401(k) Calculator
Project your 401(k) balance at retirement from salary, employee deferral, employer match, expected return, and years to retirement — with the 2025 IRS limits applied automatically.
401(k) balance at retirement
£746,479.14
- Annual employee contribution
- £3,600.00
- Annual employer match
- £1,800.00
- Total annual addition
- £5,400.00
- Total contributed over horizon
- £189,000.00
- Employee contributed
- £126,000.00
- Employer contributed
- £63,000.00
- Investment growth
- £557,479.14
- Years until retirement
- 35
- Your elective deferral limit (2025)
- £23,500.00
Projects 35 years of $5400 annual additions ($3600 employee + $1800 employer) at 7% expected return using the ordinary-annuity formula FV = C · ((1+r)^n − 1) / r. Salary held constant; pre-tax balance shown — Traditional 401(k) withdrawals are taxed as ordinary income, Roth 401(k) qualified withdrawals are tax-free.
How to use this calculator
Enter your current age, the age you plan to retire, your annual salary, the percentage of salary you contribute to your 401(k), the percentage your employer adds (the effective match expressed as a % of salary), and an expected nominal annual return. The headline shows your projected 401(k) balance at retirement (pre-tax — Traditional withdrawals are taxed as ordinary income; Roth 401(k) qualified withdrawals are tax-free). The breakdown splits the total into employee versus employer contributions, total contributed over the horizon, and investment growth.
How the calculation works
The calculator first builds your annual contribution: salary × employee percentage, capped at the 2025 IRS elective deferral limit ($23,500 under 50, $31,000 with the 50+ catch-up under IRC §414(v)). Employer match is salary × employer percentage, with salary itself capped at the 2025 §401(a)(17) compensation limit of $350,000. The combined annual addition is capped at the §415(c) limit ($70,000, or $77,500 with catch-up). Future value uses the ordinary-annuity formula FV = C × ((1+r)^n − 1) / r, where C is the total annual addition, r is the expected annual return, and n is years to retirement. Salary is held constant — to model salary growth, run multiple scenarios and step the contribution up.
Worked example
A 30-year-old earning $60,000 contributes 6% of salary ($3,600/year) and the employer matches an effective 3% of salary ($1,800/year). Total annual addition: $5,400. Over 35 years to age 65 at 7% expected return, FV = 5,400 × ((1.07)^35 − 1) / 0.07 = 5,400 × 138.237 = $746,479. Total contributed: $189,000 ($126,000 employee + $63,000 employer). Investment growth provides the remaining $557,479. Boosting employee contribution from 6% to 10% — well under the $23,500 deferral cap — would raise the balance to about $1.05 million on the same assumptions.
Frequently asked questions
What are the 2025 401(k) contribution limits?
For 2025 the IRS limits employee elective deferrals to $23,500, with an additional $7,500 catch-up if you are 50 or older (so $31,000 total). SECURE 2.0 also adds a "super catch-up" of $11,250 for anyone aged 60–63 in 2025, bringing their limit to $34,750. The combined limit on employee plus employer contributions (the §415(c) annual addition) is $70,000, or $77,500 with the 50+ catch-up. Only the first $350,000 of compensation counts for plan purposes under §401(a)(17). Source: IRS Notice 2024-80, November 2024.
How does employer matching work?
A typical US 401(k) match is "50% of the first 6%" or "100% of the first 3% plus 50% of the next 2%" — effectively 3–5% of salary added by the employer when you contribute at least the matched amount. Enter the effective percentage of your salary that your employer would add at your chosen contribution level. If your employer match has a complex schedule, take the highest tier your contribution unlocks and convert to % of salary (e.g. a "100% of first 3%" match if you contribute at least 3% is just "3% of salary").
Should I contribute to Traditional or Roth 401(k)?
Traditional 401(k) contributions are pre-tax — you deduct now and pay ordinary income tax on withdrawal. Roth 401(k) contributions are after-tax — withdrawals (including growth) are tax-free if you are 59½ and have held the account 5 years. As a rule of thumb, choose Traditional if your current marginal tax rate is higher than your expected retirement rate, and Roth if the reverse holds or you want tax diversification. Younger savers in lower brackets often favour Roth; high earners closer to retirement often favour Traditional. The IRS limits are combined across both — the $23,500 cap applies to the sum, not each separately.
What return rate should I assume?
The S&P 500 has returned roughly 10% nominal and 7% real (after inflation) over the long run. A reasonable default is 7% nominal for a diversified stock-heavy portfolio (slightly conservative versus history). Use 5–6% for a balanced 60/40 portfolio, and 3–4% for a conservative bond-heavy mix. Past performance is not a guarantee — sequence-of-returns risk near retirement can change the picture even when the average is on target. Many planners run the projection at multiple rates to bound the result.
When can I withdraw from my 401(k)?
Penalty-free withdrawals start at age 59½. Withdrawals before that face a 10% early-distribution penalty on top of income tax, with limited exceptions (Rule of 55, hardship, SEPP under §72(t), birth/adoption, qualified disaster, terminal illness, domestic abuse, etc.). Required minimum distributions (RMDs) from Traditional 401(k)s start at age 73 (for anyone born 1951–1959) or 75 (born 1960 or later) under SECURE 2.0; Roth 401(k) lifetime RMDs were eliminated effective 2024. See our RMD Calculator for the IRS Uniform Lifetime Table factors.
How does the IRS compensation limit affect my match?
Under IRC §401(a)(17), only the first $350,000 of compensation in 2025 counts for plan purposes — including the base for employer matching contributions. If you earn $500,000 and your employer offers a 5% match, the match applies to $350,000, not $500,000, so the maximum employer addition is $17,500 — not $25,000. The calculator caps salary at $350,000 when computing the employer match. The $23,500 employee deferral limit is a flat dollar cap and does not scale with salary.