Investment return calculator

This page calculates an average rate of return for one or more investments, as an annual percentage rate. The average rate of return calculated here is also known as the internal rate of return. All calculations are done on your computer in your browser; no data is sent to the internet. Full instructions for using the calculator are available on my GitHub site.

For multiple investments in the same thing, like contributions to an IRA over many years, copy and paste data into the first box below in this format:

Column 1, date in MM/DD/YYYY or YYYY/MM/DD or DD Month YYYY format. Every line needs a date.
Column 2, dollar amount invested (positive) or sold (negative). All money in and out must be included, with a date!
Column 3, balance as of that date. Not every line needs a balance.

If you have the balance on some date that you did not invest, you can put it in with investment amount 0. Entries on each row should all be separated by tabs (as when copied from a spreadsheet) or by semicolons or by spaces if the date has no space. Don't mix separators within a single line. Dollar signs and commas will be stripped out from the input. Examples 1, 2, 3 show how this works.

Click the Calculate button, and results will appear in the second box. Suggestion: click in the box, select all (Ctrl-A), copy (Ctrl-C), and paste (Ctrl-V) into a spreadsheet. Results have five columns. The first three columns of the results are the same as the input. The fourth column ("Rate to") shows the average rate of return from the first date to the date on each row. The fifth column ("Rate since") shows the average rate of return from the date on the row to the last date. The rate of return will only be calculated for dates with a balance.

Disclaimer: This analysis is for illustration only and does not constitute investment advice.
Copyright 2026 Craig L. Zirbel