About the 401(k) Calculator
A 401(k) is one of the most powerful retirement tools available to most workers, especially when an employer match is involved - that match is essentially free money on top of your own contributions. Our 401(k) Calculator projects your balance at retirement, accounting for both your contribution and your employer's match.
How It Works
The calculator finds your monthly contribution from your salary and contribution percentage, then calculates your employer's match (capped at your contribution rate, since employers only match up to a certain percentage). Both amounts are combined and grown using compound interest over your years until retirement.
Formula & Methodology
Employer matches are almost always capped - commonly stated as something like '100% match up to 4% of salary' - meaning the match grows alongside your own contribution rate only up to that ceiling, then stops increasing even if you contribute more. This calculator applies that capping logic before combining your contribution and the match into one combined monthly amount, which then compounds using the same growth math as any other long-term projection.
Step-by-Step: Calculating It By Hand
- 1Multiply your salary by your contribution percentage to find your monthly contribution.
- 2Calculate your employer's match by applying the match percentage to your salary, capped at whatever ceiling your employer's match policy specifies.
- 3Add your contribution and the employer match together for the total monthly amount going into the account.
- 4Compound the current balance and combined monthly contributions forward over your years until retirement.
Examples
With a full match
An $80,000 salary contributing 8%, with a 4% employer match, and $15,000 already saved can grow to a substantial nest egg over 30 years - with a meaningful chunk coming from the employer match alone.
Contributing below the match
Contributing only 3% when the employer matches up to 4% leaves free matching money on the table - increasing your contribution to at least the match threshold is almost always worth it.
Advantages
- Separately shows your employer match, making its dollar value concrete
- Uses realistic compound growth over your full working timeline
- Helps you see the cost of contributing below your employer's match threshold
- Useful for testing how increasing your contribution percentage changes your outcome
Common Mistakes
- Contributing less than what's needed to get the full employer match - literally leaving free money unclaimed
- Not increasing contributions after a raise, letting the contribution percentage effectively shrink over time
- Assuming a flat rate of return every year, when real markets fluctuate significantly
- Forgetting 401(k) contributions have annual IRS limits that this simplified estimate doesn't enforce
Edge Cases to Watch For
- Contributing below your employer's match threshold means forfeiting free matching money permanently - that gap is never made up automatically.
- Annual IRS contribution limits apply to 401(k)s and aren't enforced by this simplified projection, which assumes your contribution percentage is always achievable.
- Employer matching contributions are often subject to a vesting schedule, meaning you may not keep the full matched amount if you leave the employer before vesting.
- Some employers use non-elective contributions or profit-sharing structures instead of a simple percentage match, which wouldn't be captured by this calculator's match model.
Common Use Cases
- Projecting retirement savings including employer match
- Deciding whether to increase your contribution percentage
- Understanding the true value of your employer's matching program
- Comparing 401(k) growth against other retirement accounts