How it works
A CD ladder splits your money into CDs with different terms, so one matures every few months or every year. The calculator splits the amount evenly (the last CD takes any leftover cents) and grows each CD at its APY: amount × (1 + APY)^(days ÷ 365). When a CD matures it is rolled into the longest term at the rollover APY, so once the ladder is built every CD is a long-term CD and one still matures every period. In the example, $25,000 in five CDs of 1 to 5 years at 3.80% to 4.10% is worth $36,638.66 after 10 years, rolled over at 3.90%: $1,363.72 more than a savings account at 3.50%, and $24.68 less than putting everything in one 5-year CD, the price of having money come free every year.