HELOC Calculator
Work out how much a home equity line of credit can give you, and what it costs. See the credit available under your lender’s combined loan-to-value limit, the interest-only payment while you draw, the payment once repayment starts, and the total interest.
How to Use
- Enter what your home is worth and what you still owe on the mortgage.
- Enter the combined loan-to-value limit from your lender’s offer. Lenders set their own limit, so the 85% filled in is only an example.
- Enter how much you plan to draw, the HELOC rate, and the lengths of the draw period and the repayment period.
- Read the credit available, the interest-only payment during the draw, the payment once repayment starts, and the total interest.
- Check the table for the payments if the variable rate rises 1 or 2 points, and open the schedule to see every month.
Worked Example
How big is the line? A home worth $500,000 with $250,000 left on the mortgage, at a lender whose combined loan-to-value limit is 85%: the mortgage and the line together may reach $500,000 × 0.85 = $425,000, so the line can be up to $425,000 − $250,000 = $175,000.
What drawing $60,000 costs. At 8.5% the draw-period payment is $60,000 × 0.085 ÷ 12 = $425.00 a month, interest only, for 10 years — $51,000.00 of interest, with the whole $60,000 still owed at the end. Repayment then runs 20 years: with r = 0.085 ÷ 12 = 0.00708333 and n = 240, M = 60,000 × 0.00708333 × 1.00708333²⁴⁰ ÷ (1.00708333²⁴⁰ − 1) = $520.69 a month, adding $64,966.55 of interest. Total interest: $115,966.55.
The common mistake: budgeting on the draw-period payment. The $425.00 is not the payment for the life of the line. In month 121 it becomes $520.69, and if the rate has risen 2 points by then it is $599.03 — 41% more than the $425.00 you got used to. The interest-only years also add $51,000.00 of interest while the balance does not fall at all.
Show Work
Formulas
How a Home Equity Line Works
A home equity line of credit is a revolving loan secured by your house, like a credit card with the home as collateral. During the draw period you borrow what you need, up to the limit, repay and borrow again; many lines ask only for interest in those years. When the draw period ends the line closes to new borrowing and the repayment period begins, with payments that cover principal as well. Because the house secures the debt, falling behind can put it at risk — a reason to plan for the higher repayment payment from the start.
Home equity lending grew quickly in the United States after the Tax Reform Act of 1986 phased out the deduction for interest on consumer debt such as car loans and credit cards, while interest on loans secured by a home stayed deductible. The rules on deducting HELOC interest have changed since, so check the current position with a tax adviser before counting on it. Most lines carry a variable rate, set as an index — usually the prime rate — plus a margin, so the payment moves with interest rates.
About This Tool
This calculator works out the credit a home equity line can offer under the combined loan-to-value limit you enter, then prices a draw: interest-only payments through the draw period and a level payment that clears the balance over the repayment period. The bar shows how your home’s value divides into the mortgage, your draw, the rest of the line and the equity the lender will not lend against; the chart shows the payment step when repayment starts, at your rate and 1 and 2 points higher. The schedule lists every month with a CSV download. It assumes the whole amount is drawn at once and the rate stays level, so a real line with several draws and a moving rate will differ.
Everything runs in your browser; nothing you enter is sent anywhere.
Estimates for planning and education — not financial, tax or legal advice.
Related tools: Loan Calculator, Debt Consolidation Calculator, and Refinance Calculator.
Frequently Asked Questions
How much can I borrow with a HELOC?
Lenders cap the mortgage and the line together at a percentage of the home’s value, called the combined loan-to-value (CLTV) limit, and each lender sets its own. On a $500,000 home with a $250,000 mortgage and an 85% limit, the cap is $425,000, so the line can be up to $425,000 − $250,000 = $175,000. At an 80% limit it would be $150,000.
How is the payment worked out during the draw period?
If your line lets you pay interest only, the payment is the balance × the rate ÷ 12. Drawing $60,000 at 8.5% costs $60,000 × 0.085 ÷ 12 = $425.00 a month, and after ten years you still owe the full $60,000. Some lines require principal too, so check your agreement.
What happens when the draw period ends?
The balance is repaid with level payments of principal and interest. The $60,000 at 8.5% over 20 years becomes $520.69 a month, 22.5% more than the $425.00 before. With a 5-year draw and a 15-year repayment, $100,000 at 8% jumps from $666.67 to $955.65, a 43.3% rise.
How much interest does a HELOC cost in total?
Drawing $60,000 at 8.5% and paying interest only for 10 years costs $51,000.00, and repaying it over the next 20 years adds $64,966.55, for $115,966.55 in all. Paying principal during the draw period, or drawing only what you need when you need it, lowers that total.
What if the variable rate goes up?
HELOC rates usually float with an index such as the prime rate. If the rate on the $60,000 line were 2 points higher, at 10.5%, the payments would be $525.00 and then $599.03, and the total interest $146,766.70 — $30,800.15 more. The table under the chart shows +1 and +2 points for your own numbers.
How do I use the HELOC Calculator?
Just type your numbers. The answer shows up right away — there is no button to press. Change anything and it updates by itself.
Is it free? Does it work without internet?
Yes to both. It is free with no sign-up, and once the page has loaded it keeps working even with no internet.
Where does my data go?
Nowhere — every calculation runs on your own device. Nothing you enter is uploaded, logged, or stored.
Common Use Cases
Paying for a remodel
A $75,000 kitchen on a $400,000 home with $180,000 owed fits easily in the $160,000 line at 85%; at 8.25% it is $515.63 a month, then $639.05.
Using the full line
Drawing all $150,000 available on a $500,000 home at an 80% limit costs $1,062.50 a month interest-only and $1,301.73 once repayment starts.
Checking thin equity
With $290,000 owed on a $350,000 home, an 85% limit leaves only $7,500 to borrow — about $56.25 a month at 9%.
Planning for the payment jump
A 5-year draw on $100,000 at 8% means $666.67 a month, then $955.65 for 15 years — $288.98 more to budget for.
Stress-testing the rate
Two points higher, the $60,000 line at 8.5% costs $599.03 a month in repayment instead of $520.69.
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