401k Calculator: How to Project Your Retirement Savings in 2026

A 401k calculator runs the math on how your retirement account will grow between now and retirement. You enter your current balance, annual salary, your contribution percentage, your employer's match formula, expected rate of return and years until you retire.

Most 401k calculators use the future-value formula: FV = PV × (1 + r)^n + PMT × [((1 + r)^n - 1) / r], where PV is present value (current balance), r is the annual return rate divided by compounding periods, n is total periods, and PMT is the per-period contribution including match. Because contributions happen each pay period and earnings compound, small changes in contribution rate or return assumptions produce large differences over 20-30 years.

1. 1Gather your current numbers. Log into your 401k provider and note your current account balance, your annual gross salary, your current contribution percentage (including any Roth 401k deferrals) and your employer's match formula (for example, 100 % of the first 3 % plus 50 % of the next 2 %).

1. 1Calculate your total annual contribution. Multiply your salary by your contribution rate to get your annual deferral. Then calculate the employer match: if you earn $60,000 and contribute 5 %, you defer $3,000; a 100 % match on the first 3 % is $1,800, so total annual contribution is $4,800.

1. 1Choose a rate-of-return assumption. Historical stock-market returns average 10 % nominal per year; a diversified portfolio of stocks and bonds might return 7-8 %. Conservative calculators use 6-7 %; aggressive ones use 9-10 %. The difference between 6 % and 9 % over 30 years is enormous, so run multiple scenarios.

1. 1Enter years to retirement. Subtract your current age from your target retirement age (commonly 65 or 67). If you're 35 and plan to retire at 65, enter 30 years.

1. 1Adjust for future salary increases. Many calculators let you assume annual raises (typically 2-3 % cost-of-living plus merit). A salary-increase input compounds your contribution dollars each year, which significantly boosts the final number.

1. 1Review the projection and iterate. The calculator shows your balance at retirement. If the number is below your target, increase your contribution rate by 1-2 % and recalculate. Repeat until you hit your goal or the legal contribution limit ($23,000 employee deferral in 2024, $23,500 in 2026, indexed annually).

For more tools that automate financial math, visit our [free tools page](/free-tools).

In this scenario the current $15,000 grows to $15,000 × (1.07)^35 ≈ $160,000. The annual $5,500 contribution stream (increasing slightly each year if salary grows) compounds to roughly $613,000.

Employer match is free money: your company contributes a percentage of your salary when you contribute. Common formulas include dollar-for-dollar match up to 3-4 % of pay, or 50 cents per dollar up to 6 %.

When you input match into a 401k calculator, enter it as an annual dollar amount or let the calculator compute it from your salary and the match rate. For example, a $70,000 salary with a 4 % full match yields $2,800 employer contribution per year.

Ignoring inflation. A $1,000,000 balance in 30 years sounds huge, but inflation erodes purchasing power. At 3 % annual inflation, $1,000,000 in 2055 buys what $412,000 buys today.

Using overly optimistic return rates. Plugging in 12 % because you read about a great year in the S&P 500 sets you up for disappointment. Long-run stock returns are closer to 10 % nominal, and your 401k likely holds bonds or target-date funds that lower the blended return to 7-8 %.

Not accounting for fees. High-fee funds (expense ratios above 0.50 %) drag down returns. A 1 % annual fee turns a 7 % gross return into 6 % net.

Assuming no withdrawals or loans. The calculator projects uninterrupted growth. If you take a 401k loan or early withdrawal, you derail compounding.

The single biggest variable in any 401k calculator is the assumed annual return. A 30-year-old with $10,000 today and $500/month contributions reaches different endpoints depending on return:

That's a $1,073,000 spread between conservative and aggressive assumptions on the same contributions. No one knows future returns; the stock market has delivered roughly 10 % historically, but past performance does not guarantee future results.

You should recalculate at least once a year and whenever a major variable changes. Key triggers include:

• Annual raise or bonus. Update your salary input and consider increasing your contribution percentage by 1-2 %.
• Job change. New employer match formulas, vesting schedules or fund lineups alter projections.
• Market swings. After a big gain or loss, your actual balance differs from last year's projection.
• Life milestones. Marriage, kids or buying a home may change how much you can contribute or when you plan to retire.
• Legislative changes. Contribution limits, catch-up provisions (age 50+) and Roth 401k rules change periodically.

If you're also navigating career growth, our [career and income hub](/career-and-income) covers salary negotiation and side income that can boost 401k funding.

Use a 401k calculator when you want to model contribution changes, test employer-match scenarios or compare fund-return assumptions within that one plan. Use a full retirement calculator when planning withdrawal strategy, estimating required minimum distributions (RMDs after age 73) or coordinating Roth conversions.

Both tools rely on assumptions; neither replaces a detailed financial plan. For personalized advice, check our [find a pro directory](/find-a-pro) to connect with fee-only financial planners.

Automate annual increases. Many plans offer an auto-escalation feature: your deferral percentage rises by 1 % each year until it reaches a cap you set (commonly 15 %). This painless method ensures you don't forget to raise contributions after a raise.

Capture the full match first, then IRAs. If your employer matches 4 %, contribute at least 4 % to the 401k. Beyond that, if your 401k fund options carry high fees, consider maxing a Roth or traditional IRA ($7,000 limit in 2024-2026, $8,000 if 50+) before going back to increase 401k contributions.

Max out if possible. In 2026 you can defer $23,500 as an employee; those 50+ add a $7,500 catch-up for $31,000 total. Employer match sits on top of that limit.

For entrepreneurial readers building wealth outside a 401k, visit our [start a business section](/start-a-business) for self-employment retirement options like Solo 401k and SEP IRA.

What inputs do I need for a 401k calculator?

How accurate is a 401k calculator projection?

A 401k calculator is only as accurate as your assumptions. Market returns fluctuate year to year, so the actual balance will differ from any projection.

Should I use nominal or real returns in the calculator?

Nominal returns ignore inflation; real returns subtract inflation from the growth rate. If you want to know the future dollar amount, use nominal (7-10 % stocks).

Can I include Social Security in a 401k calculator?

How much should I contribute to my 401k each year?

At minimum, contribute enough to capture the full employer match (typically 3-6 % of salary). A common guideline is 10-15 % total savings rate (employee plus employer).