Calculator guide
Estimate a certificate of deposit balance from a starting balance, a fixed nominal annual rate, and a number of years, with monthly compounding and no additional deposits. The entered rate is not APY.
Formula or method
Future value = P(1 + R/1200)^(12t), where P is starting balance, R is the nominal annual rate in percent, and t is years. No periodic contribution term is included.
How to use this calculator
- Set Starting Balance. The interface starts with 10000; replace it with the value for your scenario.
- Set Annual Return (%). The interface starts with 7; enter a nominal annual rate, not APY, and replace it with the value for your scenario.
- Set Years to Grow (years). The interface starts with 20; replace it with the value for your scenario.
- Compare the result with the worked example, then vary one assumption at a time so you can see what changes. This calculator has no additional-deposit input.
Worked example
Enter Starting Balance = $1,000; Annual Return = 12% nominal; Years to Grow = 1. Monthly rate = 12% ÷ 12 = 1%, so future value = $1,000 × (1.01)^12 = $1,126.83; total contributions (the starting balance only) = $1,000; interest earned = $126.83. No additional deposits are included.
Understanding the result
This illustration uses a fixed 12% nominal annual rate compounded monthly; that nominal rate is not APY. The example’s effective annual growth is about 12.68% under monthly compounding. Results are mathematical estimates, not a quote for a specific CD.
Limitations and assumptions
- Assumes the same nominal rate for the entire period and monthly compounding; it does not model CD-specific maturity, renewal, withdrawal penalties, fees, taxes, or changing rates.
- There is no additional-deposit or withdrawal input. The estimate is not APY, a bank quote, or a guarantee of actual returns.
- The worked example demonstrates the stated assumptions, not a recommendation about your personal circumstances.
Frequently asked questions
Which inputs should I check first?
For CD Growth, check Starting Balance, Annual Return (%) as a nominal rate rather than APY, and Years to Grow. There is no additional-deposit input; do not treat defaults as recommendations.
Why might my result differ from another tool?
Compare the other CD estimate’s rate convention, compounding interval, deposit rules, rounding, and assumptions. A matching title does not guarantee that both tools answer the same question.
Does a linked reference certify this result?
No. A reference can explain compound-interest mathematics, but it does not endorse this website, validate a specific CD rate, or establish personal suitability.
Sources
Educational and planning information only. Sources are attributed background or formula references, not endorsements. Verify consequential decisions with an appropriate qualified professional.