Investment Growth: invest a set amount every month
See what a fixed amount invested every month could become over the years, with an optional yearly increase. Every value is editable, and the results are illustrations, not forecasts.
An example value, replace it with yours.
Optional. 0 keeps the amount the same. The first increase applies from month 13.
Starts at an illustrative 6%, an assumption and not a forecast. Fill in one of the published starting points below or type your own. Real returns vary and can be negative.
Filled with the latest US consumer-price figure and used for the view in today's money. Leave it empty to hide that view.
Your results
Every payment and the final value are divided by (1 + inflation) for the years that pass, so they show today's buying power, at a real return of 2.22% a year. Unlike Spending Habits, the amounts you enter are not assumed to rise with inflation.
Final value
$22,596
10 years
- You pay in
- $20,093
- Of which growth
- $2,503
Paid in vs value
| Years | You pay in | Final value | Of which growth |
|---|---|---|---|
| 5 | $10,957 | $11,589 | $632 |
| 10 | $20,093 | $22,596 | $2,503 |
Putting in $2,400 each October
| Date | S&P 500 level | Put in | Source |
|---|---|---|---|
| Oct 29, 2021 | 4,605.38 | $2,400 | S&P Dow Jones Indices via FRED |
| Oct 31, 2022 | 3,871.98 | $2,400 | S&P Dow Jones Indices via FRED |
| Oct 31, 2023 | 4,193.8 | $2,400 | S&P Dow Jones Indices via FRED |
| Oct 31, 2024 | 5,705.45 | $2,400 | S&P Dow Jones Indices via FRED |
| Oct 31, 2025 | 6,840.2 | $2,400 | S&P Dow Jones Indices via FRED |
| Valued on Oct 22, 2026 at 7,663.43 | S&P Dow Jones Indices via FRED |
- Total put in
- $12,000
- Worth on that date
- $19,042
- Change
- +58.7%
Index level, price return only: no dividends, no fund fees. A fund tracking this index would also pay dividends and charge fees.
This is one path in the past. It does not predict the future, and it does not say which option is better.
Where the default numbers come from
- World stocks, long-run return (MSCI World, USD): 9.02% · MSCI World Index factsheet · as of Sep 30, 2026Annualised gross total return since 31 Dec 1987, including reinvested dividends. The 10-year figure was 13.37%, an unusually strong decade. Past returns don't predict future ones.
- 3-month US Treasury bill: 4.05% · 3-month US Treasury bill, secondary market (FRED DTB3) · as of Oct 27, 2026
- US savings account, national average: 0.38% · FDIC national average savings rate · as of Oct 19, 2026
- Inflation: 3.7% · US Bureau of Labor Statistics · as of Sep 30, 2026US consumer prices (CPI-U, all items), 12 months to September 2026.
The default 6% return is an illustrative assumption, not a forecast and not a published rate. Compare it with the published starting points above. Inflation starts at the US figure above.
How these figures are calculated
- The return is converted to an effective monthly rate, so 12 months of growth add up to exactly the yearly return you entered. Each payment is made at the end of its month.
- A yearly increase starts in month 13 and applies to every payment in that year, always worked out from the first amount.
- In today's money, a payment made in month m and the balance at month m are divided by (1 + inflation) raised to m/12. Unlike Spending Habits, the amounts you enter are not assumed to rise with inflation.
Simplifications: constant return, monthly payments at the end of each month, no taxes or fees. Education only, not financial advice.
Keep reading
Plain-language guides on the ideas behind this tool.
Education only, not financial advice. Results are estimates based on the numbers you enter.