How employer matches work
A match formula has two parts: how much the employer adds per dollar you put in, and the share of your pay it applies to. "50% of the first 6%" means that if you contribute 6% of your pay, your employer adds 3%. Contribute 4% and you get 2%. Contribute 10% and you still get 3%, because the match stops at 6%.
Tiered formulas stack. "100% of the first 3%, then 50% of the next 2%" pays 3% + 1% = 4% of salary if you contribute at least 5%.
Worked example
On a $75,000 salary with the 100%/50% tiered formula, contributing 4% puts in $3,000 and earns a $2,625 match. Raising your contribution to 5% adds $750 of your money and $375 more match, the full $3,000.
The front-loading trap
Many plans match each paycheck, not the year. If you contribute a high percentage you can hit the yearly limit by autumn. Your contributions stop, and so does the match. Some plans fix this with a year-end "true-up"; many do not.
A $200,000 earner contributing 15% with a 50%-of-6% match reaches the $24,500 limit after 22 of 26 paychecks. Without a true-up, the last 4 paychecks get no match, about $923 lost. Contributing 12.2% instead spreads the same money across the year and keeps the whole match.
2026 contribution limits
For 2026 the IRS limit on your own 401(k) contributions is $24,500. People aged 50 or over can add a $8,000 catch-up ($32,500 total), and people aged 60 to 63 can add $11,250 instead ($35,750 total). Employer match does not count toward these limits. Source: IRS, 401(k) limit increases to $24,500 for 2026.
What this leaves out
Vesting schedules, which can mean you lose some match if you leave early, are not modelled. Nor are profit-sharing contributions, the overall limit on combined contributions, or the IRS cap on the salary a plan can count. Check your plan documents for the exact formula.
Deciding between Roth and pre-tax contributions? Try the Roth vs traditional calculator. To see when your savings could support you, use the FIRE calculator.