"Should I use a HELOC or roll the money into a refinance?" is usually answered with generalities. Here's the same question answered with one concrete scenario, both payment schedules computed in full, and the exact rate where the two options stop being different.
You need $50,000 for a renovation. Your home is worth $400,000 with a $350,000 mortgage outstanding at 6.5% with 30 years remaining. You're considering two paths:
Both are legitimate. The difference is where the $50k sits in your financial life — and that changes the math more than the headline rate.
| Term | Monthly payment | Total interest (10 yr) | Total repaid |
|---|---|---|---|
| $50,000 @ 8%, 120 months | $606.64 | $22,797 | $72,797 |
Two things about this number. First, the 10-year amortization is doing real work: a pure interest-only HELOC at 8% would be $333/mo, but you'd be paying $22,797 in interest forever without ever reducing principal. Second, HELOCs are usually variable-rate — the 8% is a starting point. Every 0.5% the prime index climbs, your payment rises roughly $16/mo on this balance.
| Old loan (350k @ 6.5%, 30 yr) | New loan (380k @ 6.8%, 30 yr) | Delta | |
|---|---|---|---|
| Monthly payment | $2,212.24 | $2,477.32 | +$265.08 |
The refinance costs you $265.08/mo in perpetuity (for the life of the 30-year loan). Over the first 10 years — the same window as the HELOC — that's $31,810. Add the $1,900 closing cost and the total 10-year price of the refinance is roughly $33,710.
HELOC: $22,797 interest · Refinance: $33,710 (interest premium + closing). On this timeline, the HELOC wins by about $10,900.
But the refinance has a structural advantage the table doesn't show: one payment instead of two, and the $50k sits in a 30-year amortization. If you pay the HELOC off early — say in year 3 — you stop paying the 8% entirely while keeping your mortgage rate. The refinance, by contrast, locks the $50k into 6.8% for 30 years whether you want it or not.
There's a HELOC rate above which the refinance becomes the cheaper 10-year option. Working the two payment schedules against each other, that rate is 10.75%. Below it, the HELOC wins on interest. Above it, the lower refinance rate dominates. Most HELOC pricing sits in the 7–11% band depending on the prime index, so this is a genuinely live decision, not a theoretical one.
The break-even assumes you hold the HELOC for the full 10 years. If you plan to pay it off early, the effective break-even drops — the HELOC becomes cheaper faster the sooner you retire it.
Choose the HELOC if: you plan to pay it off within 3–5 years, your income is stable enough to carry two payments, and the starting rate is under 10%. You get the lower total cost and the optionality to exit early.
Choose the refinance if: you want one payment, you expect to hold the $50k for more than 10 years, you itemize deductions and the money is home-related, or your HELOC quote is above 10.75%. You pay more in interest but buy simplicity and rate certainty.
Run your own numbers with our HELOC Calculator — it takes your actual balance, rate, and term and outputs the payment and total interest before you commit.
CalcClear.com provides educational tools and general information. Nothing on this site is financial, lending, or tax advice. Rates and terms in this guide are illustrative. Lending terms, qualification requirements, and tax treatment vary by lender, state, and individual circumstance. Consult a qualified professional before making lending decisions.