If you have a 401(k) through work, there's a decent chance you set your contribution percentage once, when you first enrolled, and never touched it again. It's an easy thing to ignore. But moving that number up by just one percentage point, from say 6% to 7% of your salary, is one of the cheapest, least painful changes you can make to your long-term numbers. Here's why, with real math.
What 1% actually costs you per paycheck
Take a $50,000 salary. One percentage point of that is $500 a year, pre-tax. Split across 26 biweekly paychecks, that's $19.23 per paycheck before any tax effect.
But a traditional 401(k) contribution comes off the top before federal income tax is calculated, so you're not actually giving up the full $19.23. At a 12% federal bracket, the tax break brings the real cost down to about $16.92 per paycheck. That's the actual dent in your take-home pay for moving your contribution up by 1%, less than the cost of a fast food meal every two weeks.
Note that this tax break only applies to federal income tax. Social Security and Medicare still apply to your full gross pay regardless of how much goes into a traditional 401(k), so those two lines don't change.
What $16.92 every two weeks turns into
Here's the part that makes this worth doing. That extra 1%, left alone to grow at a 7% average annual return (a commonly used long-run historical assumption for a diversified stock-heavy portfolio, not a guarantee) over 30 years, grows to about $47,230. From giving up less than $17 every two weeks.
That number comes directly from the same calculation engine behind the 401(k) growth calculator, which models deposits applied at each year-end and the standard compound growth formula. You can plug in your own salary, current contribution, employer match, raise assumption and return rate to see your own version of this number instead of a generic one.
Why this specific 1% matters more than it looks
Most people think about 401(k) contributions as one big number: "I'm putting in 6% of my salary." But the math doesn't care about round numbers. Each additional percentage point compounds completely independently of the ones before it, for the exact number of years it has left to grow. A 1% bump made at age 25 has decades to compound. The same 1% bump made at age 55 has far less time, and the dollar result will be smaller, which is worth knowing if you're deciding when to make this change rather than whether to.
It's also worth remembering that this 1% shift doesn't change your employer match math unless your plan's match formula specifically depends on your own contribution percentage (many do, up to a cap). If your employer matches dollar-for-dollar up to 4% and you're already contributing 6%, bumping to 7% doesn't add any extra employer money, it's purely your own extra dollar working on your own behalf.
What this doesn't assume
This models a traditional, pre-tax 401(k). A Roth 401(k) is funded with after-tax money, so the tax-break math here (going from $19.23 down to $16.92 per paycheck) wouldn't apply the same way, a Roth contribution costs its full dollar amount out of your paycheck, with the benefit coming later at withdrawal instead. The 7% return assumption is a long-run historical average, not a promise, and real returns vary significantly year to year, including negative years. The 2026 401(k) employee contribution limit is $24,500, with an extra $8,000 catch-up allowed if you're 50 or older, per IRS guidance, so make sure your own contribution percentage stays realistic against your actual salary and that limit.
How this stacks with your existing contribution
It's worth being clear that the $47,230 figure is what the extra 1% alone grows into, completely separate from whatever your existing contribution percentage and employer match are already doing in the background. If you're currently contributing 6% with a 4% match, bumping to 7% doesn't replace or reduce either of those, it adds a third, independent growth stream on top. Over the same 30 years, your existing 6% and your employer's 4% match keep compounding exactly as they were, the new 1% is pure addition.
Why "just once" is enough to start
Unlike a lot of financial advice that requires an ongoing decision every month, a contribution percentage change in most 401(k) plans is a one-time setting. You log into your plan's portal, change 6% to 7%, and every future paycheck automatically reflects it without you having to think about it again. That's part of why this particular move is worth the five minutes: the effort is a single action, but the $47,230 result compounds for as long as you leave it running.
The takeaway
A 1% contribution increase on a $50,000 salary costs about $17 every two weeks after the tax break and can grow into roughly $47,230 over 30 years at a 7% return, entirely on its own, separate from whatever your existing contribution and match are already doing. If you haven't touched your contribution percentage since the day you signed up, that's worth five minutes in your HR portal. Try your own numbers on the 401(k) growth calculator to see what your specific 1% is worth.
Source: 2026 401(k) elective deferral limit ($24,500) and catch-up ($8,000, age 50+) per IRS Notice 2025-67 / IR-2025-111. 7% is a commonly used long-run historical return assumption for a diversified stock-heavy portfolio and is not guaranteed.
This is an educational estimate, not financial advice. See the disclaimer for more.
More money math in my book. Check out Money Math for Your 20s.