How much should I contribute to my 401(k)?

At minimum, contribute enough to get your full employer match — that's a 50-100% instant return on your money. Beyond that, aim to save 10-15% of your gross income for retirement. The 2024 401(k) contribution limit is $23,000/year ($30,500 if age 50+). If you maxed out a 401(k) at $23,000/year from age 30 to 65 at 7% return, you'd accumulate approximately $3.4 million.

The 4% rule (also called the Bengen rule) says you can withdraw 4% of your retirement portfolio in the first year, then adjust that amount for inflation each year, and your money should last at least 30 years. It's based on historical US stock and bond market data. On a $1 million portfolio, that means $40,000/year ($3,333/month) in the first year.

What rate of return should I use for retirement planning?

The S&P 500 has returned approximately 10% annually on average over the past 90 years — but after inflation, that real return is closer to 7%. For conservative planning, use 5-7% for a portfolio of mostly equities. Mixed portfolios (60% stocks, 40% bonds) have historically returned around 7-8% nominal. The closer you are to retirement, the more conservative (lower return) your assumption should be.

What is the UK State Pension and when do I get it?

The full new State Pension in 2024-25 is £221.20/week (£11,502.40/year). You receive it when you reach State Pension age — currently 67 for people born after April 6, 1960. You need 35 qualifying National Insurance years to get the full amount. You can check your State Pension forecast at gov.uk/check-state-pension.

At what age can I withdraw from a 401(k) without penalty?

In the US, you can make penalty-free withdrawals from a 401(k) starting at age 59½. Withdrawals before that age incur a 10% early withdrawal penalty plus ordinary income tax. At age 73 (2024), Required Minimum Distributions (RMDs) begin, requiring you to withdraw a minimum amount each year based on life expectancy tables.

💰 Finance ⭐ Popular

Retirement Calculator

Use this retirement calculator to see how much your savings will grow by the time you retire — and whether you're on track for the retirement income you need. Enter your current age, retirement age, existing savings, and monthly contributions to get a realistic projection adjusted for inflation.

Last reviewed: January 2026 Formula shown No signup required

Educational estimate. Calculator results are for planning and information only, not financial, tax, medical, legal, or engineering advice. Verify important decisions with official sources or a qualified professional.

Retirement Calculator

401(k), Pension & Savings Projection

Current Age

yrs

Target Retirement Age

yrs

Full Social Security age in the US is 66-67; State Pension age in the UK is 67.

Current Retirement Savings

Total current value across all retirement accounts (401k, IRA, pension pot, ISA, etc.).

Monthly Contribution

Include both your contribution and any employer match.

Expected Annual Return

The S&P 500 has averaged ~10% nominal (7% inflation-adjusted) over the long term. Use 5-7% for a conservative estimate.

Annual Inflation Rate

Used to show the inflation-adjusted (real) value of your savings. Long-run US average is ~2.5-3%.

📐 Formula & Method

Future Value of Current Savings (Compound Growth)

FV = PV × (1 + r)ⁿ

Where PV = current savings, r = monthly return rate (annual rate ÷ 12), n = months until retirement.

Future Value of Monthly Contributions (Annuity)

FV = PMT × [(1 + r)ⁿ − 1] ÷ r

This formula compounds your regular monthly contributions over the full period to retirement.

Inflation-Adjusted Value

Real Value = Total FV ÷ (1 + inflation rate)^years

Shows the purchasing power of your projected retirement savings in today's money.

4% Safe Withdrawal Rule

Annual Income = Total Savings × 4% | Monthly Income = Annual Income ÷ 12

The "4% rule" (Bengen, 1994) suggests withdrawing 4% of your retirement portfolio in year 1, then adjusting for inflation each year, to make savings last 30 years with high probability.

📋 How to Use

1
Enter your current age and the age at which you plan to retire.
2
Enter your total current retirement savings (401k, IRA, pension, etc.). Use 0 if you're just starting.
3
Enter how much you contribute monthly (include employer match if applicable).
4
Set your expected annual return — 7% is a common conservative long-term assumption.
5
Set the inflation rate — 2.5% is the US long-run average.
6
Click Calculate to see your projected savings, inflation-adjusted value, and estimated monthly retirement income.

💡 Key Insights

Starting 10 years earlier roughly doubles your retirement balance. The first $1 invested in your 20s typically grows to $20+ by age 65 at a 7% real return.
The "25× rule" is the inverse of the 4% rule — you need 25 times your annual expenses saved to fund a 30-year retirement.
Capturing your full employer 401(k) match is a 50–100% instant return — far higher than any investment you'll find elsewhere.
Inflation quietly halves your purchasing power roughly every 25 years at 3%. Always look at the real (inflation-adjusted) projection — not just the headline number.
Social Security typically replaces only ~40% of pre-retirement income (US). UK State Pension covers ~£11.5k/yr — well below the £14.4k "minimum" lifestyle benchmark.

🧮 Worked Examples

Age 35 → 65, $500/mo, 7%

Starting with $50,000 already saved and adding $500/month at 7% return until age 65.

Current age35

Retire65

Saved$50k

Monthly$500

Return7%

Result: Projected $993k · Real value ≈ $474k · Monthly income at 4% ≈ $3,310.

Age 25 → 65, $400/mo, 7%

Starting from $0 at age 25 contributing $400/month at 7%.

Current age25

Retire65

Monthly$400

Result: Projected $1.05M · Real value ≈ $321k. The extra 10 years adds ~$300k.

📊 How to Interpret Your Result

✅

Projected real value ≥ 25× expected annual expenses

On track for the 4% rule. You can support your current standard of living for 30+ years.

⚡

Projected real value 15–25× expenses

Workable with a partial Social Security/State Pension. Consider raising contributions by 1–2% of salary.

⚠️

Projected real value < 15× expenses

Significant shortfall. Increase contributions, delay retirement, or plan for reduced spending.

⚠️ Common Mistakes to Avoid

Using 10% return without inflation adjustment.

Fix: After ~3% inflation, the real return on equities has been closer to 6–7% historically. Plan in real terms.

Forgetting employer match in the contribution total.

Fix: Include your match (e.g. 50% of 6%) in the monthly contribution figure — it counts toward your future value.

Ignoring taxes on Traditional 401(k)/SIPP withdrawals.

Fix: Pre-tax accounts are taxed as income at retirement. Your real spendable balance may be 15–25% lower.

Assuming a constant rate of return.

Fix: Sequence-of-returns risk matters most in the 5 years either side of retirement. Stress-test with a 5% return scenario.

🎯 Who This Calculator Is For

🚀

Early-career professionals

See the dramatic effect of starting now vs. waiting 10 years.

🎯

Mid-career re-baseliners

Test scenarios: contribution bumps, retirement age, market-return assumptions.

🇬🇧

UK SIPP and workplace pension savers

Project pension pot growth in real terms against PLSA living standards.

How Much Do You Need to Retire?

A common rule of thumb is the "25× rule" — you need 25 times your annual expenses saved to retire comfortably. This is the inverse of the 4% safe withdrawal rate. If you spend $60,000/year, you need about $1.5 million saved. This target is based on historical stock market data showing that withdrawing 4% annually, adjusted for inflation, has almost always lasted 30+ years.

In the US, the average 401(k) balance at retirement age (65+) is approximately $232,000 according to Vanguard's 2023 data — but the median is only around $89,000, meaning many Americans are significantly underfunded. The Social Security Administration estimates that Social Security replaces about 40% of pre-retirement income on average.

In the UK, the State Pension in 2024-25 pays £11,502.40/year (about £959/month) for those with 35+ qualifying NI years. The minimum recommended retirement income is £14,400/year for a single person (PLSA Retirement Living Standards, 2024), with a "comfortable" retirement requiring £43,100/year. Auto-enrolment workplace pensions are designed to supplement the State Pension.

The power of compound interest means that starting early has an enormous impact. Someone who invests $500/month from age 25 to 65 at 7% will have about $1.3 million — while someone who waits until 35 to start the same contributions will only accumulate about $607,000. Starting 10 years earlier more than doubles the result.

🔬 Methodology & Accuracy

Formula: Future value uses monthly compounding for both the lump sum and annuity contribution streams. Real (inflation-adjusted) value divides nominal FV by (1 + inflation)^years. The 4% rule (Bengen, 1994) drives the monthly income estimate.

Data sources: IRS 2025 contribution limits ($23,500 for 401(k), $7,000 for IRA); UK State Pension figures from gov.uk; PLSA Retirement Living Standards 2024.

Last reviewed: January 2026 · Accuracy: Results are precise to two decimal places using IEEE-754 double-precision arithmetic. Intended for educational and planning use only.

For informational purposes only. Results are estimates based on the inputs and formulas provided. For financial, tax, medical, or legal decisions, consult a qualified professional. Rates and regulations change — always verify current figures with official sources.

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❓ Frequently Asked Questions

🧭 Next Steps

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