Investment Calculator
Project an investment account with regular contributions, yearly raises to those contributions, and inflation.
| Ending balance | $292,465.03 |
|---|---|
| Total you put in | $130,000.00 |
| Investment growth | $162,465.03 |
| In today's dollars (2.5% inflation) | $178,482.91 |
How to use it
- Enter what is invested now and what you add each month.
- Enter an average yearly return. It is treated as the effective yearly growth, so 7% means the balance grows 7% over a full year.
- If you plan to raise your contribution every year (for example with each pay raise), enter that percent.
- Inflation turns the final balance into today's buying power.
Formula
Monthly rate i = (1 + annual return)^(1/12) − 1- Each month: balance = balance × (1 + i) + contribution (end of month), or (balance + contribution) × (1 + i) (start of month)
Today's dollars = ending balance ÷ (1 + inflation)^years
Example
$10,000 with no contributions at 7% a year for 10 years grows to 10,000 × 1.07^10 = $19,671.51. Investing $100 at the end of every month for 10 years at 7% instead grows $12,000 of contributions to $17,105.17. With the default inputs ($10,000 plus $500 a month for 20 years) you put in $130,000 and end with $292,465.03, or $178,482.91 in today's dollars at 2.5% inflation.
Questions
What return should I use?
There is no guaranteed number. Many people test a few: a cautious rate, a middle rate and an optimistic one. Bonds and savings accounts usually earn less than a stock-heavy portfolio over long periods, with less ups and downs.
How is this different from the compound interest calculator?
This one lets contributions grow each year, choose start- or end-of-month deposits, and adjust for inflation. The compound interest calculator is for a fixed rate with a chosen compounding frequency, like a savings account.
Are fees and taxes included?
No. To approximate fund fees, lower the return by the expense ratio (for example 7% − 0.5% = 6.5%).
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Last reviewed 2026-10-11. Found a mistake? Tell us.