What this page sets up
The calculator opens on the draw-period payment of an interest-only line: 100,000 drawn at prime plus 0.5, a 10-year draw period and 20 years of repayment. At US prime of 7.00% (as of October 20, 2026) that’s 7.5%, so the large figure reads 625.00 a month, with the 805.59 repayment payment under it. Enter your own balance, your margin from the agreement and the length of each period; the prime rate box updates the whole page if prime moves.
The two ways of paying, side by side
The first table under the results runs the same line twice:
- Interest only: 625.00 a month for 10 years. Nothing is repaid, so 100,000 is still owed when repayment starts, and the payment jumps by 180.59.
- Principal and interest: 699.21 a month from the start, and no jump at all, because the balance is already down to about 86,795 when the draw period ends.
The extra 74.21 a month in the draw period saves about 16,625 of interest over the 30 years. Switching Draw period payments in the form moves the highlight to the way you picked and updates the payments above.
Planning for the jump
The Payment shock line under the two payments is the number to plan around. Some ways to soften it:
- Pay a little principal anyway. The Extra payment each month box goes straight to principal; even 100 a month in the draw period lowers the balance repayment starts from.
- Check what the jump looks like if rates rise. The If the rate changes table below shows the draw and repayment payments with the rate 1 to 3 points higher, or 1 point lower.
- Read the repayment terms. The CFPB’s HELOC booklet warns that some plans end with the full balance due at once; if yours does, you’ll need to refinance or pay it off before the draw period ends.
Already in a HELOC and want to know when it’ll be paid off? The HELOC payoff page starts from the balance you owe now.
Source: Consumer Financial Protection Bureau, What you should know about home equity lines of credit; Federal Reserve H.15 for the prime rate.