🎯 Retirement Planner Calculator

Retirement planning has two distinct phases: the accumulation phase (working years, saving money) and the withdrawal phase (retirement, spending it). This calculator focuses on the accumulation phase — projecting how large your nest egg will be at retirement — then uses the 4% rule to estimate whether that amount is enough to fund your retirement expenses.

Enter your current age, your target retirement age, how much you've already saved, how much you contribute each month, your expected investment return, and your planned monthly spending in retirement. The calculator shows your projected corpus, the required corpus, and whether you're on track — in real time as you adjust each input.

The projected corpus combines two components: the future value of your existing savings (a lump sum growing at compound interest) and the future value of your ongoing monthly contributions (an annuity).

FV of existing savings: S × (1 + r)ⁿ

FV of monthly contributions: M × ((1 + r)ⁿ − 1) / r × (1 + r)

Total projected corpus = FV of savings + FV of contributions

• S — current savings balance
• M — monthly contribution amount
• r — monthly interest rate (annual rate ÷ 12)
• n — total months until retirement (years × 12)

Worked example (calculator defaults): You are 30, plan to retire at 65 (35 years, 420 months), have $25,000 saved, contribute $1,000 per month, and expect an 8% annual return.

• Monthly rate r = 0.08 ÷ 12 = 0.00667
• FV of $25,000 savings = $25,000 × (1.00667)⁴²⁰ ≈ $407,000
• FV of $1,000/month contributions ≈ $2,307,000
• Projected corpus ≈ $2,714,000

At $5,000 per month in retirement expenses ($60,000/year), the required corpus is $60,000 × 25 = $1,500,000. The projected $2.7M exceeds the target by over $1.2M — comfortably on track.

The 4% rule is the most widely used benchmark for determining how large a retirement portfolio needs to be. It comes from research by Cooley, Hubbard, and Walz — commonly called the Trinity Study — which found that a portfolio of 50–75% equities could sustain withdrawals of 4% of the initial balance per year for at least 30 years with a high probability of success across historical market scenarios.

The practical shorthand: multiply your planned annual retirement spending by 25 to get your target portfolio size. A household spending $60,000 per year needs $1,500,000. One spending $80,000 per year needs $2,000,000.

Important caveats the rule does not account for:

• Inflation: The rule was modelled with inflation-adjusted withdrawals. In reality, spending needs tend to rise over a 30-year retirement.
• Sequence of returns risk: A market downturn early in retirement can significantly shorten portfolio longevity even if long-run returns are acceptable.
• Longer retirements: The rule was validated for 30-year retirements. Retiring at 55 with a 40-year horizon may require a more conservative withdrawal rate of 3–3.5%.
• Social Security: Any guaranteed income (Social Security, pension) reduces the portfolio withdrawal needed and effectively increases your safe withdrawal rate on the remaining balance.

This calculator uses the 4% rule (25× annual expenses) as the required corpus target because it is the most widely recognized and empirically tested baseline. Adjust your monthly expense figure to exclude any guaranteed income sources you expect to receive.

The most reliable way to accelerate retirement savings is to maximise contributions to tax-advantaged accounts before investing in taxable accounts. The IRS sets annual limits on how much you can contribute to each account type.

• 401(k) / 403(b): $23,500 per year (2025). If you are 50 or older, an additional catch-up contribution of $7,500 is allowed, bringing the total to $31,000. Employer matching contributions do not count toward this limit.
• IRA (Traditional or Roth): $7,000 per year (2025), or $8,000 if you are 50 or older. Roth IRA contributions are subject to income phase-outs; Traditional IRA deductibility depends on whether you have a workplace plan.
• HSA (if you have a high-deductible health plan): $4,300 individual / $8,550 family (2025). Triple tax advantaged — contributions are pre-tax, growth is tax-free, and withdrawals for qualified medical expenses are tax-free. After age 65, withdrawals for any purpose are treated like Traditional IRA distributions.

If your employer offers a 401(k) match, contribute at least enough to capture the full match before allocating elsewhere — it is an immediate 50–100% return on that portion of your savings. See current limits at the IRS Retirement Plan Contribution Limits page.

How much money do I need to retire?

The standard answer: multiply your expected annual retirement spending by 25. If you plan to spend $50,000 per year in retirement, you need $1,250,000. If you plan to spend $80,000 per year, you need $2,000,000. This is derived from the 4% safe withdrawal rule — the principle that a diversified portfolio can sustain a 4% annual withdrawal rate for at least 30 years. Any guaranteed income you'll receive (Social Security, a pension) reduces the portfolio balance you need to fund. Subtract your expected annual guaranteed income from your annual spending estimate, then multiply the difference by 25.

What is the 4% rule and is it still valid?

The 4% rule states that you can withdraw 4% of your retirement portfolio in year one, then adjust that amount for inflation each subsequent year, with a high probability of not running out of money over a 30-year retirement. It comes from the Trinity Study, a 1998 paper by three Trinity University professors who tested withdrawal rates against historical US stock and bond market data going back to 1926. The rule remains widely used, though some researchers argue that current low bond yields and high valuations warrant a more conservative 3–3.5% rate — especially for longer retirements. Many financial planners treat 4% as a starting point and adjust based on individual circumstances, not a hard rule.

How much should I save for retirement each month?

A common rule of thumb is to save 15% of your gross income for retirement, including any employer match. This is designed for someone who starts saving at 25 and retires at 65 on roughly 70% of their pre-retirement income. If you start later, you need to save a higher percentage to catch up. Use this calculator in reverse: enter your target retirement corpus, current savings, expected return, and retirement timeline — then adjust the monthly contribution slider until the projected corpus meets or exceeds the required corpus. That number is your personal savings target.

What rate of return should I use for retirement projections?

The US stock market has returned approximately 10% per year on average before inflation over the long run. After accounting for inflation (historically around 3%), the real return is approximately 7%. For a conservative retirement projection, 6–7% is commonly used. For a moderate projection, 7–8% is typical. Running all three scenarios side by side — 6%, 8%, and 10% — gives you a more honest picture of the range of outcomes. The calculator lets you change the rate instantly and see how sensitive your corpus projection is to different return assumptions.

Does this calculator account for Social Security?

This calculator does not include Social Security as a separate input. The best way to incorporate it: estimate your expected monthly Social Security benefit (use the SSA My Account estimator), then subtract that monthly amount from your planned monthly retirement expenses before entering the figure into this calculator. For example, if you plan to spend $5,000 per month in retirement and expect $1,800 per month from Social Security, enter $3,200 as your monthly expense — that is the amount your portfolio needs to cover.