Compound Interest Calculator Online
This compound interest calculator online helps you estimate how an initial investment and recurring monthly contributions may grow when interest is compounded over time. Enter your starting amount, monthly contribution, annual interest rate, investment length, and compounding frequency to see an estimated future value and total interest.
How Compound Interest Works
Compound interest means that interest is added to the balance and future interest can then be calculated on the accumulated balance. Over a longer period, compounding can make the growth of an account different from simple interest because previously credited interest can participate in future growth.
Compound Interest Formula
For a lump-sum investment with no recurring deposits, a common compound-growth formula is FV = PV(1 + r)n, where FV is future value, PV is present value, r is the rate per compounding period, and n is the number of compounding periods.
Compound Interest Calculator With Monthly Contributions
This calculator also supports a recurring monthly contribution. The contribution is added at the beginning of each simulated month, so the result can differ from calculators that assume deposits occur at the end of the month. This timing convention is important when comparing results with another compound interest calculator.
Compound Interest Calculator With Different Frequencies
You can choose annual, semi-annual, quarterly, monthly, or daily compounding. The calculator converts the selected nominal annual rate into an equivalent monthly growth rate for its monthly contribution model. This keeps recurring monthly deposits consistent while allowing the compounding frequency to affect the estimated growth.
| Frequency | Compounding periods per year | Typical label |
|---|---|---|
| Annually | 1 | Yearly compounding |
| Semi-Annually | 2 | Twice per year |
| Quarterly | 4 | Four times per year |
| Monthly | 12 | Twelve times per year |
| Daily | 365 | Daily compounding approximation |
Compound Interest Calculator for US and UK Users
People searching for a compound interest calculator USA, compound interest calculator UK, or a compound growth calculator can use the same core mathematics. This page displays values in US dollars ($). The actual rate, fees, tax treatment, deposit rules, and compounding method used by a bank or investment provider can differ by product and country.
Investment Growth and Future Value
The future value shown by the calculator is the estimated ending balance under the selected assumptions. Total principal includes the initial investment plus recurring contributions. Total interest earned is the difference between the estimated future value and total principal.
Example of Compound Interest Growth
With an initial investment of $1,000, no monthly contribution, a 7% annual rate, monthly compounding, and a 10-year period, the estimated future value is about $2,009.66. The estimated interest is about $1,009.66. Adding recurring contributions can materially change the result because additional money is invested over time.
What Can Affect Compound Growth?
- Starting amount: A larger initial investment changes the amount available to compound.
- Monthly contribution: Regular deposits add to the principal over time.
- Interest rate: A higher assumed rate generally produces a higher projected value, all else equal.
- Investment length: More time allows more compounding periods.
- Compounding frequency: The timing of interest crediting can affect the result.
- Contribution timing: Beginning-of-month and end-of-month deposits can produce different estimates.
Compound Interest vs Simple Interest
Simple interest is calculated from the original principal under the standard simple-interest method. Compound growth allows previously credited interest to affect later growth. Use the Simple Interest Calculator when the relevant calculation specifically uses simple interest.