Prime Rate vs. SOFR: How Benchmark Rates Affect Your Business Loan

Most business loans don't have a fixed rate that stays constant for the full term. They have a variable rate — usually expressed as a benchmark rate plus a spread. When the benchmark moves, your rate moves with it.

Understanding which benchmark rate your loan uses, how that rate is set, and what a rate change means for your payment is essential for any borrower with variable-rate debt.

The Prime Rate

The Prime Rate is the interest rate that major U.S. banks charge their most creditworthy customers. In practice, it's not individually set by each bank — it's published by the Wall Street Journal as a consensus rate and moves with the Federal Funds Rate.

How Prime is set:

• The Federal Reserve's Federal Open Market Committee (FOMC) sets the Federal Funds Rate at meetings throughout the year
• The Prime Rate moves in lockstep: traditionally, Prime = Federal Funds Rate + 3%
• When the Fed raises rates by 0.25%, Prime rises by 0.25%
• When the Fed cuts rates by 0.50%, Prime falls by 0.50%

How Prime affects your loan:

Most variable-rate small business loans are priced as Prime + a spread. The spread reflects the lender's risk assessment of the borrower — lower spread for stronger borrowers, higher spread for weaker ones.

Example: "Prime + 2.25%" on a loan originated when Prime was 8.5% = 10.75% total rate. If Prime drops to 7.5%, your rate drops to 9.75%. Your monthly payment changes accordingly.

Products commonly tied to Prime:

• SBA 7(a) loans (variable-rate option)
• Business lines of credit from banks
• Some commercial real estate loans
• Equipment financing with variable terms

SOFR (Secured Overnight Financing Rate)

SOFR replaced LIBOR (London Interbank Offered Rate) as the primary benchmark for institutional and commercial lending. LIBOR was phased out in 2023 following a rate-manipulation scandal. SOFR is now the dominant benchmark for larger commercial transactions and many adjustable-rate products.

What SOFR is: SOFR is a measure of the cost of borrowing cash overnight collateralized by U.S. Treasury securities. It's calculated and published daily by the Federal Reserve Bank of New York, based on actual transactions — not estimates, which was one of LIBOR's vulnerabilities.

How SOFR differs from Prime:

• SOFR is a backward-looking rate (based on yesterday's transactions). Prime is forward-looking (set in anticipation of Fed policy).
• SOFR can be more volatile day-to-day than Prime
• SOFR is primarily used in institutional and commercial real estate lending; Prime is more common in small business lending
• SOFR-based loans often use term SOFR (30-day, 90-day, 180-day averages) to smooth daily volatility

Products commonly tied to SOFR:

• Larger commercial real estate loans from institutional lenders
• Fannie Mae and Freddie Mac multifamily adjustable-rate mortgages
• CMBS floating-rate loans
• Some SBA loans (when structured as floating-rate above a certain amount)

The Spread: What's Above the Benchmark

Your actual interest rate = Benchmark + Spread. The spread is what the lender charges above the benchmark, reflecting:

• Your creditworthiness (lower credit score = higher spread)
• Loan type and collateral (unsecured = higher spread than secured)
• Loan term (longer term = often higher spread)
• Market conditions and lender competition

The spread is fixed at loan origination and doesn't change with market conditions. The benchmark moves; the spread doesn't.

How Rate Changes Affect Your Payment

Every 0.25% change in the benchmark rate changes your payment. How much depends on your loan balance and term.

Approximate payment impact per 0.25% rate change:

• $100,000 loan, 5-year term: ~$12/month per 0.25% change
• $500,000 loan, 10-year term: ~$57/month per 0.25% change
• $1,000,000 loan, 25-year term: ~$85/month per 0.25% change

For a business line of credit where you're drawing and repaying regularly, the rate change affects only the outstanding balance.

Rate Caps on Variable Loans

Some variable-rate loans include caps that limit how high the rate can go, regardless of benchmark movement. Common cap structures:

• Periodic cap: Limits how much the rate can change in any single adjustment period
• Lifetime cap: Maximum rate over the life of the loan

SBA 7(a) variable-rate loans have statutory rate caps — the rate cannot exceed a maximum established by SBA guidelines, regardless of how high Prime rises. This is a meaningful protection that not all variable-rate products provide.

Fixed vs. Variable: How to Choose

The fundamental tradeoff:

• Fixed rate: Certainty. Your payment doesn't change regardless of market rates. You pay a premium at origination for that certainty.
• Variable rate: Lower initial rate. If benchmarks fall, you benefit automatically. If benchmarks rise, your payment increases.

The right choice depends on your rate outlook, your cash flow sensitivity to payment changes, and your loan term. For short-term loans (under 3 years), variable is often preferable. For long-term loans in a rising-rate environment, fixed provides meaningful protection.

💡 BestLoanUSA can help you evaluate fixed vs. variable rate options for your specific financing need. Pre-screen with no credit impact.