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HELOC Calculator

The most your lender lets all loans on the home add up to. Ask yours.

Your line could be up to $90,000.00.

The prime rate on Sep 30, 2026, a common HELOC index. Lenders add a margin: enter the rate you're offered.

Total Paid: $128,035.87
Amount Drawn: $50,000.00
Interest: $78,035.87
Interest-Only Payment$291.67
Your Line of Credit$90,000.00
Years 1–10, interest only$291.67
Years 11–30, repaying$387.65
Payment jump+$95.98 (33%)
Interest while drawing$35,000.00
Interest while repaying$43,035.87
Total interest$78,035.87
Repaying at 2 Points Higher$449.86

HELOC rates are usually variable, so these payments can change with the index your lender uses. The last line shows the repayment payment if your rate is 2 points higher by then. The CFPB on how HELOCs work

Assumes you draw the full amount at the start, pay only interest while you can draw, then pay it off in equal monthly payments, all at today's rate.

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Estimates for informational purposes only — not financial advice.

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How a Home Equity Line of Credit Works

A home equity line of credit, or HELOC, lets you borrow against the equity in your home as you need it, up to a limit. It has two stages. During the draw period you can borrow and, on some plans, pay only the interest. Then the repayment period begins: you can't borrow any more, and the balance is paid off with principal and interest, so the payment often rises sharply. This calculator shows the line your equity could support, both payments, the jump between them and the total interest.

How this calculator works

Estimates the line of credit your equity could support, the interest-only payment while you draw, the payment once repayment starts, and the total interest.

How it calculates

  1. Line of credit = home value × the lender's borrowing limit − your mortgage balance.
  2. Interest-only payment = amount borrowed × rate ÷ 12, paid every month of the draw period.
  3. Repayment payment = D × r ÷ (1 − (1 + r)^−n): the level payment that clears the amount borrowed, D, over the n months of the repayment period at the monthly rate r.
  4. Total interest adds the interest-only payments to the interest in the repayment schedule. The payment jump is the repayment payment minus the interest-only one.
  5. Also works out the repayment payment at a rate 2 percentage points higher, to show what a rising variable rate can do.

What it assumes

  • You borrow the full amount at the start and keep it through the draw period, paying only interest; borrowing less, or later, costs less.
  • One rate for the life of the line. HELOC rates are usually variable, so real payments move with the index.
  • No annual fees, closing costs or introductory rate, and repayment in equal monthly payments rather than a balloon.
  • The default rate is the U.S. prime rate on its date (Federal Reserve H.15), a common HELOC index; lenders add a margin.

Sources

Copy and figures last reviewed .

How we build and check all our calculators

Frequently Asked Questions

How much can I borrow with a HELOC?

Generally a share of your home's appraised value, minus what you still owe on your mortgage. The lender sets that share, called the combined loan-to-value limit. With an 85% limit, a $400,000 home and a $250,000 mortgage leave a line of up to $90,000. Lenders also look at your credit and income, which can make the line smaller.

Why does my HELOC payment go up after the draw period?

During the draw period some plans let you pay only the interest, so none of your payment reduces the balance. When repayment starts, that same balance has to be paid off, principal and interest, over the repayment period. Borrowing $50,000 at 7% costs $291.67 a month interest-only, then $387.65 a month over 20 years: a jump of about a third. A shorter repayment period makes the jump bigger.

Are HELOC rates fixed or variable?

Usually variable. The rate is an index, such as the U.S. prime rate, plus a margin your lender adds, so when the index rises your payment rises too, even if you borrow nothing more. Some plans let you convert part of the balance to a fixed rate, which is usually higher but more predictable. This calculator holds one rate for the whole loan and also shows what a rate 2 points higher would do to the repayment payment.

What are the risks of a HELOC?

Your home secures the line, so if you can't keep up with the payments you could lose it. Payments can rise with a variable rate and jump when repayment begins. Lenders can generally freeze or reduce the line if your home's value falls or your finances get worse. If you sell the home, you will generally have to pay off the line in full, and some plans require the whole balance at once at the end, as a balloon payment.

HELOC or cash-out refinance: which is better?

A HELOC leaves your current mortgage in place and lets you borrow as you go, usually at a variable rate. A cash-out refinance replaces your mortgage with a larger one; its closing costs are generally higher, and the new rate may be higher than your current one. If your mortgage rate is low, a HELOC keeps it. If you want one fixed payment, a cash-out refinance may suit you better. Compare both here and on the Refinance calculator.

Term Definitions

Home Value

Your home's current market value. The line of credit is figured from it, and a lender may order an appraisal to confirm it, so use a realistic number rather than a hopeful one.

Borrowing Limit (Combined Loan-to-Value)

Lenders cap how much can be borrowed against a home in total, as a percentage of its value: the combined loan-to-value, or CLTV. Your line is that share of the home's value minus what you owe on your mortgage. At an 85% limit, a $400,000 home supports $340,000 of borrowing; with a $250,000 mortgage, that leaves a line of up to $90,000. Limits differ from lender to lender, so ask yours.

Mortgage Balance

The unpaid principal on your mortgage, plus any other loan secured by the home, such as a home equity loan. Your latest mortgage statement shows it. It comes off your borrowing limit to give the line you can get.

Amount You'll Borrow

A HELOC lets you borrow up to your limit as you need it during the draw period, and you pay interest only on what you have drawn. This calculator assumes you draw this amount at the start and keep it through the draw period, which shows the most interest that amount can cost at this rate. Drawing less, or later, costs less.

Interest Rate (HELOC)

Most HELOCs have a variable rate made of an index plus a margin. A common index is the U.S. prime rate; the margin is the extra your lender adds. When the index moves, your rate and payments move with it. Some lenders offer a low introductory rate for the first months: enter the rate that applies after it ends for a steadier picture.

Draw Period

During the draw period you can borrow, repay and borrow again, up to your limit; the CFPB gives 10 years as an example. Some plans let you pay only the interest during this time, which keeps payments low but doesn't reduce what you owe. This calculator assumes interest-only payments.

Repayment Period

When the draw period ends you can't borrow any more, and the balance is paid off over the repayment period, often 10 or 20 years, with payments that cover principal as well as interest. That is why payments often rise sharply when repayment starts. Some plans instead require the whole balance at once, as a balloon payment.

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