Updated for 2026. This calculator was originally created in 2007. Rest assured, it wasn’t crafted by AI! Many of you might be curious about how well your individual portfolio performed last year or during any specific timeframe. Imagine starting the year with $10,000 and making an additional $5,000 from 10 separate deposits throughout the year, ultimately reaching a total of $16,000. What’s your rate of return? The primary objective is to distinguish the impact of new deposits (or withdrawals) from the actual investment returns.
To determine your exact personal rate of return, you’ll need to know the precise dates of all deposits and withdrawals, along with access to a financial calculator or spreadsheet program with an IRR function (like the one provided here). However, if you’re looking for a quick and straightforward estimate, you can use this calculator:
How to Use the Calculator
- Determine your initial balance. This should be found on your brokerage statements, likely from January of the previous year.
- Sum up any deposits or withdrawals. For instance, if you contributed $3,000 to your Roth IRA and 5% of your $40,000 salary to a 401(k), your total would be $3,000 + $2,000 = $5,000. No need to pinpoint exact dates or amounts.
- Obtain your final balance. Your December statement should be readily accessible.
- Calculate the time elapsed (in years) between your initial and final balances.
- Click Calculate. The estimated annualized return will be provided immediately.
How Reliable Is This Estimate?
The calculator assumes that cash inflows and outflows are evenly distributed throughout the year. I initially encountered this approach in the book “The Four Pillars of Investing” (review). However, unless the deposits and withdrawals are significantly large relative to the initial balance, the estimates are quite accurate.
For instance, if you begin with $100,000 on January 1, 2025, and conclude with $120,000 on January 1, 2026, with net deposits of $10,000 during the year, the calculator will estimate your return at 9.52%. If the $10,000 was deposited all at once on a specific day, your exact returns would be as follows:
| Deposit Date | Exact Return |
| January 1, 2025 (very first day) | 9.1% |
| June 4, 2025 (middle of the year) | 9.5% |
| January 1, 2026 (very last day) | 10% |
| Estimate | 9.5% |
Don’t forget to explore the rest of my collection of Tools and Calculators.
