What This Calculator Does
The Microapp 401(k) Calculator projects your retirement balance from today to your target retirement date. It accounts for your current balance, contributions as a percent of salary, employer match (and its cap), and expected investment return. The output shows not just the final number, but where the money came from — your contributions, the employer's match, and most importantly, decades of compound investment growth.
• Current balance: $25,000
• Salary: $75,000
• Your contribution: 10% of salary ($7,500/year = $625/month)
• Employer match: 50% per dollar, capped at 6% of salary ($2,250/year)
• Expected return: 7%/year nominal
Total monthly going in: ~$813 (yours + employer's match)
Final balance after 30 years: ~$1,168,000
Of which:
• Your contributions: $225,000
• Employer match: $67,500
• Investment growth: $850,500 (73% of the final balance)
The market did most of the work. That's why starting young matters — every year of compounding is worth more than the last.
The Power of the Employer Match
If your employer offers a 401(k) match, capturing the full match is the single highest-priority financial move available to most W-2 employees. A typical match — 50¢ per $1 you contribute, up to 6% of salary — is an instant 50% return on your contributions up to that cap. No investment, no business venture, no side gig will reliably beat 50% guaranteed return.
Yet plenty of people leave match money on the table. The biggest failure modes:
- Not contributing at all: some workers don't enroll, especially in jobs with auto-enrollment defaults set to 0%. Check your benefits portal.
- Contributing below the match cap: if you contribute 3% but your employer matches up to 6%, you're capturing only half the available match.
- Front-loading early in the year and missing match: some employer match programs are calculated per pay period, not annually. If you hit the IRS limit ($23,500 in 2025) by mid-year, you may stop contributing — and your employer stops matching too. To get the full annual match, your contributions need to be spread evenly across all pay periods. Some plans have a "true-up" provision that backfills missed match at year-end; many don't.
If you're capturing less than your employer's full match, fix that first — before any other financial optimization.
Traditional vs Roth — Which 401(k) Type?
Most 401(k) plans offer both Traditional and Roth options. They differ in WHEN you pay tax:
| Aspect | Traditional 401(k) | Roth 401(k) |
|---|---|---|
| Contributions | Pre-tax (reduce taxable income now) | After-tax (no current tax savings) |
| Growth | Tax-deferred | Tax-free |
| Withdrawals in retirement | Taxed as ordinary income | Tax-free (after age 59½) |
| Best for | Tax rate now > tax rate in retirement | Tax rate now < tax rate in retirement |
Most people retire in a lower tax bracket than they earned in (because they don't have employment income), so Traditional often wins on the math. Roth wins when:
- You're early in your career, in a low tax bracket today, and expect higher income later
- You expect tax rates generally to rise over your lifetime (a defensible bet given long-term US fiscal trends)
- You want tax diversification — some money taxed now, some later — as a hedge against future tax law uncertainty
- You want flexibility on RMDs — Roth 401(k) can be rolled to Roth IRA which has no RMDs (Traditional has them starting at age 73)
A reasonable hedge: contribute 50/50 Traditional/Roth if your plan allows, until you have enough information to decide.
2025 Contribution Limits
| Account type | Under 50 | 50+ |
|---|---|---|
| 401(k) employee contribution | $23,500/year | $31,000/year (with $7,500 catch-up) |
| 401(k) total (employee + employer) | $70,000/year | $77,500/year |
| Roth IRA contribution | $7,000/year | $8,000/year |
| HSA contribution (single coverage) | $4,300/year | $5,300/year |
| HSA contribution (family coverage) | $8,550/year | $9,550/year |
Maxing out the 401(k) at $23,500/year for 30 years at 7% return: ~$2.4 million. Add a maxed Roth IRA at $7,000/year: another ~$700k. Add the employer match: another $400k+. Total: ~$3.5M+ for a steady, max-everything saver — without dramatic income or unusual market returns.
What Return Should You Assume?
The answer depends on your asset allocation and your time horizon:
- Stock-heavy (80%+ stocks): typical for younger workers. Historical S&P 500 nominal return ~10%/year, real return ~7%/year. Use 7-10% in projections.
- Balanced (60% stocks / 40% bonds): typical for mid-career. Historical ~7-8% nominal, 4-5% real.
- Conservative (40% stocks / 60% bonds): typical near retirement. Historical ~5-6% nominal, 2-3% real.
For projections more than 5 years out, use REAL returns (after inflation) and your final number will be in today's dollars — much easier to interpret. "$1M in 30 years" sounds great until you realize $1M in 30 years has the purchasing power of about $475k today (at 2.5% inflation). For nominal projections, use the calculator's default 7%.
Where 401(k) Plans Hide Costs
Not all 401(k)s are created equal. The hidden cost is fund expense ratios — the annual fee charged by the funds inside your plan. A high expense ratio (1%+) over 30 years can reduce your final balance by 20%+ versus a low-expense plan.
Good plans: offer index funds with expense ratios under 0.20%. Examples: Vanguard 500 Index (0.04%), Fidelity 500 Index (0.015%), iShares Core S&P 500 (0.03%).
Bad plans: only offer actively-managed funds with 0.75%+ expense ratios. Sometimes the only "good" option is a Target Date Fund with a 0.50%+ ratio.
If your plan has only high-cost options, contribute enough to capture the full employer match (which usually still beats the high fees) — but put any additional retirement money into a Roth IRA instead, where you have unlimited investment options at low cost.
What This Calculator Doesn't Capture
Salary growth. The calculator uses constant salary. Real salaries usually grow 2-4%/year for steady employment, more for promotions or job changes. Real outcomes are usually better than the projection.
Contribution rate increases. Many people increase their contribution rate periodically (e.g., +1% per year as a "save more tomorrow" plan). The calculator assumes constant rate.
Sequence of returns. Investment returns aren't smooth — they cluster in good years and bad. The calculator uses average return; real outcomes vary based on which years are good and bad. A bad market year right before retirement hurts much more than the same year early in your career.
Fees. Plan-level expense ratios reduce returns; the calculator uses gross returns. Subtract your plan's average expense ratio from the return assumption for a more accurate projection.
Job changes and rollovers. Most workers change jobs multiple times. Each change requires a decision: cash out (bad), leave with the old employer (often fine), roll into IRA (best for low fees), or roll into new 401(k) (depends on the new plan's quality).
Common Mistakes
Cashing out a 401(k) when changing jobs. Triggers a 10% early withdrawal penalty plus full income tax. On a $50,000 401(k), you might net $30,000 — losing 40%. Roll it over instead. Always.
Investing in too-conservative funds when young. A 25-year-old in a money-market fund will dramatically underperform their stock-allocation peers over 40 years. Time horizon should drive risk tolerance.
Investing 100% in your employer's stock. Concentration risk. If the company tanks, you lose your job AND your retirement savings simultaneously. Cap company stock at <10% of portfolio.
Not increasing contributions when income rises. Lifestyle inflation eats raises. The simple rule: every raise, increase 401(k) contribution rate by 1-2% before adjusting your spending.
Borrowing from your 401(k). 401(k) loans look free (you "pay yourself back with interest"), but you lose the market growth on the borrowed amount during the loan, and if you leave your job before repayment, the loan typically becomes a taxable distribution + penalty.
Educational Tool — Not Investment Advice
This calculator implements the standard future-value-of-annuity math for 401(k) projections. It assumes constant salary, contribution rate, and return — none of which is realistic in detail. For personalized retirement planning, consult a fee-only fiduciary financial advisor (not a commissioned product seller). For tax-sensitive decisions (Traditional vs Roth, RMD planning, withdrawal sequencing), a CPA or qualified tax planner is essential.
Related Tools
Use the Compound Interest Calculator to project growth on any investment account (not just 401(k)s). The Roth IRA Calculator handles individual retirement accounts, which most people should max alongside their 401(k). Track total assets in the Net Worth Calculator — your 401(k) is a major asset on the balance sheet.