HELOC Calculator
Calculate your HELOC payment during the draw period and repayment period. See interest-only vs. fully-amortizing payments. Free HELOC calculator.
Reviewed for accuracy by Marcus Webb and the Blueprint Dynamics editorial team (last updated July 2026). Our calculators use primary-source formulas and are cross-checked against IRS publications, Fannie Mae guidelines, and Federal Reserve data. Learn more about our methodology.
Source: Federal Reserve, Freddie Mac, Bankrate national averages. Rates are approximate ranges for borrowers with good credit (700+). Actual rates depend on your credit score, loan-to-value ratio, and lender.
HELOC Calculator
See how large a home equity line of credit you can open — and how your payment changes when the draw period ends.
Most lenders allow borrowing up to 80–85% of your home's value minus what you owe.
Maximum HELOC Line
$145,000
Available equity: $145,000
Draw Period Payment
$1,027.08/mo
Interest only
Repayment Payment
$1,258.34/mo
Principal + interest
Your payment jumps from $1,027.08/mo to $1,258.34/mo when the draw period ends — an increase of $231.26/mo.
Borrowing $145,000. HELOCs use a variable rate, so your real payment can change over time.
Rate sensitivity
HELOCs are variable-rate. Here is how your payment moves if rates rise.
| Interest Rate | Draw Payment | Repayment Payment |
|---|---|---|
| 8.50%current | $1,027.08/mo | $1,258.34/mo |
| 9.50%+1% | $1,147.92/mo | $1,351.59/mo |
| 10.50%+2% | $1,268.75/mo | $1,447.65/mo |
| 11.50%+3% | $1,389.58/mo | $1,546.32/mo |
What is a HELOC and how does it work?
A Home Equity Line of Credit (HELOC) is a revolving line of credit secured by your home equity — the difference between your home's current market value and your outstanding mortgage balance. Unlike a traditional loan that delivers a lump sum, a HELOC functions more like a credit card: you're approved for a maximum credit limit and draw funds as needed, repay them, and draw again. This revolving structure makes it particularly well-suited for expenses that unfold over time.
HELOCs operate in two phases. During the draw period (typically 5–10 years), you can borrow up to your credit limit, and most lenders require interest-only payments on the outstanding balance. After the draw period ends, the repayment period begins (typically 10–20 years), during which you can no longer borrow and your full balance amortizes into fixed monthly payments of principal plus interest.
How HELOC rates and limits are determined
Most HELOCs use variable interest rates tied to the Prime Rate (which moves with the federal funds rate), plus a margin of 0–2% depending on your credit profile and lender. When the Fed raises rates, your HELOC payment rises within the next billing cycle — there is no fixed-rate protection unless you exercise a rate-lock option (offered by some lenders for a portion of the balance). Lenders typically allow you to borrow up to 80–90% of your home's appraised value minus your mortgage balance. On a $400,000 home with $250,000 remaining on the mortgage at 85% CLTV limit: maximum HELOC = ($400,000 × 85%) − $250,000 = $90,000.
Best uses for a HELOC
HELOCs work best for ongoing costs with uncertain totals: multi-phase home renovations (draw as each phase is completed), funding a small business's working capital, spreading education costs over several semesters, or as a financial backstop for landlords managing multiple properties. The revolving structure means you only pay interest on what you've actually drawn — a $90,000 HELOC with $20,000 drawn costs interest on $20,000, not the full limit.
The risks to understand before opening a HELOC
Variable rate risk: rates can rise significantly. A HELOC at Prime + 0.5% in a low-rate environment might be 4.5% — but if the Prime Rate rises 3 percentage points, your rate climbs to 7.5%, increasing monthly interest costs by 67% on the same balance. Payment shock at end of draw period: interest-only payments during the draw period can give a false sense of affordability. When the repayment period begins, a $60,000 balance converts from interest-only (~$375/month at 7.5%) to fully amortizing (~$593/month over 10 years) — a $218/month increase with no change in lifestyle. Foreclosure risk: the lender can foreclose if you default, since the HELOC is secured by your home.
HELOC vs. home equity loan — choosing the right structure
Use a HELOC when costs are ongoing or variable, when you value flexibility, or when you may not need the full approved amount. Use a home equity loan when you need a known lump sum at a fixed rate — a specific renovation cost, a debt consolidation payoff, or a one-time major purchase. The fixed rate of a home equity loan provides payment certainty that HELOCs cannot, which is valuable when rates are rising or when budgeting precision matters.