401k Contribution Calculator

About this calculator

A 401(k) is a US employer-sponsored retirement plan where a percentage of each paycheck is deducted pre-tax (or post-tax for a Roth 401(k)) and invested; per-paycheck contribution = gross pay x contribution rate, and many employers add a match — commonly something like 50% of contributions up to 6% of pay — on top. Spread across a year’s worth of pay periods, those per-paycheck amounts add up to the total annual contribution.

Employees size their contribution rate around two things: capturing the full employer match (leaving free match money on the table is the classic mistake to avoid) and staying under the IRS annual contribution limit, which is adjusted most years for inflation. Because the deduction is typically pre-tax, it also lowers current taxable income, which is why payroll and HR teams frequently field questions about exactly what a given contribution percentage will cost someone per paycheck versus what actually lands in the account with the match included.

This calculator takes your salary, contribution rate, employer match terms and number of pay periods and shows what comes out of each paycheck, what your employer adds, and your total for the year.