Nominal Interest Rate

The word nominal is used in three ways, and it helps to know which one a quote means.

Nominal versus real is about inflation. A 5% nominal rate says your balance grows 5% in dollars. It says nothing about prices. If prices also rise 5%, the real rate of return is zero, and your money buys exactly what it bought before.

Nominal versus effective is about compounding. Regulation DD, which carries out the Truth in Savings Act, defines a deposit account’s interest rate as the annual rate paid that does not reflect compounding. The annual percentage yield (APY) folds in how often interest is credited over a 365-day year: APY = (1 + r ÷ n)^n − 1, where r is the nominal rate and n the number of compounding periods. A nominal 4% credited monthly becomes an APY of about 4.07%.

Nominal versus all-in cost is about fees. The Consumer Financial Protection Bureau explains that a mortgage interest rate is the yearly cost of borrowing and excludes fees, while the APR also reflects points, broker fees and other charges, so it is usually higher. All of these rates, APY and APR included, are nominal in the inflation sense. The table below sets them side by side.

A nominal rate bundles several kinds of compensation. The lender wants a real return for giving up the use of money, protection against expected Inflation, and extra pay for risks such as a long term, a borrower who might default, or an investment that is hard to sell. The approximate relationship, named for the economist Irving Fisher, is nominal rate ≈ real rate + expected inflation.

At the short end, the Federal Reserve anchors rates. Its Federal Open Market Committee sets a target range for the federal funds rate, the rate at which banks lend reserve balances to each other overnight. On September 16, 2026, the committee raised that range by a quarter point to 3.75%–4.00%, saying inflation remained elevated and that the move would support a timelier return to its 2% goal.

Rates on savings accounts, money market funds and variable-rate loans tend to follow the federal funds rate. Longer-term rates, such as those on a 30-year Mortgage or a 10-year Treasury note, depend more on what markets expect for inflation and growth over many years, so they can move differently from the Fed’s target.

The US Treasury publishes two daily yield curves that make the difference visible. The par yield curve shows nominal yields on regular Treasury securities, from 1-month bills to 30-year bonds. The par real yield curve shows real yields on Treasury Inflation-Protected Securities, or TIPS, whose principal rises with the CPI-U. On September 18, 2026, the 10-year nominal yield was 5.01% and the 10-year real yield 2.68%. Solving the Fisher equation for inflation, 1.0501 ÷ 1.0268 − 1, gives about 2.27% a year, a little below the simple 2.33-point gap usually quoted as breakeven inflation. The gap also holds risk and liquidity premiums, so treat it as an estimate.

That market estimate sat well below the 3.4% rise in the CPI-U over the 12 months to August 2026. Past inflation and expected inflation are different numbers, and a nominal rate is priced on the second. When a nominal rate falls short of actual inflation, the real rate is negative: a deposit paying 3% over that year gained dollars but lost buying power.

I bonds build the relationship into one rate: a fixed real rate kept for the bond’s life, 0.90% for bonds issued May 1 through October 31, 2026, plus an inflation rate reset every six months from the CPI-U, for a combined 4.26%.

Two accounts with the same nominal rate can pay different amounts if one compounds more often, and two loans with the same rate can cost different amounts if one charges more in fees. That is why federal disclosure rules put a second number beside the nominal rate.

Regulation DD requires banks to give both the APY and the interest rate in account disclosures. If an advertisement states a rate of return, it must state it as an APY, and the interest rate may appear only alongside it and no more prominently. When you shop for a CD or a high-yield savings account, compare APY with APY, as the worked example below shows. At today’s rates the compounding gap is a few hundredths of a point; the compound interest page shows how it widens with higher rates and longer horizons.

On the borrowing side, compare APR with APR, since a loan’s nominal rate leaves out its fees. An APR still does not reflect compounding, so interest left unpaid on a credit card grows faster than the card’s APR suggests.

Nominal rates are the numbers you see most often, on bank sites, loan offers and bond quotes. They are not wrong; they simply leave out inflation, compounding and fees, and any of the three can change which choice is better. Before comparing two rates or entering one into a financial plan, check which of those the number includes. A rate on a statement, a Treasury yield and a fund’s return all describe dollars, not buying power, until you adjust them yourself.