401k contribution rate: how I decided what percentage makes sense
Here's how the math works on starting a Roth IRA at different ages, with specific numbers that make the case for acting now.
Assumption: $6,500/year contribution (the 2023 limit), invested in a total market index fund at 7% average annual return.
Starting at 22: contributions for 43 years until 65. Final value: approximately $1,940,000. Total contributed: $279,500. Growth: $1,660,500.
Starting at 32: contributions for 33 years. Final value: approximately $930,000. Total contributed: $214,500. Growth: $715,500.
Starting at 42: contributions for 23 years. Final value: approximately $409,000. Total contributed: $149,500. Growth: $259,500.
The 10-year head start (age 22 vs 32) more than doubles the final value, even though you contribute only $65,000 more. That extra $65,000 in contributions produces $1,010,000 in additional final value — $15.50 in wealth for every $1 contributed in those first 10 years.
No investment offers that kind of leverage. Time in the market is the mechanism. Nothing replaces it.