HELOC Calculator

1. Enter Home value ($), Existing mortgage balance ($), and Maximum combined LTV (%). Use Credit limit override ($, optional) when the line limit should come directly from your entry.
2. Enter Current draw balance ($), Index rate (%), and Margin (%).
3. Enter Rate floor (%, optional), Rate cap (%, optional), and Expected annual rate change (pp/yr, optional) when you want those rate rules in the schedule.
4. Set Draw period (years), Repayment period (years), and Draw-period payment type. Add Extra draw-period payment ($, optional), Origination / closing fees ($, optional), or Annual fee ($, optional).
5. Select Calculate. After the result appears, select Copy result or Download result (.txt).

How the HELOC Calculator estimates available credit

The calculator first estimates a credit limit by multiplying Home value ($) by Maximum combined LTV (%) and subtracting Existing mortgage balance ($). Credit limit override ($, optional) replaces that estimate. Available credit is the limit used in the calculation minus Current draw balance ($), and the current draw cannot exceed that limit.

Home value ($): $450,000
Existing mortgage balance ($): $220,000
Maximum combined LTV (%): 80%
Credit limit: $140,000
Current draw balance ($): $30,000
Estimated available credit: $110,000

How the HELOC Calculator treats rates

Starting APR is Index rate (%) plus Margin (%), limited by Rate floor (%, optional) and Rate cap (%, optional). Interest-only uses the current balance and monthly rate. Principal & interest spreads the balance across the remaining months. Repayment-period payments are recalculated when the repayment phase starts and when a modeled rate changes.

Index rate (%): 8.00%
Margin (%): 0.50%
Current draw balance ($): $30,000
Interest-only payment: $212.50

Expected annual rate change (pp/yr, optional) changes the main schedule at modeled year boundaries. The Rate sensitivity table keeps the current draw balance and applies static shifts of -2, -1, 0, +1, +2, and +3 percentage points to the starting APR. It does not use the drift setting.

What the HELOC amortization schedule includes

Each row shows Month, Phase, APR, Payment, Principal, Interest, and Remaining balance. A zero Current draw balance ($) can produce no rows. The schedule can also stop when the balance reaches zero.

Home value ($), Maximum combined LTV (%), Draw period (years), and Repayment period (years) must be above zero. Maximum combined LTV (%) cannot exceed 100%; Draw period (years) stops at 30 years, and Repayment period (years) stops at 40 years. Index rate (%) and Margin (%) accept 0 to 30%. A Rate floor (%, optional) cannot exceed a Rate cap (%, optional).

Inputs that change the estimate

• Credit limit override ($, optional) changes the limit used for available credit and validation of Current draw balance ($).
• Draw-period payment type changes the first draw-period payment. Extra draw-period payment ($, optional) adds principal during the draw period.

When another financial calculator fits better

Browse Financial Calculators for loan, debt, pay, investing, housing, and savings tools. Use the Mortgage Calculator for a fixed-rate mortgage with taxes, insurance, HOA, or mortgage insurance. Use the Loan Calculator for a standard loan payment with an optional origination fee. Use the Amortization Calculator when you need a schedule for a loan balance, rate, term, and payment frequency.

The calculation runs in the browser on the numbers you enter. The page does not submit those values or fetch live rates, lender records, credit data, or qualification decisions.

Frequently asked questions