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Mortgage Calculators

HELOC Payment Calculator

Estimate HELOC payments during the interest-only draw period and the amortized repayment period.

Standard HELOC structure: interest-only during draw, then fully amortized over the repayment period.

$
%
yr
yr
Interest-only draw payment
$354/mo
Jumps to $434/mo when repayment begins.
Draw phase monthly
$354
Repayment phase monthly
$434
Interest during draw
$42,500
Interest during repayment
$54,139
Total interest (both phases)
$96,639
Explain this result

Turn the numbers above into plain-language takeaways. Educational only — not financial advice.

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Overview

How the HELOC Payment Calculator Works

A home equity line of credit has two very different phases, and most borrowers only budget for the first. During the draw period you typically pay interest only, which feels cheap. When repayment begins, the outstanding balance amortizes over a shorter remaining term and the payment can double or triple overnight. This calculator shows both numbers up front so the second phase is not a surprise.

Formula

The Math Behind the Calculator

Draw-period payment (interest only) = Balance × (APR ÷ 12). Repayment-period payment = B × r / (1 − (1 + r)^−n), where B is the balance at the end of the draw, r is the monthly rate, and n is the repayment term in months. Available credit is usually limited to (Home Value × Max LTV) − First Mortgage Balance.

Example

A Worked Example

You draw $60,000 on a HELOC at 8.5%. During a 10-year draw period the interest-only payment is $425 a month, and after ten years you still owe the full $60,000 because none of it went to principal. When the 15-year repayment period starts, the payment jumps to $591 — and if the rate has drifted to 10%, it is $645. Paying an extra $200 a month during the draw period would leave a $36,000 balance instead, cutting the repayment payment to about $354.

How to use

How to Use the HELOC Payment Calculator

  1. 1Enter the amount you expect to draw, not the full credit line, unless you intend to use all of it.
  2. 2Enter the current HELOC APR — nearly always variable and tied to the prime rate plus a margin.
  3. 3Set the draw period, commonly 10 years, and the repayment period, commonly 15 or 20 years.
  4. 4Look at the repayment payment first and confirm your budget can absorb it before drawing.
  5. 5Re-run with a higher rate to stress-test, since HELOC rates move with the prime rate.
Interpretation

What the Results Mean

  • The draw-period payment covers interest only, so the balance does not fall unless you pay extra.
  • The repayment payment is the real obligation and the number your budget must survive.
  • The jump between the two is the payment shock that catches most HELOC borrowers at the end of the draw period.
  • Total interest across both phases shows the full price of using home equity rather than another form of credit.
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Smart Next Steps

What to explore next
Avoid

Common Mistakes to Avoid

  • Budgeting only for the interest-only payment and being unprepared for the amortized one.
  • Treating a HELOC as an emergency fund; the lender can freeze or reduce the line if home values fall.
  • Using home equity for depreciating purchases such as vehicles or holidays, putting the house behind a short-lived asset.
  • Ignoring that the rate is variable, so a two-point increase raises the payment immediately.
  • Missing annual fees, inactivity fees, or early-closure fees buried in the agreement.
Scope

Limitations of This Calculator

  • It assumes a constant rate. Real HELOCs are variable and reprice as the prime rate changes.
  • Draws and repayments are assumed to be a single balance, not the revolving pattern most borrowers actually use.
  • Annual fees, appraisal costs, closing costs, and inactivity fees are excluded.
  • It does not verify LTV eligibility or how much equity a lender would actually extend.
  • Interest deductibility depends on whether funds are used to buy, build, or substantially improve the home; tax treatment is not modeled.
Keep going

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FAQ

Frequently Asked Questions

How much can I borrow with a HELOC?+

Most lenders allow a combined loan-to-value of 80–85%. On a $400,000 home with a $250,000 mortgage at 85% CLTV, that is roughly $90,000 of available credit.

What happens when the draw period ends?+

You can no longer draw funds, and the outstanding balance converts to a fully amortizing loan over the repayment term. This is when payments rise sharply.

Is a HELOC rate fixed?+

Usually not. Most are variable, tied to the prime rate plus a margin, and adjust monthly. Some lenders let you lock portions of the balance at a fixed rate.

HELOC or home equity loan?+

A HELOC is a revolving line with a variable rate, best for staged expenses like a renovation. A home equity loan is a fixed-rate lump sum, better when you know the exact amount you need.

Can I lose my home with a HELOC?+

Yes. A HELOC is secured by your home as a second lien, so default can lead to foreclosure. That risk is the reason to be conservative about the amount drawn.

Financial Disclaimer

This calculator is for educational and estimation purposes only. It does not provide financial, mortgage, tax, investment, or legal advice. Actual rates, payments, taxes, fees, insurance costs, eligibility, and loan terms vary by lender, location, credit profile, and market conditions. Always compare official offers and consult a qualified professional before making financial decisions.

Last updated June 2026 · Prepared by the mCalculator Editorial Team