An employer match is a promise to add money to your retirement account for every dollar you put in yourself, usually up to a set percentage of pay. This calculator splits that promise into the slice you are actually capturing and the slice you are leaving on the table, then compounds both forward so you can see what either amount grows into by the time you stop working.
What counts as capturing the full match
A typical US 401(k) match formula reads something like 'we add 50 cents per dollar up to 6% of pay' or a straight dollar-for-dollar match up to some cap. Capturing the full match means your own contribution rate meets or beats that cap; anything below it and part of the match simply never gets paid into your account.
The gap most workers miss is subtle: setting your contribution at the same number the plan uses for its formula, without checking whether that number is the cap or the multiplier. A plan that matches 100% up to 6% pays nothing extra if you contribute 3%, even though 3% sounds like a reasonable savings rate on its own.
As a benchmark, a worker who consistently captures a 4-6% match on top of their own 4-6% contribution is putting away roughly 8-12% of salary a year before any further personal saving, which sits close to the range most retirement planners treat as a workable starting point.
Two contribution rates, one salary
Take a 64,000 salary with a plan that matches dollar-for-dollar up to 5% of pay. Contributing 3% instead of 5% brings in 1,920 a year in match money, but leaves 1,280 a year unclaimed because the last two percentage points of the cap go unmatched. Over 30 years at a 7% return, compounded monthly, that captured match alone grows to roughly 195,000. The uncaptured 1,280 a year, had it been claimed, would have grown to roughly 130,000 — money the plan was willing to pay that never left the employer's pocket for the employee's benefit.
Now take a 95,000 salary with a lower cap: the plan matches up to 4% of pay, and the worker already contributes 6%. Here the match is fully captured at 3,800 a year, because contributing beyond the cap does not pull in any extra match, only extra personal saving. Over 20 years at 6.5% that captured match compounds to roughly 155,000, and there is no missed-match figure to chase.
A third case shows how much a low starting rate costs: a 52,000 salary, a 6% cap, and a worker contributing only 2%. The captured match is just 1,040 a year against 2,080 a year missed. Run 35 years at 7% and the missed amount alone would have grown to roughly 312,000 — more than double the 156,000 the worker actually secured, simply because the contribution rate sat four points below the cap for decades.
Why the missed-match number understates the real cost
The missed-match figure only counts the employer's money that never arrived. It does not include the employee's own contribution that would have accompanied it, so the total retirement shortfall from under-contributing is always larger than the number shown here, often by a factor of two once you add back the personal share.
It also assumes the return used applies uniformly to both the captured and missed portions, and that the worker stays employed at the same plan for every year in the horizon. A job change usually resets vesting on the employer's contributions even if it does not reset your own, and some plans vest employer money on a schedule of three to six years rather than immediately.
Pay rises are not modelled here even though most plans apply the match percentage to current salary; a rising salary raises both the matched and missed dollar amounts each year, so a static-salary projection is conservative relative to a real career with raises.
Where the formula breaks down
The calculator assumes a simple percentage match up to a single cap. Real plans often use tiered formulas, such as 100% on the first 3% and 50% on the next 2%, which changes the effective marginal match rate partway through the range and needs the tiers averaged before you can use a single cap figure here.
It also assumes contributions are unaffected by IRS annual limits. In 2025 the elective deferral limit for 401(k) plans is 23,500, and workers earning enough that a chosen percentage would exceed that limit will see their actual contribution capped well before the percentage suggests, which lowers both the personal and matched amounts.
Finally, the projection compounds at one constant return with no volatility and no fees. Real account growth is uneven year to year, and plan administration fees typically shave a small amount off the return actually credited, so treat the retirement-age figures as an ordering of options rather than a forecast to the dollar.
Jurisdiction and timing notes
In the United States, matches are made inside 401(k), 403(b) or similar employer plans and are subject to IRS contribution limits and plan-specific vesting schedules; check your plan's summary plan description for the exact formula and vesting timeline rather than assuming a flat dollar-for-dollar rate.
In the UK, the closest equivalent is a workplace pension under auto-enrolment, where the statutory minimum is a combined 8% of qualifying earnings with at least 3% coming from the employer; many employers match above that minimum, and the qualifying earnings band, not full salary, is what the percentage applies to.
Contribution limits and match formulas are reviewed periodically by regulators and can change at the start of a tax year, so re-check the current cap and any recent plan changes before relying on a percentage you set some years ago.
Frequently asked questions
- What does it mean to leave free money on the table?
- It means contributing below the percentage your employer matches, so part of the match formula never gets triggered. On a 64,000 salary with a 5% match cap, dropping your own contribution from 5% to 3% forfeits 1,280 a year in employer money that was otherwise available for no extra cost to you.
- Is it worth contributing more than the match cap?
- The match itself stops growing once you pass the cap, but the tax treatment and long-term compounding of your own money still make additional contributions worthwhile if you have room under the IRS or scheme limit and no higher-priority debt to pay down first.
- How much is an employer match really worth over a career?
- It depends heavily on salary, the cap, and the horizon. In one example here, capturing a 3,800 annual match on a 95,000 salary over 20 years at 6.5% compounds to roughly 155,000, entirely from employer contributions the worker never had to save personally.
- Does the match count toward the IRS contribution limit?
- No. The 2025 elective deferral limit of 23,500 applies to what the employee defers from pay; employer matching contributions are added on top under a separate, higher combined limit, so a fully captured match does not use up your personal deferral room.
- What happens to the match if I leave my job early?
- Your own contributions are always fully yours, but employer matching contributions are frequently subject to a vesting schedule, commonly phasing in over three to six years. Leaving before you are fully vested can forfeit part or all of the employer's contributions even though the calculator here assumes full vesting.
- Why does raising my contribution rate by a small amount matter so much?
- Because it is usually the last few percentage points before the cap that determine whether the match is fully captured. Moving from 2% to 6% on a 52,000 salary with a 6% cap turns 1,040 of captured match into the full 3,120 available, and that gap compounds for decades rather than sitting flat.
Sources
- IRS — 401(k) contribution limit increases for 2025 — Elective deferral limit for 401(k), 403(b) and most 457 plans set at 23,500 for 2025.
- GOV.UK — workplace pensions and auto-enrolment contribution rates — Minimum combined contribution of 8% of qualifying earnings, with at least 3% from the employer, in effect since April 2019.