HELOC Calculator

Introduction

This HELOC Calculator estimates payments during the draw period and after the line enters repayment. Enter the credit line limit, amount drawn, variable rate, draw length, and repayment term to see interest-only cost now versus fully amortizing payments later when the revolving period ends.

Who this calculator is for

Homeowners choosing between a fixed home equity loan and a line of credit use this page to see how variable rates and interest-only draws affect cash flow. Contractors funding phased remodels or parents paying tuition in chunks often prefer HELOC flexibility but need a plan for the repayment cliff when draws stop.

For a fixed lump sum second mortgage, use the Home Equity Loan Calculator. First mortgage baseline payment remains in the Mortgage Calculator.

What it estimates

During the draw period the tool applies the entered rate to the outstanding balance for an interest-only monthly payment if that is the program structure. At repayment, the remaining balance amortizes over the repayment term at the same or updated rate assumption, producing a higher payment that includes principal.

Rate caps, floors, index plus margin resets, annual fee, inactivity fee, and minimum draw rules are not fully simulated. Payment shock when prime rises two points is a manual stress test you should run outside default inputs.

Inputs explained

Use the line limit and actual drawn amount, not always the full limit.

• Line of credit limit: Maximum the lender will allow; may exceed what you draw today.
• Amount drawn: Current or expected balance you will carry during draw.
• Interest rate: Current variable rate or stressed rate for planning.
• Draw period length: Years you may borrow and pay interest-only, often ten.
• Repayment period length: Years to amortize balance after draw ends, often ten or twenty.
• First mortgage balances (optional): For CLTV context with home value field if present.

How to read the results

Interest-only payment equals balance times monthly rate. Repayment payment jumps because principal must retire in the remaining term. Compare the repayment figure to your budget years before the cliff; many owners refi the combined debt with a cash-out first mortgage in the Refinance Calculator before repayment begins.

CLTV on a $80,000 draw against a $400,000 home with $250,000 first lien is 82.5 percent, which may block new draws or require principal paydown. Feed total housing payment into the Debt Ratio Calculator using repayment-phase payment for conservative DTI.

Worked example

HELOC limit $80,000 with $80,000 fully drawn at 8.50% variable during a ten-year interest-only draw: monthly interest about $567 with no principal reduction. After draw, a ten-year repayment amortizes $80,000 at 8.50%: payment near $992, roughly $425 higher than the interest-only phase.

If the rate rises to 10.50% at repayment start, the same amortization pushes payment above $1,080. That jump is the main HELOC risk this calculator illustrates.

Practical use cases

Fund a remodel in three draws and model average balance each year. Keep a HELOC as emergency liquidity but calculate cost if you fully draw it. Compare fixed HEL payment from the home equity loan calculator against worst-case HELOC repayment.

Before using HELOC to consolidate cards, ensure you will not rerun card balances after payoff. The calculator shows loan payment, not behavior change.

Limitations and related tools

Index changes monthly or quarterly on most lines; long-term rate paths are unknown. Some HELOCs require balloon payoff at end of repayment. Cross-default with first mortgage and foreclosure priority follow state law and note terms not modeled here.

Fixed second lien: Home Equity Loan Calculator. Purchase affordability: House Affordability Calculator. Equity basics: mortgage basics.

How It Works

1. Enter line and draw. Type credit limit and the balance you expect to carry during the draw period.
2. Set rate and periods. Enter current variable rate, draw period years, and repayment term years.
3. Calculate both phases. Run the tool and read interest-only payment now versus amortizing payment in repayment.
4. Stress-test rate up. Increase the rate one to two points and recalculate repayment payment before you rely on interest-only affordability.

Formula and methodology

The HELOC Calculator uses this identity for the scenario you enter. A bank, payroll system, or tax program may round on a 360-day year or average daily balance, so a statement can differ by a small amount.