401k Calculator US – Free Calculator
401k Calculator US - Calculate 401k at Retirement
Last updated: Sep 14, 2026 | 1M Americans search 401k calculator monthly | Source: IRS, 401k rules
401k calculator shows how much your 401k will be at retirement. Example: $500/month for 30 years at 8% = $745K. You invest $180K, gain $565K. Tax-deferred growth.
401k Formula
Future Value = P × [((1+r)^n -1)/r] × (1+r) + Current × (1+r)^n where P=monthly contribution, r=monthly return, n=months, Current=current balance
Example: P=$500, r=8%/12=0.00667, n=360 months (30y), Current=$0: FV = $500 × [((1.00667)^360 -1)/0.00667] ×1.00667 = $745K
401k Rules US 2024
- Employee contribution limit: $23,000/year for 2024 ($1,916/month)
- Employer match: Often 50% up to 6% of salary - Free money, always take full match
- Tax-deferred: Contributions reduce taxable income, grows tax-free, taxed at withdrawal
- Withdrawal: 59.5 years without penalty, 10% penalty before + taxes
- Roth 401k: After-tax contributions, tax-free growth and withdrawal
FAQ
How much will $500/month 401k become in 30 years at 8%?
$500/month for 30y at 8% = $745K. Invested $180K, interest $565K.
Is 401k better than Roth IRA?
401k: Higher limit $23K/year, employer match, tax-deferred. Roth IRA: $7K/year limit, tax-free withdrawal, no RMD. Best: Max employer match in 401k, then max Roth IRA, then back to 401k.
What is good 401k return?
Historical S&P 500 ~10% CAGR, but use 8% conservative for planning. Past performance not guarantee.
Understanding a 401(k) projection
The projection combines the current balance, employee contribution and entered employer match, then compounds using an assumed return. It is not a forecast or guarantee. Vesting rules, plan fees, salary changes, taxes and contribution limits can change the outcome.
Verify current contribution and catch-up limits with the IRS retirement-plan contribution guidance and confirm the employer-match formula in your plan documents.
Frequently asked questions
Is this result financial advice?
No. It is an educational estimate based on the values entered and the stated formula.
Are real-world results guaranteed to match?
No. Fees, taxes, market movement, provider rules and execution can create differences.
Recommended Tools (Affiliate)
We recommend only genuinely useful tools. Affiliate disclosure: We may earn commission if you purchase via our links, at no extra cost to you. This helps us keep free tools free. Learn more
Estimate 401(k) balance with contributions and employer match
Model current balance, salary contribution, employer match, salary growth and years to retirement. Run conservative and optimistic return assumptions instead of treating one projection as certain. Employer plans use their own matching formula, vesting schedule and investment options.
For annual contribution eligibility and current limits, verify the latest IRS retirement contribution guidance. Compare after-tax retirement saving with the Roth IRA calculator.