Home equity calculator
HELOC payment calculator: how much is the payment on a $100,000 HELOC?
Enter your balance and a rate, and see the interest-only payment and the principal-and-interest payment side by side. The math is simpler than it looks.
On an interest-only HELOC, the monthly payment is your balance times the rate, divided by 12. So every 1 percentage point on $100,000 is about $83 a month, and you multiply $83 by your rate to get the payment, or plug your own numbers into the calculator below.
Once the draw period ends, the payment adds principal, and I show that math too. For how I shop the line itself, see my page on HELOC options in Orange County. If you're weighing a line against refinancing, HELOC vs. cash-out refinance covers that.
The calculator
Enter the balance you plan to draw and a rate. Use the rate from an actual quote if you have one. The results are an illustration, not an offer.
Illustration only, using the balance and rate you enter, with the rate held constant. Not an offer, a quote or a commitment to lend. Your actual rate, APR, fees, draw and repayment terms come from a lender’s disclosures. Equal Housing Lender.
A real quote comes with an APR, not just a rate, plus any annual fee, draw minimum and closing costs. Compare quotes on APR and costs, not the headline rate alone.
The interest-only formula
Monthly interest = balance drawn × annual rate ÷ 12
That's it. Two things people miss:
- You pay on what you've drawn, not the full line. A $200,000 line with $30,000 drawn has a payment based on $30,000.
- The rate usually floats. Most HELOCs track the prime rate plus a margin. When prime moves, your payment moves the next cycle.
Interest cost per 1 percentage point
This is the shortcut I use on the phone. Multiply the number in the table by your rate.
| Balance drawn | Monthly interest per 1 percentage point |
|---|---|
| $50,000 | $41.67 |
| $100,000 | $83.33 |
| $250,000 | $208.33 |
The same table tells you what a rate change costs. If your HELOC rate goes up half a point on a $250,000 balance, that's about $104 more a month.
The repayment formula, in words
When the draw period ends, the balance gets paid off over a set term, often 20 years. The payment is now fully amortized. That means one level payment each month that covers that month's interest and chips away at principal, sized so the last payment brings the balance to zero.
The formula is the same one used for a car loan or a 30-year mortgage. In words:
- Take the monthly rate (the annual rate divided by 12).
- Take the number of months in the repayment period.
- The payment is the balance times the monthly rate, divided by one minus (one plus the monthly rate) raised to the negative number of months.
The calculator does that for you. Two easy checks you can do in your head:
- Principal averages the balance divided by the months. $100,000 over 240 months is about $417 a month of principal on average. $50,000 is about $208. $250,000 is about $1,042.
- The early payments lean toward interest. In month one of repayment, the interest piece is about the same as your old interest-only payment. The principal piece starts small and grows.
What happens at that switch, and how to get ahead of it, is in what happens when your HELOC draw period ends.
Three examples, no rates
Illustrations only. Swap in your own rate.
$50,000 for a kitchen. Interest-only, the payment is $41.67 times your rate. You draw in stages as the contractor bills, so the balance, and the payment, ramps up over a few months instead of starting at $50,000.
$100,000 to pay off debt. Interest-only, $83.33 times your rate. The risk here isn't the math, it's the habit. If the cards go back up, you've moved debt onto your house without getting rid of it. I'll only set this up with a real payoff plan.
$250,000 for an ADU. Interest-only, $208.33 times your rate. In repayment over 20 years, principal averages about $1,042 a month on top of interest. On a project this size I usually run a HELOC and a cash-out refinance side by side, because the answer depends on your first mortgage rate. See ADU financing in Orange County.
Why I use the per-point shortcut
At Chase I watched clients stare at amortization tables and tune out. What stuck was one number: what a point of rate costs them a month. It works both ways. It tells you what you'll pay, and it tells you what's at stake if rates rise 2 points during a ten-year draw period.
On $100,000, a 2-point rise is about $167 a month. If that would break your budget, draw less, pay it down faster, or look at locking a fixed rate on part of the balance.
Paying principal during the draw period
Interest-only is the minimum on many lines, not the rule. You can usually pay principal any time during the draw, and every dollar you pay down cuts next month's interest.
Here's a simple way to think about it. Pick the payoff date you want, then divide. If you draw $60,000 and want it gone in five years, that's $1,000 a month of principal on top of interest. The interest part then shrinks every month, because the balance does.
People who do this rarely feel the jump when the draw period ends. There's less balance left to amortize, so the repayment payment is smaller. People who pay only interest for ten years are the ones who get surprised.
Line size vs. balance
The calculator works on the balance, not the line. That's worth repeating, because it changes how you size a line.
A bigger line doesn't cost more in interest if you don't use it. It can cost more in other ways: some lenders charge an annual fee, and a larger line counts against your available credit and, with some lenders, your debt ratio. My rule of thumb is to size the line to the real project plus a cushion, not to the maximum the house allows.
What the calculator can't tell you
- Your actual rate. That depends on credit, CLTV, the lender, the line size and the property.
- Fees. Some lines have annual fees, draw fees or early-closure fees.
- Whether a HELOC is the right loan. If your first mortgage rate is already near the market, a single refinance can come out ahead.
That's the part I do. I pull quotes from multiple lenders, each with its APR and costs, and put them on one page so you're comparing real numbers.
Questions people ask
How much would a monthly payment be on a $100,000 HELOC?
During an interest-only draw period, the payment is the balance times the rate, divided by 12. Every 1 percentage point on $100,000 is about $83 a month, so multiply $83 by your rate. Once repayment starts, you also pay principal, which averages about $417 a month on $100,000 over 20 years. Use the calculator on this page with the rate from your own quote.
What is the payment on a $50,000 HELOC?
Interest-only, it's about $41.67 a month for every 1 percentage point of rate. Multiply that by your rate. In repayment over 20 years, principal adds roughly $208 a month on average.
How is an interest-only HELOC payment calculated?
Balance drawn, times the annual rate, divided by 12. You only pay interest on what you've actually drawn, not on the full line. If you have a $150,000 line and $40,000 drawn, the payment is based on $40,000.
Do HELOC payments change?
Usually, yes. Most HELOCs have a variable rate tied to the prime rate, so the payment moves when rates move. It also changes when you draw more or pay down the balance, and it changes when the draw period ends and principal payments begin.
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