HELOC Interest-Only Payment Calculator

Quickly model your credit line’s interest-only payment monthly. Adjust APR, margin, and balance in seconds. Export results, review examples, and make confident decisions now.

Enter your details

Choose how the APR is set.
$
$
Reduces balance used for interest-only calculation.
Used when Rate mode = Fixed APR.
Used when Rate mode = Variable.
Optional add-on, e.g., promo discount (negative) or add (positive).
Common lender conventions include 365 or 360.
$
Spread across payments in the estimate.
$
Downloads include the same number of rows.
Tip: For variable rates, the calculator uses Index + Margin + Adjustment, then applies floor and cap.

Example data table

Scenario Balance APR Frequency Method Fees Estimated Interest-Only Payment
Typical draw period payment $50,000 8.250% Monthly Daily accrual (365) $0 ≈ $342.47
Same balance with annual fee $50,000 8.250% Monthly Daily accrual (365) $75/year ≈ $348.72
Variable rate estimate $35,000 Index 5.000% + Margin 3.250% Biweekly Simple periodic $5/payment ≈ $116.35
Examples are illustrative. Your statement may compute interest using average daily balance, different cycle dates, or lender-specific conventions.

Formula used

Daily accrual method

Interest-only payment is estimated using daily accrual:

  • Interest = Balance × (APR ÷ 100) × (Days in period ÷ Day-count basis)
  • Total payment = Interest + Fees per payment

Simple periodic method

A simplified approach divides APR across payment periods:

  • Periodic rate = (APR ÷ 100) ÷ Payments per year
  • Interest = Balance × Periodic rate
  • Total payment = Interest + Fees per payment

For variable rates, the calculator uses: APR = Index + Margin + Adjustment, then applies floor and cap. Interest-only payments typically do not reduce principal unless you pay extra.

How to use this calculator

  1. Enter your drawn balance and choose fixed or variable rate mode.
  2. If variable, fill index rate, margin, and any adjustment; set floor and cap.
  3. Select payment frequency and the interest method your lender uses.
  4. Add fees if your lender charges annual or per-payment fees.
  5. Click Calculate to view results above the form.
  6. Use Download CSV or Download PDF to export the summary and schedule preview.
Reminder: During a HELOC draw period, minimum payments are often interest-only. If your lender requires principal payments or uses different statement cycles, adjust assumptions or consult your agreement.

Understanding interest-only draw payments

During a HELOC draw period, the minimum payment often covers interest only. The principal balance stays flat unless you voluntarily pay extra. This calculator estimates that minimum by applying your APR to the amount you have drawn, then converting it into a payment period.

How rate settings change the payment

A fixed rate uses the APR you enter. A variable rate is modeled as index plus margin, with an optional adjustment, then limited by the floor and cap. Because the rate is applied directly to the outstanding balance, small APR changes can noticeably move the interest-only bill. For example, raising APR from 8.00% to 9.00% adds about $41.67 per month on a $50,000 balance.

Choosing frequency and day-count assumptions

Lenders may compute interest daily using a 365 or 360 day basis, then bill monthly, biweekly, or weekly. Daily accrual multiplies the balance by APR and by days in the period divided by the day-count basis. The simple periodic method divides APR by payments per year for a quick estimate. If your lender uses 360, the same APR produces higher per‑day interest.

Reading the schedule and Plotly chart

The schedule preview shows dates, interest, fees, and the total payment for each period you display. The Plotly graph visualizes the same series so you can spot how payment size responds when you change rate mode, fees, or frequency. If your balance changes during the month, treat the chart as a planning guide, not a statement. Use it for planning.

Planning for the repayment phase

Interest-only payments can keep cash flow lower, but they do not reduce what you owe. Use the draw-period totals to budget for interest and fees, then think ahead to the repayment period when principal payments usually start. If you expect to pay down the line, enter an extra principal payment to see the lower interest-only cost. Consider saving the difference between interest-only and a full amortizing payment as a buffer.

FAQs

How is the interest-only payment calculated?

Interest is estimated from your balance and APR for each payment period. You can use daily accrual with a 360 or 365 basis, or a simple periodic rate. Fees are added per payment for an estimated total.

Why is my payment different from my lender’s statement?

Statements can use average daily balance, different cycle dates, compounding rules, and minimum fee thresholds. Variable rates may change mid‑cycle. Use the calculator for planning, then compare with your lender’s disclosures for exact billing.

What balance should I enter if I borrow and repay during the month?

Enter a representative balance, such as your expected average draw. If your balance swings widely, run multiple scenarios and bracket the result. The schedule and chart assume a constant balance during the periods shown.

How do floor and cap affect a variable rate?

The calculator computes index plus margin and any adjustment, then limits the result to your floor and cap. This prevents unrealistically low or high APR values and helps you model how contractual limits shape payments.

Do interest-only payments reduce my HELOC balance?

Not usually. An interest-only payment covers interest and fees, leaving principal unchanged. If you want principal to drop, add an extra payment to see the reduced balance used for interest in the estimate.

Can I include annual fees and per-payment charges?

Yes. Annual fees are spread across payments for the chosen frequency, and per‑payment fees are added directly. The summary shows both fee per payment and total fees over the draw period.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.