Here's how Fidelity crunches the numbers (from
August 2019):
Age 20–29:
Average 401(k) balance: $11,800
Median 401(k) balance: $4,300
Contribution rate (% of income): 7%
Age 30–39:
Average 401(k) balance: $42,400
Median 401(k) balance: $16,500
Contribution rate (% of income): 7.8%
Among millennials (which Fidelity defines as those born between 1981–1997), 38% of workers increased their savings in Q2 2019.2 This generation is the most likely to contribute to a Roth 401(k), too.
Age 40–49:
Average 401(k) balance: $102,700
Median 401(k) balance: $36,000
Contribution rate (% of income): 8.5%
Age 50–59:
Average 401(k) balance: $174,100
Median 401(k) balance: $60,900
Contribution rate (% of income): 10.1%
Age 60–69:
Average 401(k) balance: $195,500
Median 401(k) balance: $62,000
Contribution rate (% of income): 11.2%