By the numbers: The average 401(k) balance by age

A record number of 401(k) holders at Fidelity Investments hit millionaire status in 2018. Not one of them? You are in very good company. In fact, the average 401(k) balance at Fidelity — which is consistently ranked as the largest defined contribution record-keeper — was $106,500 as of September 2018. The median, which represents the middle balance between the highs and lows, is just $24,800.

Slightly more useful are the median and average balances by age. That's because the IRS sets contribution limits for 401(k) accounts, currently $19,000 per year ($25,000 for those 50 or older).

The below numbers show how 401(k) balances increase with age, at least until participants start drawing on their money in retirement.

Ages 20-29. Average 401(k) balance: $11,600. Median 401(k) balance: $4,000.

Many of the participants in this age group are new to working and new to saving for retirement. Yet even at this young age, it's important to prioritize contributing to your workplace retirement plan, especially if your employer matches a portion of your contributions.

Ages 30-39. Average 401(k) balance: $43,600. Median 401(k) balance: $16,500.

At this point, whether measured by the average or the median, participants have increased their balances roughly fourfold. One point that becomes increasingly important as participants age: Fidelity's analysis treats each account separately, which means balances aren't aggregated by account holder and then averaged. As people age and spend more time in the workforce, they're more likely to hold more than one 401(k).

Another solid jump by this age range, with both figures more than doubling, at least partly a product of peak earning years.

Ages 50-59. Average 401(k) balance: $179,100. Median 401(k) balance: $62,700.

This group has hit the age at which catch-up contributions are allowed by the IRS: Participants age 50 and older can contribute an extra $6,000 a year in 2019.

Ages 60-69. Average 401(k) balance: $198,600. Median 401(k) balance: $63,000.

Growth has slowed here, likely due to the fact that the latter half of this group may actually be drawing down their 401(k) balance. Following this, 401(k) balances begin to fall as more people start tapping their accounts. The average balance for those 70 and older is $186,800; the median is $52,400.