What this page sets up
The calculator opens with the comparison first: 75,000 of cash on a 450,000 home with 250,000 left on a 3% mortgage and 25 years to go. The HELOC row keeps that mortgage and adds a line at prime plus a margin, interest only for 10 years and then repaid over 20. The cash-out refinance row replaces both with one new loan at the current 30-year average, with 3% closing costs financed into it. The home equity loan row is there for a fixed-rate option on the new cash only. Type your own mortgage rate, years left and the quotes you have.
Reading the comparison
- Monthly now is everything you’d pay in the first month: the old mortgage plus the HELOC, or the one new loan.
- Highest monthly is the largest payment you’d face. For the HELOC that is usually when its repayment starts, so check you could afford it.
- Total interest and closing costs run until each option is fully paid, so they cover different lengths of time. The highlighted row costs the least in total; the notice under the table gives your blended rate.
When each one tends to win
The rate on your mortgage now decides most of it. The table below runs the same cash at a range of current mortgage rates: with a mortgage in the 3% to 5% range, keeping it and adding a HELOC costs far less in total, because a refinance would reprice the whole balance. As your current rate approaches the refinance rate, the refinance catches up, especially over the same years you have left. Two things the totals don’t show: a HELOC’s rate can rise, which the rate scenarios on the page let you test, and a refinance fixes the payment for good. The CFPB lists higher closing costs, a longer payoff and a rate that may be above your current mortgage as the usual downsides of a cash-out refinance.
For the full picture of a HELOC’s draw and repayment years, the HELOC calculator opens with borrowing power first.
Which costs less, by the rate on your mortgage now
$75,000 of cash on top of a $250,000 mortgage with 25 years left. The HELOC is at 7.50% (prime plus 0.5), interest only for 10 years and then repaid over 20; the cash-out refinance replaces the mortgage with a $335,052 loan at 7.03% (the Freddie Mac 30-year average for the week of September 24, 2026), with 3% closing costs financed. Totals are interest plus closing costs until each option is paid off.
| Mortgage rate now | Blended rate with HELOC | HELOC + mortgage: monthly now | HELOC + mortgage: total cost | Refi over 25 years: monthly | Refi over 25 years: total cost | Refi over 30 years: monthly | Refi over 30 years: total cost |
|---|---|---|---|---|---|---|---|
| 3% | 4.04% | $1,654.28 | $231,915 | $2,374.49 | $387,347 | $2,235.86 | $479,910 |
| 4% | 4.81% | $1,788.34 | $272,134 | $2,374.49 | $387,347 | $2,235.86 | $479,910 |
| 5% | 5.58% | $1,930.23 | $314,699 | $2,374.49 | $387,347 | $2,235.86 | $479,910 |
| 6% | 6.35% | $2,079.50 | $359,483 | $2,374.49 | $387,347 | $2,235.86 | $479,910 |
| 6.5% | 6.73% | $2,156.77 | $382,662 | $2,374.49 | $387,347 | $2,235.86 | $479,910 |
| 7% | 7.12% | $2,235.70 | $406,341 | $2,374.49 | $387,347 | $2,235.86 | $479,910 |
| 7.5% | 7.50% | $2,316.23 | $430,500 | $2,374.49 | $387,347 | $2,235.86 | $479,910 |
| 8% | 7.88% | $2,398.29 | $455,119 | $2,374.49 | $387,347 | $2,235.86 | $479,910 |
Bold marks the cheaper of the HELOC and a refinance over the same 25 years. The 30-year refinance has the lowest payment of the refinances but the highest total, because it restarts the clock. The HELOC's monthly figure is its interest-only payment; it rises when repayment starts in year 11, which the calculator shows as the highest monthly payment.
Worked out with the calculator's own engine, with required payments only and the HELOC rate held at today's. Sources: Freddie Mac Primary Mortgage Market Survey via FRED, 30-year fixed average; Federal Reserve H.15 via FRED, bank prime loan rate; CFPB, What you should know about home equity lines of credit; HUD, Mortgagee Letter 2019-11 (FHA cash-out at most 80% of the value); Fannie Mae, Eligibility Matrix, April 1, 2026 (conventional cash-out on a one-unit principal residence at most 80%). For planning, not financial advice.