How the Prime Rate Controls Your HELOC Payment

The prime rate is 6.75%. It has been since December 2025, and every variable-rate HELOC in America is priced off it. That single number determines your payment. Not your lender’s advertising. Not the national average you read about. Your rate is prime plus a margin your lender set at closing — and once you know your margin, you can calculate your own rate any time, and predict exactly what happens when the Federal Reserve moves.

Most homeowners with a HELOC have never been told this. After nearly thirty years in mortgage lending, I’ve found it’s the single most useful thing a variable-rate borrower can understand about their own loan.

What Is the Prime Rate?

The Wall Street Journal Prime Rate is the benchmark commercial banks use for their most creditworthy customers. It isn’t set by the Federal Reserve, and it isn’t set by any single bank.

The Wall Street Journal surveys the 30 largest U.S. banks and publishes a rate reflecting what they charge. The published figure changes when at least three-quarters of those banks adjust their posted rates. HSH Associates describes it as the base rate on corporate loans posted by at least 70% of the ten largest U.S. banks.

That survey mechanism matters. Prime doesn’t drift daily like mortgage rates. It sits at one number for months, then moves in a single step — usually within a day or two of a Federal Reserve decision.

A definitional note worth knowing: despite the name, prime isn’t the best rate available. Individual banks can and do declare their own prime rates, and some lenders offer HELOCs priced below the published figure. If your loan documents reference “the prime rate” without specifying the WSJ index, ask which one your lender uses.

The 300 Basis Point Rule

Here’s the mechanism that lets you predict prime before the Journal publishes it.

Prime sits 300 basis points — three percentage points — above the upper bound of the Federal Reserve’s federal funds target range.

Run it for today:

That relationship has held with remarkable consistency since the mid-1990s. It’s a convention rather than a law, but banks follow it closely enough that you can treat it as reliable.

What this gives you: when the Fed announces a decision, you don’t have to wait for anyone to tell you what happened to your HELOC. A quarter-point cut takes prime to 6.50%. A quarter-point hike takes it to 7.00%. Your rate follows within one to two billing cycles.

How to Calculate Your Own HELOC Rate

Your HELOC rate is a simple sum:

Your Rate = Prime Rate + Your Margin

The margin is the number your lender assigned at closing based on your credit score, combined loan-to-value ratio, line size, and any relationship discounts. It is fixed for the life of your line. Prime moves; your margin doesn’t.

To find your margin, subtract prime from your current rate.

If your statement shows 7.43%, your margin is 0.68% — that’s 7.43% minus 6.75%. If it shows 8.25%, your margin is 1.50%.

For context, the national average HELOC rate is 7.43% as of July 22, 2026, per Bankrate’s survey of the ten largest banks and thrifts, implying a typical margin near 0.68 points. Borrowers with stronger profiles do better — Curinos reports 7.23% for applicants above 780 FICO at under 70% CLTV, a margin of roughly 0.48.

Once you know your margin, you know your rate forever. Prime goes to 7.00%? Your rate is 7.68%. Prime drops to 6.25%? You’re at 6.93%. No calling your servicer, no waiting for a statement.

Some borrowers carry a negative margin. Promotional pricing at prime minus a fraction does exist — I’ve covered prime minus 1 HELOC offers separately, and the reversion terms deserve close reading before you sign.

What a Fed Move Actually Costs You

Here’s the number to memorize:

Each 0.25% change in prime moves your payment by roughly $10.42 per month for every $50,000 you have drawn.

The arithmetic is straightforward — $50,000 × 0.0025 ÷ 12 = $10.42.

Two things this table clarifies.

First, a single Fed move is manageable for most borrowers. Second, a sustained cycle is not. Between 2022 and 2023, prime rose from 3.25% to 8.50% — 525 basis points. A borrower carrying $150,000 saw their interest-only payment rise by roughly $656 a month over that stretch. That’s the risk variable-rate borrowers accept.

Note that this applies to the drawn balance only. An unused credit line costs you nothing when rates move.

Where the Prime Rate Stands and Where It’s Headed

The Federal Reserve has held its benchmark at 3.50%–3.75% through five consecutive meetings, most recently on July 29, 2026. Prime has sat at 6.75% throughout.

But that meeting told us something important. The vote was 9–3, and all three dissenters wanted to raise rates — Beth Hammack of Cleveland, Neel Kashkari of Minneapolis, and Lorie Logan of Dallas. It was the first time since September 2016 that three policymakers dissented with a unified view of direction.

Markets now price two quarter-point increases before year-end, and the Fed’s June Summary of Economic Projections put the 2026 year-end funds rate between 3.6% and 4.1% — revised upward from a prior estimate of 3.25% to 3.75%.

What that means for a HELOC borrower: the easing cycle that ran through late 2025 is over. Prime is more likely to rise than fall over the next several meetings. If you’re carrying a large drawn balance, the table above tells you what each move costs — and the case for paying down principal or converting to a fixed structure is stronger than it was a year ago.

The next FOMC decision comes September 15–16. Chair Kevin Warsh speaks at Jackson Hole in late August, which will likely signal more than any data release between now and then.

Caps and Floors: The Limits in Your Agreement

Every HELOC agreement contains boundaries that cap how far your rate can move.

Lifetime caps typically sit at 18%, though I’ve seen 17.5% and 21%. Federal law requires that variable-rate home equity plans disclose a maximum rate — check your agreement, because the cap is the ceiling on your risk.

Rate floors commonly run 2.25% to 4.00%, preventing your rate from falling below a minimum even if the formula calculates lower.

Right now, floors are nowhere near binding. With prime at 6.75% and a typical margin, a borrower would need prime to fall to roughly 3.50% before a 4.00% floor engaged — that’s thirteen consecutive quarter-point cuts. Given that the Fed’s own committee is voting for increases, floors are a theoretical concern rather than a practical one.

Some agreements also carry periodic caps, commonly 2% per year, limiting how fast your rate can climb in any twelve-month stretch. That’s a meaningful protection in a rising cycle, and it’s worth confirming whether yours has one.

Why Fixed Home Equity Loans Don’t Follow Prime

This trips people up constantly, so let me be explicit.

Fixed-rate home equity loans do not track the prime rate. They price off longer-term Treasury yields plus a lender margin, and once you close, your rate never changes regardless of what the Fed does.

That’s why the two products can move in opposite directions. Prime responds to short-term Fed policy; fixed home equity rates respond to the bond market’s view of inflation and growth over a decade or more. A Fed hike raises HELOC rates immediately and may barely touch fixed home equity pricing.

For a full comparison of the two structures, see our guide to HELOCs versus home equity loans.

One practical implication: if rate certainty matters to you and prime is likely to rise, many lenders allow you to convert part or all of a HELOC balance to a fixed rate mid-draw. Ask what that conversion costs and how many conversions your agreement permits.

What I’d Tell Any HELOC Borrower

Find your margin. It’s on your original disclosure or one phone call away. Once you have it, you control the information — you can calculate your rate the moment the Fed announces, without waiting for a statement.

Know what a move costs you. Multiply your drawn balance by 0.0025 and divide by twelve. That’s your exposure per quarter point.

Understand that the draw period ends. Prime governs your rate; it doesn’t govern your payment structure. When your interest-only draw period closes, your payment rises on amortization alone — often substantially. Our breakdown of interest-only HELOC repayment shows what that transition looks like across balance sizes.

And take the current environment seriously. Three Federal Reserve officials voted to raise rates last month. That’s not a forecast — it’s a recorded vote. A variable-rate borrower who understands the mechanism can plan around it. One who doesn’t will simply find out when the statement arrives.

This article reflects the author’s editorial analysis and is not individualized financial advice. Rates and Federal Reserve policy change frequently. Consult your loan agreement and a licensed mortgage professional regarding your specific situation. RefiGuide.org is an advertising marketplace, not a lender.

References

• Bankrate. (2026). Wall Street Journal prime rate index. 
• Board of Governors of the Federal Reserve System. (2026, July 29). Federal Reserve issues FOMC statement. 
• Cox, J. (2026, July 29). Fed rate decision July 2026: Divided Fed holds interest rates steady. CNBC.