The Internal Rate of Return Online Calculator at irrq.com is the most comprehensive and the best among the lot.
Calculation is is a four-step approach.
The first page asks the user to enter a header, which may be the name of the investment, the number of payments, and the stating month. This calculator allows up to 40 payments.
The second page allows for input of values, allowing the user to enter a date for each value, a description of payment, and the actual payment, for each value. The calculator has default values for purpose and the value, but the user can easily overwrite these values.
One advantage of this calculator is the facility to sort the data date-wise, meaning entry of data need not be in chronological order. In addition, unlike other online calculators, the user can input the exact date and give a supporting description for the value entered. A break in data or leaving one field blank and entering the date in the wrong format can, however, cause errors in calculations.
The initial sheet has 13 rows, and strangely, addition of a further five rows is possible only after the computation, and then requires re-computation.
The third page is computation of the result, and the fourth page allows saving the result for future use. Saving requires registering with the site and logging in.
Registering with the site and login in allows saving of the calculation. While the calculator is in English, registration is in German! Registration is simple and straightforward, requiring just the name, email, and password, but unless you know elementary German requires some guesswork!
While this online calculator is free, the website also offers a spreadsheet calculator compatible with MS Excel and OpenOffice for $12.
Images: Screenshots of identified sites taken by writer. Screenshot of irrq online calculator is of page 2