest-only payments work.
That assumes the rate never moves. Because it is variable, the step-up adds to whatever prime has done in the meantime. Over the same ten years, a HELOC on these figures costs about $0.86 for every dollar raised, against $0.64 through a fixed home equity loan and $2.48 through a cash-out refinance that re-prices the whole mortgage.
HELOC vs home equity loan, costed side by side on one set of figures
HELOC questions
- What happens to a HELOC payment when the draw period ends?
- It steps up, often sharply, because the interest-only period retired none of the balance. On a $60,000 line at 8.5% with a ten-year interest-only draw and a fifteen-year repayment period, the payment on the line goes from $425 to $591 in a single month. Every dollar borrowed is still owed, and it now has to amortize over the shorter remaining term. The step-up is scheduled from the day you sign, not triggered by anything you do.
- Can a HELOC payment rise before the draw period ends?
- Yes. A HELOC rate is variable, usually quoted as a margin over the prime rate, so the payment moves whenever prime does. During an interest-only draw the whole payment is interest, which means a rate rise passes through to it almost in full. The rate stress field in the calculator exists for this: set it to 2 or 4 points and check the payment against a budget rather than against hope.
- How much can I borrow on a HELOC?
- Lenders size a line against combined loan-to-value (the first mortgage plus the line, measured against the home's appraised value) and commonly cap it somewhere around 80% to 85%, though this varies by lender, occupancy and credit profile. This calculator prices whatever amount you enter and shows the resulting CLTV; it does not decide what any lender will approve, and nothing here is an offer or an indication of eligibility.
- Does a HELOC affect my first mortgage rate?
- No. A HELOC is a second lien recorded behind the first mortgage, and the first loan's rate, balance, payment and payoff date are untouched. That is the structural reason a second lien is often cheaper overall than a cash-out refinance for a borrower holding a below-market rate: the higher rate applies only to the money borrowed, not to the entire balance.