HELOC Calculator
Enter your home value, mortgage balance and the lender's CLTV limit to see how big a home equity line of credit you can get. Then see the interest-only payment during the draw period, the higher payment once repayment starts, and the total interest.
An appraisal or a recent comparable sale price.
All existing loans on the home. 0 if it is paid off.
Combined loan-to-value limit; usually 80% to 90%.
Leave empty to use the full credit line.
Usually variable: prime rate + a margin.
How to use the HELOC Calculator
- Enter your home value and the total you still owe on your mortgage.
- Set the lender's CLTV limit, commonly 80%, 85% or 90%, to see your available credit line.
- Enter how much you plan to draw, the HELOC rate and the draw and repayment periods.
- Compare the interest-only payment with the repayment-period payment and the total interest.
- Check the yearly schedule and download it as CSV if you want to keep it.
How the HELOC credit line is calculated
Lenders cap the total of all loans on your home at a percentage of its value, the combined loan-to-value (CLTV) limit. Your credit line is whatever room is left under that cap after your existing mortgage:
Credit line = Home value × CLTV limit − Mortgage balance
Example: a $450,000 home with a $260,000 mortgage at an 85% limit gives $450,000 × 0.85 − $260,000 = $122,500.
| CLTV limit | Max total borrowing ($450,000 home) | HELOC line with a $260,000 mortgage |
|---|---|---|
| 80% | $360,000 | $100,000 |
| 85% | $382,500 | $122,500 |
| 90% | $405,000 | $145,000 |
Draw period vs. repayment period payments
A HELOC usually has two phases. During the draw period (often 10 years) you can borrow, repay and borrow again, and many lenders only require interest-only payments: balance × annual rate ÷ 12. In the repayment period (often 20 years) you can no longer draw, and the balance is amortized with the standard loan formula M = P × r ÷ (1 − (1 + r)−n), where r is the monthly rate and n the number of months.
With $60,000 drawn at 8.25%, the interest-only payment is $412.50 a month, then $511.24 a month over a 20-year repayment period: a jump of about $98.74. Plan for that "payment shock" before the draw period ends.
| Rate | Interest-only on $50,000 | 15-year repayment | 20-year repayment |
|---|---|---|---|
| 7.0% | $291.67 | $449.41 | $387.65 |
| 8.0% | $333.33 | $477.83 | $418.22 |
| 9.0% | $375.00 | $507.13 | $449.86 |
| 10.0% | $416.67 | $537.30 | $482.51 |
This calculator assumes the full amount is drawn at the start and the rate stays fixed. Real HELOC rates are usually variable (prime rate + margin), so payments change when the prime rate moves. Some lenders also charge annual fees, closing costs or minimum draw amounts.
Frequently asked questions
How much HELOC can I get?
Most lenders let your mortgage plus the HELOC add up to 80% to 90% of your home's value (the CLTV limit). Multiply the home value by that percentage and subtract your mortgage balance. For a $450,000 home with a $260,000 mortgage and an 85% limit, that is $382,500 − $260,000 = $122,500. Your credit score, income and debt-to-income ratio can lower the amount you are approved for.
How is the interest-only HELOC payment calculated?
Multiply the amount you have drawn by the annual interest rate and divide by 12. A $60,000 balance at 8.25% costs $412.50 a month in interest. The payment does not reduce the balance, so you still owe the full amount when the draw period ends.
What happens when the HELOC draw period ends?
You can no longer borrow, and the remaining balance is paid off over the repayment period with principal and interest payments. That payment is usually much higher than the interest-only payment: $60,000 at 8.25% over 20 years is about $511 a month instead of $412.50.
Is a HELOC rate fixed or variable?
Most HELOCs have a variable rate tied to the prime rate plus a margin, so the payment changes when rates move. Some lenders let you lock part of the balance at a fixed rate. This calculator uses the rate you enter for the whole term, so try a higher rate to see how a rise would affect you.
What is the difference between LTV and CLTV?
Loan-to-value (LTV) compares one loan to the home value. Combined loan-to-value (CLTV) adds up every loan secured by the home, such as your first mortgage plus a HELOC or home equity loan. HELOC limits are set on CLTV.
Can I pay more than the interest-only minimum?
Usually yes. Paying principal during the draw period lowers the balance, the interest you pay and the jump in payment when repayment starts. Because the line is revolving, repaid amounts can normally be borrowed again until the draw period ends.
Are my numbers stored or sent anywhere?
No. The calculation runs entirely in your browser and nothing you enter is uploaded.