HELOC Calculator
This HELOC calculator estimates how much home equity you could borrow against, and what a home equity line of credit actually costs across its two phases: interest-only payments during the draw period, then full repayment afterward. Enter your home's value, existing mortgage, and draw amount to see both.
Your home's current estimated market value.
What you still owe on your primary mortgage.
How much of your available equity you plan to actually borrow.
Typically variable, tied to the prime rate.
Years you can borrow and make interest-only payments before repayment begins.
Years to fully repay the drawn balance after the draw period ends.
Maximum available to borrow
$120,000
An estimate based on an 85% combined loan-to-value cap, common among HELOC lenders.
How to use this heloc calculator
- 1Home value and existing mortgage balance: used to estimate your maximum available credit line.
- 2Amount you want to draw: how much you actually plan to borrow, which may be less than your maximum.
- 3Draw period and repayment period: check your HELOC offer for these — commonly 10 years draw, 15-20 years repayment.
Understanding your results
Maximum available to borrow is an estimate using an 85% combined loan-to-value cap — a common (though not universal) lender limit meaning your mortgage plus HELOC can't exceed 85% of your home's value. The interest-only payment during the draw period is often surprisingly low since you're not paying down principal yet; the repayment-period payment jumps up because it now has to cover both principal and interest over a shorter window.
The formula
Draw period payment = Balance × Rate ÷ 12 · Repayment period = standard amortizing loanDuring the draw period, most HELOCs only require interest on the amount actually drawn, so the payment is simply the balance times the monthly rate — the principal doesn't shrink unless you voluntarily pay extra. Once the repayment period starts, the drawn balance converts to a standard amortizing loan over the repayment term, meaning the payment jumps to cover both principal and interest.
A worked example
A $400,000 home with a $220,000 existing mortgage has roughly $120,000 in available HELOC equity at an 85% cap. Drawing $50,000 at 9% APR costs about $375/month during a 10-year interest-only draw period — then jumps to roughly $507/month once the 15-year repayment period begins, since that payment now has to fully pay off the $50,000 balance.
Notes for the UK, US and India
HELOC rates are usually variable, tied to a benchmark like the prime rate, so your actual payment can rise or fall over the life of the line — this calculator assumes a constant rate for simplicity. The jump from interest-only to full repayment is the single most common HELOC surprise; budget for the repayment-period payment well before the draw period ends.
Frequently asked questions
What's the difference between a HELOC and a home equity loan?+
A HELOC is a revolving credit line you can draw from repeatedly during the draw period, with a variable rate. A home equity loan is a single lump sum with a fixed rate and fixed repayment schedule from day one — more like a second mortgage.
Can I pay down principal during the draw period?+
Yes, and it's usually a good idea if you can — any extra payment during the draw period reduces the balance the repayment-period payment will be calculated on, lowering that future payment.
Why is the 85% loan-to-value figure just an estimate?+
Actual limits vary by lender, your credit profile, and location — some lenders go up to 90% or cap it lower. Treat this as a planning estimate and confirm your real available line with a lender.
Related calculators
Related articles
Capital One Auto Finance Calculator: How to Figure Out Your Car Payment Before Shopping
Loans
Capital One Auto Payment Calculator: How to Figure Out Your True Car Loan Cost
Loans
HDFC Loan Calculator: How to Make Your EMI Actually Feel Manageable
Loans
ICICI FD Interest Rates: What Your Returns Actually Look Like (Without the Bank Jargon)
Loans