💰 Finance calculator

HELOC Payment Calculator

Estimate your HELOC payments across both stages — the draw period and repayment period. See the interest-only or amortizing draw payment, the repayment payment, payment shock amount, total interest cost, and how extra monthly payments reduce what you owe over time.

Enter your HELOC details

Fill in your balance, rate, and timeline. Use a preset to get started, then adjust to match your actual HELOC terms.

🟢 HELOC details
🏠
Outstanding balance at start of calculation
%
Current variable or introductory rate
🔵 Timeline
📅
Time left you can still borrow from the line
⏳
Period to repay balance after draw ends
💳
Check your HELOC agreement
⚪ Optional scenarios
➕
Additional principal above minimum — reduces total interest
📈
Model a rate increase — e.g. +2 for a 2% rise

Two-phase formula

Draw (interest-only): Balance × (APR ÷ 12)
Repayment (amortized):
P × r ÷ (1 − (1 + r)^−n)
r = monthly rate · n = repayment months

Why payment shock happens

During the draw period you often pay interest only — the balance doesn't shrink. When repayment begins, you suddenly owe the full principal plus interest compressed into a shorter term. The jump can be 2–3× the draw payment.

Tip: the best way to reduce HELOC payment shock is to make voluntary principal payments during the draw period. Even $100–$200/month extra can meaningfully reduce the balance entering the repayment phase — use the extra payment field above to model the exact impact.
This calculator provides planning estimates only. Actual HELOC costs vary with variable rate changes, lender margins, fees, minimum draw requirements, and how your lender applies payments. Always verify with your HELOC agreement and consult a financial advisor before making borrowing decisions.

Frequently asked questions

Is a HELOC payment interest-only during the draw period?

Often yes — many HELOCs require only interest payments during the draw period, keeping monthly payments low. However, some lenders require principal and interest from the start. Always check your specific agreement. Interest-only payments mean the balance does not shrink, which makes repayment-period payment shock more severe.

What is HELOC payment shock?

Payment shock occurs when the HELOC moves from the draw period to the repayment period. The payment jumps because you now must repay the full remaining principal over a compressed term, on top of interest. On a $50K balance at 8.5% moving from a 5-year interest-only draw into a 15-year repayment, the payment can nearly triple.

Can I reduce HELOC interest with extra payments?

Yes. Extra payments applied to principal reduce the balance you carry into the repayment period, which lowers both the repayment payment and total interest paid. Even $100–$200 extra per month during the draw period can save thousands in total interest.

Does this calculator handle variable rate changes?

This calculator lets you model a simplified future rate adjustment using the "Future rate adjustment" field. It does not simulate monthly index fluctuations over time. For a conservative estimate, model a +1–2% rate increase to see worst-case payment scenarios.

Related finance calculators

Interest Expense Calculator Estimate borrowing cost from any balance, rate, and time period — with 360 vs 365 day basis. Compound Interest Calculator Model how a HELOC balance grows over time when interest compounds without paydown. Net Worth Calculator Factor your HELOC balance into total liabilities for a full financial picture. Total Liabilities Calculator Add your HELOC to mortgage, car loans, and other debts for a complete liability total.

Disclaimer

This calculator is for educational and planning purposes only. It does not provide financial, legal, or lending advice. Actual HELOC payments and costs vary based on your lender's terms, variable rate adjustments, fees, minimum draw requirements, and how payments are applied to principal vs interest. Always review your HELOC agreement and consult a qualified financial advisor.