Money calculators
Compound Interest Calculator
Estimate how a starting amount and recurring contributions could grow over time with compound interest. Return assumptions are estimates, not guarantees.
How this compound interest calculator works
The calculator starts with the amount entered, adds recurring contributions at the selected frequency and applies the return assumption at the selected compounding frequency. It then estimates the ending balance, total contributions and interest or growth earned.
Starting amount, contributions and compounding
The starting amount is included in total contributions. Recurring contributions are added at the start or end of each contribution period, depending on the advanced setting. Compounding frequency controls how often estimated interest or growth is applied to the balance.
Contribution frequency vs compounding frequency
Contribution frequency is how often money is added. Compounding frequency is how often the return assumption is applied. They can be different, so the calculator uses a consistent projection schedule to combine both timing choices.
Why return assumptions are not guarantees
The annual return or APY field is only an assumption for this estimate. Actual savings interest, investment returns, fees and inflation can change over time, so the result should be read as a scenario rather than a promise.
What this calculator does not include
This calculator does not provide financial, tax, legal, accounting or investment advice. It does not choose investments, guarantee returns or include tax, fees, inflation, market volatility, withdrawal rules or changing contribution amounts.
Key terms and assumptions
- Compound growth: Interest or growth is applied at the selected compounding frequency and can then earn additional growth in later periods.
- Total contributions: Total contributions include the starting amount plus all recurring contributions made during the projection.
- Annual return / APY: The annual return or APY is an assumption used for the estimate. It is not guaranteed.
- Contribution timing: Start-of-period contributions have slightly more time to compound than end-of-period contributions.
- Yearly projection: Yearly rows aggregate estimated contributions, interest or growth and ending balance for each projected year.
- Region settings: Region settings change defaults and currency formatting only. They do not convert exchange rates.
- General estimate: The calculator excludes tax, fees, inflation, market volatility, investment selection and changing returns.
FAQs
What is compound interest?
Compound interest means interest or growth can earn additional interest or growth over time.
Can I include monthly contributions?
Yes. Choose the contribution amount and contribution frequency that match the estimate you want to test.
What is compounding frequency?
It is how often interest or growth is applied to the balance in the projection.
Is annual return guaranteed?
No. The annual return or APY entered is only an assumption for this estimate.
Does this include tax or inflation?
No. It does not include tax, fees, inflation or market volatility.
Can the return be negative?
Yes. Negative returns are allowed down to a safe limit for scenario testing.
Why does contribution timing matter?
Contributions made earlier have more time to compound than contributions made later.
How is this different from the savings goal calculator?
The compound interest calculator projects growth over a fixed time. The savings goal calculator focuses on reaching a target amount or target date.