A certificate of deposit locks your money away for a fixed term in exchange for a fixed rate — but the number the bank advertises (the APY) doesn't immediately tell you what you'll actually walk away with in dollars. A CD calculator turns that percentage into an actual maturity value in seconds.
The Formula
Since banks advertise CDs using APY — a rate that already accounts for compounding — projecting the maturity value is a matter of applying that rate across the exact term length:
Maturity Value = Principal × (1 + APY)^(Term in Years)
A Worked Example
Put $10,000 into a CD with a 5% APY for a 2-year term:
- Maturity value = $10,000 × (1.05)² = $11,025.00
- Interest earned = $1,025.00
That $1,025 is more than a simple 5% × 2 years × $10,000 would suggest ($1,000), because the second year's 5% is earned on $10,500, not the original $10,000 — the whole point of compounding.
Terms That Aren't a Whole Number of Years
CDs commonly come in terms like 6, 18, or 30 months — not always a clean number of years. The same formula still applies, just with a fractional exponent: an 18-month term uses 1.5 in place of the year count. On the same $10,000 at 5% APY, an 18-month term matures to $10,759.30.
Find your exact maturity value in seconds
Try the CD Calculator