401(k) Calculator

The 2026 contribution limits

For 2026 the elective deferral limit — the most you may put in from your own pay across all 401(k), 403(b), and governmental 457(b) plans — is $24,500. From age 50 a catch-up of $8,000 is added on top, taking the total to $32,500.

There is a third tier. In the calendar year you turn 60, 61, 62, or 63, the catch-up rises to $11,250, giving a limit of $35,750. It drops back to the ordinary catch-up in the year you turn 64. This higher catch-up is something a plan may offer rather than something every plan does, which is why there is a checkbox for it rather than an assumption.

Two further limits sit above those. Employee and employer money together may not exceed $72,000 in one plan for the year (catch-up contributions sit outside that ceiling), and a plan may not take account of compensation above $360,000 — which quietly caps a percentage-of-pay match for high earners. All four figures come from IRS Notice 2025-67.

What the calculator does with a contribution above the limit

It tells you. A calculator that silently trims your input to the legal maximum leaves you thinking you asked for something you did not get, so this one shows the contribution you entered, the limit that applies to your age, the amount above it, and the figure actually used in the projection.

The limit is then applied in every year of the projection, not just the first. A rising salary eventually pushes a percentage contribution into the cap, and the projection reflects that rather than quietly exceeding the law for twenty years.

Roth catch-up contributions above $150,000

Under section 414(v)(7), a participant whose Social Security wages from the plan-sponsoring employer in the previous calendar year exceeded $150,000 must make catch-up contributions as designated Roth. For 2026, the test looks at 2025 wages.

This changes the tax treatment, not the amount: the catch-up still counts, it just goes in after tax and comes out tax-free. Enter last year's wages and the results panel will tell you whether it applies to you.

How the projection is built

The model runs one year at a time. Your contribution is taken from that year's salary and capped at the deferral limit for your age. The employer match is added under the formula you entered. The balance grows at the expected return, the annual fee is taken off the resulting balance, and salary grows into the next year.

Fees are charged on the balance rather than on the contribution, because that is how expense ratios and plan administration charges actually work — and it is why they matter far more later, when the balance is large, than in the early years.

The inflation-adjusted figure divides the ending balance by (1 + inflation)years, restating it in today's money. Over thirty years at 2.5% that roughly halves the headline number, and it is the more useful figure for deciding whether the plan is enough.

A worked example

Age 35, retiring at 65, $92,000 salary, $48,000 already saved, contributing 10% with a 50% match up to 6% of pay, 7% return, 0.4% fees, 3% salary growth.

The first year contributes $9,200 of your own money and $2,760 from the employer, well under the $24,500 limit. Thirty years later the projection lands near $1.7 million, of which roughly $428,000 is your contributions, $128,000 is employer money, and $1.2 million is growth. Fees take about $95,000 along the way.

Restated in today's money at 2.5% inflation that $1.7 million is closer to $816,000. Both numbers are true; the second is the one to plan with.

Notice the fee figure. Four tenths of one percent, charged annually on a growing balance, costs more than a fifth of what the employer contributed over the same period. Raising it to 1% — not unusual in a small plan — costs well over $200,000 of the ending balance.

What this does not model

• Market variability. A steady 7% every year is a modelling convenience. Real sequences of returns produce a wide range of outcomes around the same average, and a bad decade near retirement matters far more than a bad decade at the start.
• Future limit increases. The 2026 limits are held flat across the projection. They are usually adjusted for inflation, so a long projection understates what you will actually be allowed to contribute.
• Tax on withdrawal. Traditional 401(k) money is taxed as ordinary income when it comes out. The Roth vs traditional comparison handles that question directly.
• Vesting. Employer money is included in full. If you leave before you are fully vested, some of it is forfeited — the employer match calculator shows the vested figure.
• Loans, hardship withdrawals, and required minimum distributions. None is modelled.

For the whole picture including Social Security and the drawdown years, use the retirement calculator. See our sources for every figure used here and methodology for how they are verified.