HELOC Calculator

A HELOC (Home Equity Line of Credit) works in two phases: a draw period where you borrow as needed and pay interest only, followed by a repayment period where you pay back principal plus interest.

1. Enter your home value and mortgage balance to see how much credit is available (up to 80% LTV minus your balance).
2. Enter the draw amount - the portion of the credit line you plan to use.
3. Set your HELOC rate - HELOCs are usually variable, tied to the prime rate. Enter the current rate for your estimate.
4. Set the draw and repayment periods. Typical HELOCs have a 10-year draw period followed by a 10 or 20-year repayment period.

The calculator shows your interest-only payment during the draw period and the higher principal-plus-interest payment once repayment begins.

Available credit line:

Credit Line = (Home Value × 0.80) - Mortgage Balance

Example: $400,000 home, $250,000 mortgage. Credit line = $70,000.

Draw period payment (interest only):

Monthly Interest = Draw Amount × (Annual Rate / 12)

Example: $30,000 drawn at 9.0%. Monthly interest = $30,000 × 0.0075 = $225.00.

Repayment period payment (principal + interest):

M = P × [r(1+r)^n] / [(1+r)^n - 1]

The full draw balance becomes a standard amortizing loan at the start of the repayment period. On $30,000 at 9% for 20 years, the repayment payment is $269.92/month.

Note on variable rates: HELOC rates are typically prime + a margin. If the prime rate changes, your payment changes. The calculator uses a fixed rate for illustration.