Investment Calculator
Project a starting amount and regular contributions over a chosen number of years using your assumed effective annual return.
Calculator arithmetic runs locally in your browser and does not require an API.
The interactive calculator loads here when JavaScript is enabled.
How to use Investment Calculator
Select monthly or annual deposits. Contributions occur at the end of complete periods; any fractional remainder earns growth without another deposit.
Formula and method
Period return i = (1 + annual return)^(1/f) − 1. Contribution value = C[(1+i)^k − 1]/i; at 0%, it is C × k.
Understanding the results
Total invested includes the initial amount and deposits. Estimated growth is the difference from ending balance and can be negative. Constant returns exclude fees and taxes and are not guaranteed.
Worked example
With 1,000 initially, 100 deposited monthly for two years and 0% return, 24 deposits add 2,400. Ending balance and total invested are both 3,400.
These are mathematical estimates, not financial advice or an offer of credit.
Frequently asked questions
When are contributions added?
At the end of each complete monthly or annual contribution period.
Is this rate nominal or effective?
It is effective annual return. The period rate is derived so a full year matches that assumption.
Does the projection predict market performance?
No. It illustrates a constant return assumption; actual returns vary and losses are possible.