How the HELOC scenarios are modeled
The HELOC calculator separates three simple views: interest-only cost on the current drawn balance, an amortizing repayment payment, and the same repayment calculation at a higher stress rate.
The draw-period illustration multiplies the entered balance by the entered annual rate and divides by 12, which is a simple monthly interest-only estimate. The repayment illustrations use the fixed-payment formula over the entered repayment months at the current assumed rate and at the higher stress rate. The higher rate is a scenario you choose, not a forecast.
Drawn balance × annual rate ÷ 12 ÷ 100Shows interest on the entered balance without principal repayment.
Standard fixed-payment formula over entered repayment monthsIllustrates what repayment could look like if the balance were amortized at a constant rate.
Same amortizing formula at the entered stress rateProvides a sensitivity scenario rather than a rate prediction.
Enter the amount you expect to have drawn, not the total unused credit line unless they are the same.
Enter a current-rate assumption and a repayment-period assumption.
Choose a higher stress rate to see how repayment sensitivity changes.
Compare the modeled results with the actual HELOC agreement’s draw, minimum-payment and rate-reset provisions.
Best used for
- Understanding interest-only carrying cost on a drawn balance
- Planning for a future amortizing repayment phase
- Stress-testing a higher-rate repayment scenario
What this tool does not answer
- Actual HELOC minimum-payment formulas vary by contract.
- The tool does not simulate future rate changes month by month.
- It does not model additional draws, freezes, fees or promotional periods.
How to read a sample result
Illustrative example: a $300,000 drawn balance at 6% has a simple interest-only illustration of $1,500 per month. Amortizing that balance over 180 months at 6% produces about $2,531.57; at a 9% stress rate the modeled payment rises to about $3,042.80.
The methodology below explains how this calculator treats the inputs and assumptions. Replace the sample values with your own planning figures. Results are estimates, not quotes, approvals, disclosures or recommendations.
Inputs and units
Drawn balance, current assumed rate, repayment years and higher stress rate. All currency entries are U.S. dollars. Percentage fields take a number such as 6 for six percent, not 0.06. Repayment terms marked in months use whole months; horizons marked in years use whole years.
Calculation workspace
Enter your own figures in the calculator above. The starting values are examples only. No personal identifiers are needed to run a scenario.
How to interpret the result
Read every result together with the assumptions you entered. Changing an input changes the scenario, not product availability. Displayed amounts are rounded for readability.
Assumptions and limitations
Actual minimum-payment formulas, promotional terms, draws and interest accrual differ by contract. No future rate is forecast.
Review more than one scenario
Run a base case and then change one uncertain input at a time. Compare a shorter holding period, a higher cost or a different repayment term where those inputs are supported. Record which costs have not been entered. A precise-looking number can still rest on uncertain assumptions.
Invalid inputs and error recovery
If an input is missing or outside the calculator’s supported range, the page will ask you to correct it. Use negative values only in fields that explicitly allow them. A calculation error is not a credit decision.
Model documentation
The calculator methodology explains the inputs, assumptions and supported models. Use the result for planning and compare it with the provider’s written terms and applicable disclosures before making a decision.
Choose a product for your calculation
Use these comparisons for planning; final eligibility, pricing and terms are set by the provider.
Program references and comparison sources
CFPB: What is a HELOC? — Revolving home-secured borrowing, draw and repayment periods, collateral risk.
Check the linked source for its effective date and applicable scope. A source link is not a lender partnership or an individual offer.