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Home Equity HELOC Calculator

See how large a home equity line of credit you could open, then estimate both the interest-only payment during the draw period and the bigger amortizing payment once repayment begins.

Written by TopicDrill Editorial Team·Updated June 2026

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Your home and line

Enter your numbers, then press Calculate.

$
$
$

Repayment payment

$521

Combined LTV after draw: 71.1%

Available credit line$122,500
Interest-only payment$425
Repayment payment$521
Total interest paid$115,967

Outstanding balance over time

Balance Draw ends
$0$15.0k$30.0k$45.0k$60.0k0 yr15 yr30 yr

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How the HELOC calculator works

A HELOC lets you borrow against the equity in your home using a revolving credit line. The tool starts by finding your maximum line size: it takes your home value times the lender's combined loan-to-value cap, then subtracts the mortgage you still owe. Whatever remains is the equity you can tap.

From there it splits the loan into two phases. During the draw period you usually pay interest only, so the balance stays flat. When repayment begins, the calculator amortizes the amount you borrowed over the remaining years, which is why the second payment is much larger. The chart traces your outstanding balance and marks where the draw period ends.

A worked example

Suppose your home is worth 450,000 dollars, you owe 260,000 dollars, and your lender allows an 85 percent combined loan-to-value. Your maximum line is 382,500 dollars minus 260,000 dollars, or about 122,500 dollars. Borrow 60,000 dollars at 8.5 percent with a 10-year draw and a 20-year payback, and you would pay roughly 425 dollars a month while drawing, then around 520 dollars a month once principal repayment kicks in.

Things to keep in mind

HELOC rates are usually variable, so a rising prime rate can lift your payment with little warning. Your home is the collateral, which means missed payments put it at risk. For a plain-language overview of how these lines work, see the CFPB guide to HELOCs. If you are weighing a single lump-sum loan instead of a revolving line, compare the cost with our loan calculator.

Frequently asked questions

How much can I borrow with a HELOC?

Lenders cap your total home debt at a combined loan-to-value limit, often 80 to 90 percent. Multiply your home value by that limit, then subtract your current mortgage balance. Whatever is left is the credit line you can be approved for, assuming your income and credit also qualify.

Why does my payment jump after the draw period?

During the draw period most HELOCs only require interest, so the payment is small and the balance never falls. When the repayment period begins you must pay back the principal too, spread over the remaining years. That shift from interest only to fully amortizing is what makes the payment rise sharply.

Is a HELOC rate fixed or variable?

Most HELOCs carry a variable rate tied to the prime rate, so your payment can move up or down over time. This calculator uses a single rate you enter to show one scenario. To stress test, run it again with a higher rate to see how much the repayment payment could grow.

What is combined loan-to-value, or CLTV?

Combined loan-to-value is all the debt secured by your home divided by the home value, then multiplied by 100. If your mortgage plus the new draw equals 320,000 dollars on a 400,000 dollar home, your CLTV is 80 percent. A lower CLTV usually means a better rate and a larger approved line.

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