Calculate certificate of deposit growth from opening deposit, APY and term length, with ending balance, interest earned, early-withdrawal note and a printable bank-offer comparison record.
Ending balance = opening deposit × (1 + APY decimal)^(term months ÷ 12). Interest earned = ending balance − opening deposit. Rough early withdrawal penalty = opening deposit × APY decimal × penalty months ÷ 12. Comparison balance uses the same formula with the comparison APY.
For a $10,000 CD at 4.5% APY for 12 months, ending balance = 10,000 × (1 + 0.045)^(12 ÷ 12) = $10,450.00. Interest earned is $450.00 before taxes, fees or any early-withdrawal penalty.
Master’s Tip: write the maturity date, renewal rule and early-withdrawal penalty on the printed record. A strong APY can be weakened by auto-renewal timing, liquidity needs or penalties that are not obvious in the headline rate.
Standard or basis: compound-growth calculation from published APY over a month-based term. This is an educational comparison calculator, not banking, investment, tax or deposit-insurance advice.
Methodology & Accuracy
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Ending balance = opening deposit × (1 + APY decimal)^(term months ÷ 12). Interest earned = ending balance − opening deposit. Rough early withdrawal penalty = opening deposit × APY decimal × penalty months ÷ 12. Comparison balance uses the same formula with the comparison APY.
Standard or basis: compound-growth calculation from published APY over a month-based term. This is an educational comparison calculator, not banking, investment, tax or deposit-insurance advice.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master’s Tip: write the maturity date, renewal rule and early-withdrawal penalty on the printed record. A strong APY can be weakened by auto-renewal timing, liquidity needs or penalties that are not obvious in the headline rate.
Convert APY to a decimal, raise 1 plus that APY to the term in years, multiply by the opening deposit, then subtract the opening deposit to find interest earned.
The maturity value is the estimated balance at the end of the certificate term before taxes, fees, withdrawal penalties or renewal changes.
It includes a rough months-of-interest penalty note for planning. Real penalties vary by bank and term, so the official disclosure controls.
Enter APY when the bank offer publishes APY. APY already includes compounding, so the maturity calculation can use it directly over the selected term.
Print the opening deposit, APY, term, maturity value, interest earned, comparison APY, penalty note, formula, assumptions, date, page URL and notes area for the bank or offer name.
Certificates of deposit turn time into part of the bargain: the saver accepts a fixed term, and the provider states a yield and withdrawal rules. A useful calculation separates the pure APY math from the account terms that must be checked.
The opening deposit is held for a stated term. The calculator converts that term into years and applies the published APY so the expected maturity value is visible.
A high APY is only useful if the saver can leave the money in place. Showing a rough penalty note beside the maturity value keeps liquidity risk from being hidden.
CD offers can change, renew automatically or include minimum-balance rules. A printed worksheet records the assumptions used on the day the offer was compared.