HELOC Calculator
This HELOC calculator shows how large a home equity line of credit could be and what a draw would cost each month. Example: a home worth $400,000 with $250,000 still owed and an 80% limit leaves a credit line of $70,000. Drawing $50,000 at 8% costs $333.33 a month while only interest is due, and $418.22 a month once the 20-year repayment period starts.
How it is calculated
A home equity line of credit (HELOC) lets you borrow against the part of your home you already own. Two questions decide whether it fits: how much a lender would make available, and what the payments look like – first while you draw, then while you repay. This page calculates both from your own figures.
How the credit line is calculated
Lenders limit the total of all loans secured by the home to a share of its value, the combined loan-to-value ratio (CLTV). Credit line = home value × CLTV limit − mortgage balance. With $400,000, 80% and $250,000: $320,000 − $250,000 = $70,000. The same home with an 85% limit would allow $90,000. The limit differs from lender to lender, and credit score and income also play a part, so enter the figure your lender quotes.
Draw period and repayment period
During the draw period you can borrow, repay and borrow again, and many plans only ask for interest: balance × rate ÷ 12. When the draw period ends you can no longer borrow, and the balance is paid off in level payments over the repayment period – or, in some plans, is due all at once. The step up is noticeable because principal is now included.
Worked example
Drawing $50,000 at 8%: $50,000 × 0.08 ÷ 12 = $333.33 a month for 10 years, $40,000.00 of interest in total, and the balance is still $50,000. In the 20-year repayment period the payment is $418.22 a month, with another $50,372.81 of interest. Altogether: $90,372.81 of interest, $140,372.81 repaid.
What a rate change does
Most HELOC rates move with a benchmark such as the prime rate. One percentage point more (9%) raises the interest-only payment to $375.00 and the repayment-period payment to $449.86; at 10% they are $416.67 and $482.51. The scenario table shows these three rates for your own figures.
What is left out
Closing costs, annual fees, minimum draw amounts, rate caps and early-termination charges are not included, and neither is tax treatment. Paying principal during the draw period lowers both the interest and the later payment.
Frequently asked questions
How much HELOC can I get?
Multiply your home value by the lender’s CLTV limit and subtract what you still owe. A $400,000 home with an 80% limit and a $250,000 mortgage gives $70,000. Approval also depends on your credit and income.
What is the monthly payment on a $50,000 HELOC?
At 8% the interest-only payment is $333.33 a month. Once repayment starts, a 20-year period means $418.22 a month. At 9% the two figures are $375.00 and $449.86.
What is CLTV?
Combined loan-to-value: all loans secured by the home divided by its value. In the example, a $250,000 mortgage plus a $50,000 draw on a $400,000 home is 75%.
What happens when the draw period ends?
You can no longer borrow from the line. Depending on the plan, the balance is repaid in monthly instalments over a set period, or it is due in full as a balloon payment. Your agreement says which applies.
Is a HELOC rate fixed or variable?
Usually variable: it follows an index plus a margin, so the payment can change during both periods. Some lenders let you fix the rate on part of the balance. The scenario table shows the effect of one and two percentage points more.
How is a HELOC different from a home equity loan?
A home equity loan pays out one lump sum with fixed payments from the start. A HELOC is a revolving line: you borrow what you need during the draw period and pay interest only on what you have drawn.
Sources and legal basis
- Consumer Financial Protection Bureau: Mortgage key terms – Home equity line of credit (HELOC): home equity, variable interest rate, “draw period” and subsequent repayment (retrieved 5 Oct 2026)
- 12 CFR § 1026.40: Consumer Financial Protection Bureau: What you should know about home equity lines of credit (HELOC) – brochure under Regulation Z
- Consumer Financial Protection Bureau: What is a loan-to-value ratio and how does it relate to my costs?
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