HELOC Calculator
A home equity line of credit (HELOC) lets you borrow against your home. Most lenders cap it at about 80% to 85% of your home’s value, minus what you still owe.
Updated · Estimates only, not financial advice
Estimate your HELOC
Result
This is an estimate, not a loan offer. Your actual credit line depends on an appraisal, your credit, your income and the lender’s rules. Most HELOC rates are variable, so payments can rise or fall. It assumes you borrow the full amount at the start and the rate stays the same. This is general information, not financial advice. A HELOC is secured by your home, which you could lose if you can’t repay.
Quick answer
Your estimated HELOC limit = home value × the lender’s combined loan-to-value (CLTV) limit − your mortgage balance. For a $400,000 home with $250,000 owing and an 85% limit, that’s $400,000 × 0.85 − $250,000 = $90,000. Borrowing $50,000 at 8.5% costs about $354.17 a month in interest only during a 10-year draw period, then about $433.91 a month over a 20-year repayment period.
How to use the HELOC calculator
- Enter your home’s estimated value and how much you still owe on your mortgage.
- Enter the lender’s borrowing limit (CLTV) and the interest rate they quote.
- Optionally, enter how much you plan to borrow and the draw and repayment periods.
- Press Calculate to see your estimated credit line and monthly payments in both periods.
HELOC formulas
Credit line = home value × CLTV − mortgage balance
Draw-period payment (interest only) = amount borrowed × rate ÷ 12
Repayment payment = amount × r ÷ (1 − (1 + r)−n)
In the repayment formula, r is the yearly rate ÷ 12 and n is the number of monthly payments in the repayment period.
Worked example
$400,000 home, $250,000 owing, 85% limit, $50,000 borrowed at 8.5%
Credit line: $400,000 × 0.85 − $250,000 = $90,000. Interest-only payment during a 10-year draw: $50,000 × 0.085 ÷ 12 = $354.17 a month. Over a 20-year repayment period the payment rises to $433.91 a month. Total interest over 30 years is about $96,638.79.
Watch for the jump in payments
During the draw period, many HELOCs only require interest payments, which keeps them low. When the repayment period starts, you begin paying back the principal too, so the monthly payment can rise sharply. In the example above it goes up by about $80 a month, and by more if rates have risen. Plan for the repayment payment, not just the draw-period one.
HELOC vs. home equity loan
A home equity loan gives you a lump sum at a fixed rate with steady payments. A HELOC works more like a credit card: you borrow what you need, when you need it, usually at a variable rate. A HELOC suits ongoing costs, such as a renovation paid in stages. A home equity loan suits one known cost.
When you’d actually use a HELOC calculator
- Planning a renovation. See how much you could borrow, and what the payments look like before and after the draw period ends.
- Comparing with a personal loan. Weigh a lower HELOC rate against the risk of borrowing against your home.
- Stress-testing a rate rise. Try the same amount at a rate 2% higher to see how much payments could grow.
How we calculate
The credit line is your home value times the CLTV limit, minus your mortgage balance, and can’t go below zero. We assume you borrow the full amount at the start of the draw period, make interest-only payments during it, and then repay the balance in equal monthly payments over the repayment period at the same rate. Real HELOCs often have variable rates, minimum draws, fees and different payment rules, so check your lender’s terms. Figures are rounded to the cent for display.
Frequently asked questions
How much can I borrow with a HELOC?
Lenders usually let your total home debt reach 80% to 85% of your home's value. Your credit line is roughly home value × that limit − what you owe. A $400,000 home with $250,000 owing at an 85% limit gives about $90,000.
What is CLTV?
Combined loan-to-value (CLTV) is everything you owe on your home, including the new HELOC, divided by the home's value. A lender with an 85% CLTV limit won't let your total debt go above 85% of the value.
How are HELOC payments calculated?
During the draw period, many HELOCs only require interest: balance × rate ÷ 12. In the repayment period you pay principal and interest, like a regular loan, so the payment rises.
Are HELOC rates fixed or variable?
Most HELOC rates are variable and move with the prime rate, so your payment can change. Some lenders let you fix the rate on part of your balance.
What is the difference between a HELOC and a home equity loan?
A home equity loan is a lump sum with a fixed rate and payment. A HELOC is a revolving line you draw from as needed, usually at a variable rate.
Is HELOC interest tax deductible?
In the US, HELOC interest may be deductible if the money is used to buy, build or substantially improve the home that secures it, and you itemize. Check IRS rules or a tax professional for your situation.