US CD Interest Calculator Maturity Value, Interest & APY
See exactly what your certificate of deposit is worth when the term ends — from the advertised APY or the nominal rate, with the growth charted month by month.
Reg DD arithmetic
The math follows the Truth in Savings Act formula banks themselves must use: APY = (1 + rate/n)^n − 1.
US banking product
Certificates of deposit are a US product with FDIC insurance and US-style APY quotes — this tool works in US dollars.
What is a certificate of deposit?
A fixed sum, locked for a fixed term, at a fixed rate
A certificate of deposit (CD) is a savings product offered by US banks and credit unions: you deposit a fixed amount for a fixed term — typically 3 months to 5 years — and the institution pays a fixed rate, usually higher than a regular savings account. According to the Consumer Financial Protection Bureau, the trade-off is liquidity: withdrawing before maturity almost always triggers an early-withdrawal penalty. Deposits are FDIC-insured up to $250,000 per depositor, per bank, per ownership category.
US banks are required by Regulation DD (the Truth in Savings Act) to advertise deposit accounts by their annual percentage yield. The APY already folds the compounding into a single annual number, which is why this calculator's APY mode needs no compounding frequency: a 4.50 % APY grows your balance by exactly 4.50 % per year, pro-rated for partial years. If your paperwork instead lists a nominal interest rate plus a compounding frequency, the nominal mode applies the classic compound-interest arithmetic and derives the APY for you — using the same formula Regulation DD prescribes in its Appendix A.
Maturity = Deposit × (1 + rate/n)^(n × years), APY = (1 + rate/n)^n − 1The difference between the two quotes is small but real: the more often interest compounds, the more the APY exceeds the nominal rate. That is exactly why the APY is the number to compare when shopping — two CDs with the same nominal rate but different compounding do not pay the same.
Find the growth factor
In APY mode a 4.5 % APY over 12 months means the balance grows by a factor of (1 + 0.045)^1 = 1.045. For an 18-month CD the exponent becomes 1.5 years.
Apply it to the deposit
10,450.00 at maturity — the interest stays in the CD and keeps compounding until the term ends.
Read the interest earned
Maturity value minus deposit: 10,000 = $450.00 of interest, reported to the IRS on Form 1099-INT in the year it is credited.
Longer terms usually pay higher rates, but the money is locked: the CFPB notes that early-withdrawal penalties commonly cost several months of interest — on short CDs they can even eat into the principal you deposited. Check the penalty schedule in your account agreement before choosing a term, and never put an emergency fund into a single long CD.
A common middle path is a CD ladder: splitting the deposit across staggered terms (for example 12, 24, and 36 months) so a portion matures every year. Each rung can then be re-invested at the current long-term rate, keeping average yield high while restoring liquidity at regular intervals.
For context on whether a quoted rate is competitive, the FDIC publishes national average deposit rates every month — online banks routinely pay several times the national branch average for the same term. A CD is worth comparing against high-yield savings accounts (flexible but variable-rate) and Treasury bills (state-tax-exempt) at the same maturity.
The headline number is the maturity value — what the bank pays out when the term ends if you leave the interest in the CD. The interest-earned figure is your actual dollar gain, and the APY restates it as an annual rate so you can compare offers with different terms and compounding. The growth curve shows how compounding accelerates: the later months of a long CD add more dollars than the early ones, because interest is earning interest.
Two things the maturity value does not tell you: purchasing power and taxes. Inflation reduces what the payout buys, and CD interest is taxed as ordinary income in the year it is credited — not at maturity — so a multi-year CD generates a 1099-INT every year even though you cannot touch the money.
The calculator models a standard fixed-rate CD held to maturity with interest left to compound. It does not model early-withdrawal penalties (bank-specific — check your disclosure), bump-up or step-rate CDs whose rate changes mid-term, callable CDs, or monthly interest payouts to a linked account (which stop the compounding and reduce the total earned below the figure shown here).
Informational purposes only
Results are estimates for informational purposes and not financial advice. Verify the APY, compounding, term, and penalty schedule against your bank's Truth in Savings disclosure before opening an account, and consult a financial professional for decisions involving significant sums. FDIC insurance limits ($250,000 per depositor, per insured bank, per ownership category) apply to the combined balance of all your accounts at one institution — not per CD.