Enter your deposit, the advertised APY, and the term — CDs quote APY directly, so this already accounts for compounding.
Most CDs charge a set number of months' interest if you cash out before the term ends.
US banks quote CD rates as APY (Annual Percentage Yield), which already bakes in compounding — so the math is simply maturity = deposit × (1 + APY)^(term in years). A $10,000 CD at 4.5% APY for 12 months matures to 10,000 × 1.045 = $10,450, exactly $450 in interest.
The stated interest rate (sometimes called APR in this context) is the rate before compounding is applied; APY is the actual annual return after compounding, so it's always equal to or slightly higher than the rate for the same account, depending on compounding frequency. US federal law (Truth in Savings Act) requires banks to advertise CD yields as APY specifically so consumers can compare accounts on equal footing — which is exactly why this calculator asks for APY rather than a nominal rate and a separate compounding frequency.
Nearly every CD charges an early withdrawal penalty, almost always expressed as a number of months' interest rather than a flat fee or percentage of principal — commonly 3 months for terms under a year, 6 months for 1–2 year terms, and up to 12 or even 24 months' interest for longer terms. In rare cases the penalty can eat into principal, not just interest earned, if you withdraw very early into a longer-term CD. Always confirm the exact penalty terms in your specific CD's disclosure before opening it, since these vary meaningfully bank to bank.
Yes — at any FDIC-member bank, CDs are insured up to $250,000 per depositor, per bank, per ownership category, identical to the protection on savings and checking accounts. If you're depositing more than that at one institution, spreading it across multiple FDIC-insured banks keeps the full amount protected.
A CD locks in today's rate for the full term and typically pays somewhat more than a savings account, but you lose access to the money without a penalty. A high-yield savings account keeps your money liquid but its rate can drop at any time the bank chooses. CDs make the most sense for money you're confident you won't need before the term ends and when you want to lock in a rate before it potentially falls; savings accounts make more sense for an emergency fund or money you might need on short notice.
The same concept — lock money away for a fixed term at a fixed, guaranteed rate — exists worldwide under different names. India calls it a Fixed Deposit (FD); see the FD Calculator for that market's quarterly-compounding convention and tax rules. The UK uses "fixed-rate bonds," and continental Europe uses "term deposits" (Festgeld in Germany, dépôt à terme in France). The underlying math — a fixed rate compounded over a fixed term — is identical; only the compounding convention, deposit insurance limits, and early-withdrawal rules differ by country.
Worked example: $10,000 for 24 months at 4.75% APY: maturity = 10,000 × (1.0475)^2 ≈ $10,972.56, or $972.56 in interest. If the bank's early withdrawal penalty is 6 months' interest, that's roughly 972.56 ÷ 2 ÷ 12 × 6 ≈ $243.14 — a meaningful chunk of the first year's return, which is exactly why matching the CD term to when you'll actually need the money matters more than chasing the single highest advertised rate.