How it works
A 401(k) grows from three sources: your payroll contributions, your employer's matching contributions, and investment returns on both.
A typical match is "50% of what you contribute, up to 6% of pay": if you put in 6%, your employer adds 3%. Contributing at least enough to get the full match is usually the highest-return move available, since it is an instant 50–100% return on those dollars.
The IRS limits how much employees can contribute each year and the limit changes periodically, so enter the current figure if you want contributions capped. Catch-up contributions for people 50 and older are not modeled.
Formula
Each year: you = salary × contribution %; match = min(you, salary × cap %) × match %; balance grows monthly at return ÷ 12
Questions people ask
Should I contribute enough to get the full match?
In almost every case, yes. The match is part of your compensation, and skipping it leaves money on the table.
Is the employer match vested immediately?
Not always. Many plans use a vesting schedule (for example, 20% per year over five years). Your own contributions are always 100% yours.
Does the match count toward my contribution limit?
No. The employee elective deferral limit covers only your own contributions. A separate, higher limit applies to total contributions from you and your employer combined.