HELOC Calculator Guide
Most HELOC quotes advertise the draw-period payment because it's the smallest number on the page. But a HELOC is really two loans stitched together on a timer, and the second one is the one that determines whether the line of credit was actually affordable. Understanding what happens at the handoff — and how a floating rate compounds that risk — matters more than the teaser rate you're quoted today.
Two Loans, One Account Number
During the draw period, you're effectively holding an interest-only loan with a revolving balance: borrow, repay, borrow again, with payments that only cover interest accrued. The moment the draw period ends, that same balance — whatever you've left outstanding — gets re-underwritten into a fully amortizing loan over the repayment term, with no further borrowing allowed. Run the numbers on a $60,000 balance at 8.5% and you'll see the gap directly: interest-only payments near $425 a month during the draw years, versus a principal-and-interest payment closer to $591 a month once repayment begins on a 15-year schedule. That's not a rounding difference — it's a permanent step up in your required monthly outlay, and it lands right as the "cheap" phase of the loan ends.
Why the Variable Rate Makes It Worse
Almost all HELOCs carry a variable rate tied to a benchmark like the prime rate, adjusted periodically over the life of the line. That's manageable during the draw period because interest-only payments move gently with small rate changes. It's far less forgiving during repayment, because the amortization math is recalculated against a live balance and a live rate — if rates have climbed since you opened the line, your fixed-looking repayment estimate was never actually fixed. A borrower who drew $60,000 at 6% might reasonably plan around a $506 repayment-period payment, only to see it reset closer to $574 if the index has moved up two points by the time draw ends. Re-run this calculator with a higher rate in the repayment years to see how sensitive your specific balance is before you assume today's estimate will hold for a decade.
HELOC vs. Home Equity Loan: Which Risk Do You Want?
This is the real decision most people are making without realizing it. A home equity loan gives you a fixed rate and a fixed payment on a lump sum from day one — you know the last payment amount before you sign. A HELOC trades that certainty for flexibility: draw only what you need, pay interest only on what's outstanding, and use it more like a financial cushion than a single expense. The tradeoff is that flexibility comes bundled with rate risk you don't fully feel until the repayment period arrives. If you're borrowing for one known expense — a renovation with a fixed budget, a debt consolidation payoff — a fixed-rate loan removes the reset risk entirely. If you want ongoing access to funds for irregular needs and can tolerate payment variability, the HELOC's structure makes more sense despite the uncertainty.
Either way, stress-test the repayment-period number against a higher rate than you're currently quoted, not just the current one. If a two- or three-point rate increase during repayment would strain your budget, that's worth knowing before you draw the full line rather than after. For a broader view of how this debt fits alongside your other obligations, a loan calculator or credit card payoff calculator can help you see the full picture. This is educational information rather than lending advice — a loan officer can tell you exactly how your specific HELOC's rate caps and adjustment schedule work before you commit.