CD growth, in short
A CD locks in a fixed rate for a fixed term in exchange for not touching the money early. $10,000 at 5% for 12 months grows to about $10,512.67 with daily compounding — and that number barely moves if you switch to annual compounding instead. What actually drives the payout is the rate and how long you commit the money, not how often the bank compounds it.
Key takeaways
- $10,000 at 5% APY for 12 months with daily compounding grows to $10,512.67 — $512.67 in interest.
- Switching that same CD from annual to daily compounding only adds $12.67 (from $500.00 to $512.67 interest) — a minor factor compared to rate and term.
- Stretching the term from 12 to 60 months at the same 5% rate grows interest from $512.67 to $2,840.03 — term length matters far more than compounding frequency ever will.
- A typical 3-month early withdrawal penalty on that 12-month CD would claw back roughly $125 — about a quarter of the full year's interest.
How much compounding frequency actually matters
On $10,000 at 5% for one year, here's what each compounding frequency actually produces:
Annually: $500.00 interest
Quarterly: $509.45 interest
Monthly: $511.62 interest
Daily: $512.67 interest
The gap between the least and most frequent compounding on offer here is $12.67 — real money, but small next to the size of the deposit. Advertised compounding frequency is a minor factor in choosing a CD; the rate itself does almost all the work.
Why term length matters far more
Holding the rate and compounding fixed and varying only the term shows a much bigger swing:
12 months: $512.67 interest
24 months: $1,051.63 interest
60 months: $2,840.03 interest
Committing for five years instead of one earns more than five times the interest — not just five times because of compounding stacking on itself over the longer horizon. That's the lever worth focusing on, far more than shopping compounding frequency between otherwise similar CDs.
What an early withdrawal penalty actually costs
CDs charge a penalty for breaking the term early, commonly expressed as a number of months' interest. A typical 3-month penalty on the 12-month, $512.67-interest CD above works out to roughly $125 — nearly a quarter of the entire year's earnings, taken back for needing the money a few months sooner than planned. That math is exactly why CDs only make sense for money you're confident you won't need before maturity; a high-yield savings account is the safer home for anything less certain.
CD vs. high-yield savings
A CD trades flexibility for a locked-in rate: you know exactly what you'll earn by maturity, but early access costs you. A high-yield savings account keeps your money liquid, but its rate can move with the market at any time — up or down. CDs fit money earmarked for a known date (a house down payment in 18 months, a tax bill you know is coming); savings accounts fit money that needs to stay reachable, like an emergency fund.
Related calculators
For liquid, variable-rate savings instead of a locked term, see the savings calculator. The underlying compounding math also appears on its own in the compound interest calculator and interest calculator.