HELOC Draw vs Repayment Cost Calculator

HELOC draw vs repayment cost calculator for payment shock and total interest

A HELOC usually has two phases: a draw period and a repayment period. In the draw period, many HELOCs are interest-only, meaning your minimum monthly payment mainly covers interest on the balance. That keeps payments low, but it does not reduce what you owe unless you voluntarily pay extra. When the draw period ends, the line typically converts into a repayment phase where you must pay principal and interest on a schedule. This is where many borrowers get surprised by a steep increase in the required monthly payment.

This calculator is designed for one primary decision: estimating how your minimum monthly payment may change when a HELOC shifts from draw to repayment, and what each phase costs in interest. It is not a full HELOC planning model, and it does not try to forecast future interest rate changes, new draws, or refinancing decisions. Instead, it focuses on a single, practical comparison that most people search for: “What will my payment be in repayment, compared to my draw payment, and how much interest am I paying?”

Start by entering your current HELOC balance and the draw-period APR. Then enter the draw and repayment lengths. If you expect your balance to be different by the end of the draw period (because you plan to borrow more, or pay down principal), use the Advanced option for “Expected balance at end of draw.” If your lender applies a different APR in repayment, enter a separate repayment APR. The results show the interest-only draw payment, total interest during the draw period (assuming the balance stays constant), the amortized repayment payment, and the total interest across the repayment schedule.

Assumptions and how to use this calculator

• The draw-period minimum payment is treated as interest-only, calculated from the draw APR and the draw-period balance.
• Total draw-period interest is estimated assuming the balance stays constant during the draw (no new draws and no principal paydown) unless you set a different end-of-draw balance.
• The repayment-period payment is calculated as a standard amortizing loan payment over the repayment term using the repayment APR and the end-of-draw balance.
• If you leave repayment APR blank, the calculator assumes the repayment APR equals the draw APR.
• Fees, closing costs, annual account charges, and tax effects are excluded because they vary by lender and borrower and can change the true cost materially.

Common questions

Why is my draw payment much lower than my repayment payment?

During the draw period, many HELOCs allow interest-only minimum payments. That means you are paying the interest due for that month, but you are not required to reduce the principal. Once repayment starts, you must pay back principal over a fixed number of months, so the required payment includes both interest and principal. The shorter the repayment term and the higher the balance, the larger the jump tends to be.

Does the draw period always mean interest-only payments?

No. Some HELOCs require principal payments even during the draw period, or they may have different minimum payment rules. This calculator assumes interest-only because it is the most common structure people mean when they search for draw vs repayment cost. If your HELOC requires principal during draw, treat this as a conservative estimate of the minimum draw payment and confirm your lender’s payment rules.

What should I enter for “Expected balance at end of draw”?

If you plan to keep borrowing, the end-of-draw balance may be higher than today. If you plan to pay down principal before repayment begins, it may be lower. If you do not know, leave it blank to assume the balance stays the same. Even small changes in end-of-draw balance can significantly change the repayment payment because amortization spreads principal across a fixed number of months.

What if the interest rate changes over time?

Many HELOCs have variable rates. This calculator uses a fixed APR for each phase to produce a clear comparison. If you expect rates to rise or fall, run a few scenarios by changing the APR values to see a reasonable range. For decision-making, focus on whether you can afford the repayment payment under a higher but plausible rate, not just today’s rate.

Is total interest in the draw period always “monthly interest times months”?

Only if the balance stays constant and you are not paying down principal. If you borrow more during the draw, interest costs rise. If you pay down principal, interest costs fall. This is why the calculator lets you set an end-of-draw balance. It is still a simplification, but it gives you a direct lever to model the most important real-world variable: the balance you carry into repayment.