CD Interest Calculator
CD maturity, interest, and APY.
What it does
Certificates of deposit pay a fixed nominal rate on a fixed term with compounding doing the quiet work. Monthly compounding beats annual at the same nominal quote because each credit starts earning sooner. APY compresses frequency and rate into one comparable number.
The tool above compounds the deposit. With $10,000 at 4% for 5 years monthly, maturity is $12,209.97 with $2,209.97 interest at 4.074 % APY. A $5,000 case at 5% for 3 years daily gives $5,809.11 with 5.127 % APY. Frequency gaps stay small but real across years.
Shopping needs APY, not nominal alone. Two 4% quotes differ when one compounds daily and the other annually, and callable or bump features change the deal further. Early withdrawal penalties can erase months of interest, so read those terms beside the yield.
This page models one fixed rate to maturity. It does not handle rate changes, add on deposits, penalties, or taxes. For ladders, run one rung at a time.
How to use
- Enter the opening deposit.
- Enter the nominal annual rate.
- Enter whole or fractional years.
- Pick the compounding frequency.
- Read maturity first, then interest.
- Compare APY across offers.
Formula
- P
- Opening deposit in dollars.
- r
- Nominal annual rate as a decimal.
- n
- Periods per year: 1, 2, 4, 12, 365.
Fixed nominal rate with annual, semi, quarterly, monthly, or daily compounding. At zero rate the maturity is principal. Early withdrawal penalties and taxes sit outside this math.
Worked example
Example: $10,000 at 4% for 5 years
Defaults: $10,000 at 4% nominal for 5 years with monthly compounding. Penalties excluded.
- Inputs: $10,000 at 4% for 5 years, monthly.
- Factor: (1 plus 0.04/12) to the 60th.
- Maturity: 10000 times factor is $12,209.97.
- Interest: $12,209.97 minus $10,000 is $2,209.97.
- APY: (1 plus 0.04/12)^12 minus 1 is 4.074 % APY. Tool shows the same.
Reference table
| Terms | Maturity | APY |
|---|---|---|
| 10000 4% 5yr monthly | $12,209.97 | 4.074 % APY |
| 5000 5% 3yr daily | $5,809.11 | 5.127 % APY |
| 2000 3% 1yr annual | $2,060.00 | 3 % APY |
| 1000 6% 10yr annual | $1,790.85 | 6 % APY |
| 7500 2.5% 2yr quarterly | $7,883.31 | 2.524 % APY |
Limits
- One fixed rate. Variable rates excluded.
- No add ons or withdrawals.
- Penalties ignored.
- Before tax.
Common mistakes
- Shopping nominal instead of APY.
- Ignoring compounding frequency gaps.
- Forgetting early withdrawal penalties.
- Comparing terms of different lengths as if equal.
- Reinvesting blindly at maturity rates.
Try it yourself
Quick checks. Answers sit tucked under each question.
$5,000 at 5% for 3 years, daily?
Maturity is $5,809.11 with $809.11 interest at 5.127 % APY.
$2,000 at 3% for 1 year, annual?
Maturity is $2,060.00 with $60.00 interest at 3 % APY.
Questions
How is CD maturity figured?
A = P(1+r/n)^(n t). Here $12,209.97 with $2,209.97 interest.
How is APY figured?
APY = (1+r/n)^n minus 1. Here 4.074 % APY.
Does frequency matter?
More frequent compounding pays slightly more at the same nominal rate.
What happens at 0%?
At 0% the balance never moves. A $2,000 annual case stays $2,060.00 only with rate, not at zero.