About the HELOC Calculator
A home equity line of credit, or HELOC, lets you borrow against the equity in your home as you need it, up to a limit. Lenders usually allow total borrowing, your mortgage plus the line, of 80 to 90 percent of the home's value. This calculator works that out: it takes your home value, your mortgage balance and the lender's limit, and shows the equity you have and the largest line you could be offered. If you enter an amount you plan to draw and a rate, it also estimates the interest-only payment during the draw period and the full payment during the repayment period, when you pay back principal and interest.
Updated October 2026
How to use the HELOC Calculator
- 1Enter your home's value and your mortgage balance.
- 2Enter the lender's limit on total borrowing as a percentage of value.
- 3Read the equity and the possible credit line.
- 4Optional: enter the amount you plan to draw, the rate and the repayment years.
- 5Check the interest-only and repayment payments.
Worked example
Take a 400,000 home with a 250,000 mortgage. An 85 percent combined limit allows 340,000 of total debt, so the possible line is 90,000, and your equity is 150,000. If you draw 40,000 at 8.5 percent, the interest-only payment is about 283 a month. Repaying that balance over 15 years later would cost about 394 a month, with around 30,900 of interest in total.
If you are thinking about a HELOC to fund a renovation, get quotes from contractors first so you borrow only what you need, and compare the line with a fixed-rate home equity loan, which gives a single payment you can plan around. Ask lenders about annual fees, early-closure charges, minimum draws and whether the rate has a cap, since those terms differ a lot and can change the cost of the line over its life.
Good uses and bad uses
- Good: home improvements that add value.
- Good: consolidating high-interest debt, if you don't run it up again.
- Good: a short-term bridge you can repay soon.
- Risky: everyday spending or holidays.
- Risky: investing borrowed money.
What lenders look at
Besides equity, lenders check your credit score, income and existing debts. A score of about 680 or more helps, and a debt-to-income ratio under 43 percent is common. They may order an appraisal to confirm your home's value, which can differ from your own estimate or from online tools.
Related tools
The Home Equity Loan Calculator covers the fixed lump-sum version, the Mortgage Calculator and Refinance Calculator model your main loan, the Debt-to-Income Calculator tests the ratio lenders use and the Loan-to-Value Calculator shows your ratio on its own.
Features
- Equity and available line
- Combined loan-to-value limit
- Interest-only payment during the draw period
- Payment during repayment
- Total repayment interest
- Clear error if the draw exceeds the line
Frequently asked questions
How much can I borrow with a HELOC?
Multiply your home's value by the lender's limit, subtract your mortgage balance and the rest is the maximum line. With a 400,000 home, a 250,000 mortgage and an 85 percent limit, that is 340,000 minus 250,000, or 90,000.
What is combined loan-to-value?
The total of all loans secured on your home divided by its value. Lenders cap it, typically at 80 to 90 percent, so there is always some equity left as a cushion.
How do HELOC payments work?
During the draw period, often 10 years, you can borrow and repay as needed and usually pay interest only on what you have used. After that, the repayment period begins, often 10 to 20 years, and you pay principal and interest on the balance.
Are HELOC rates fixed?
Most are variable, tied to a benchmark rate such as the prime rate, so payments can rise. Some lenders offer a fixed-rate option on part of the balance. The calculator uses one rate for the whole period.
Is HELOC interest tax deductible?
In some countries, interest may be deductible when the money is used to buy, build or substantially improve the home, but rules vary and change. Ask a tax professional about your situation.
What are the risks?
Your home secures the line. If you can't make payments, the lender can foreclose. Falling home prices can also reduce your line or lead to a freeze. Borrow only what you can repay.