Retirement Calculator

The Formula: How Retirement Projections Are Calculated

Your projected balance combines two pieces of compound-interest math: the future value of what you already have, plus the future value of a stream of ongoing contributions.

Future Value = PV × (1 + r)^n  +  PMT × [ ((1 + r)^n − 1) / r ]

Where:
  PV  = current savings (present value)
  PMT = contribution per period
  r   = periodic return rate (annual rate ÷ periods per year)
  n   = total number of periods until retirement

Worked example 1 — the mid-career saver. Age 35, retiring at 65 (n = 30 years), with $50,000 saved, contributing $500/month, at a 7% annual return.

Monthly r = 0.07 / 12 = 0.005833 ,  n = 360 months
Growth of savings: 50,000 × (1.005833)^360 ≈ $405,000
Growth of contributions: 500 × [((1.005833)^360 − 1)/0.005833] ≈ $610,000
Projected balance ≈ $1,015,000

Worked example 2 — the late starter. Age 50, retiring at 67 (n = 17 years), $120,000 saved, $1,000/month, 6% return.

Savings grow to: 120,000 × (1.005)^204 ≈ $332,000
Contributions grow to: 1,000 × [((1.005)^204 − 1)/0.005] ≈ $355,000
Projected balance ≈ $687,000

Worked example 3 — the FIRE saver. Age 28, retiring at 45 (n = 17 years), $30,000 saved, $3,000/month, 7% return.

Projected balance ≈ 30,000 × (1.005833)^204 + 3,000 × [((1.005833)^204 − 1)/0.005833]
≈ $98,000 + $1,110,000 ≈ $1,208,000

All three examples ignore inflation and taxes for clarity — the calculator can adjust for those separately.

The 4% Safe Withdrawal Rate — and Its Limits

Once you know your projected balance, the next question is how much you can pull out each year without running dry. The classic answer is the 4% safe withdrawal rate (SWR), derived from the 1994 Trinity/Bengen studies of historical U.S. market returns.

Annual safe withdrawal = Portfolio × 0.04
Target nest egg = Desired annual spending × 25

So a $1,000,000 portfolio supports roughly $40,000/year in year one, rising with inflation thereafter. Flip it around: if you want $60,000/year, you need $60,000 × 25 = $1.5 million.

Where 4% can break down

• •Early retirement. The 4% rule was modeled on a 30-year horizon. A FIRE retiree planning for 45–50 years should lean toward 3.25%–3.5% (a 28–31× multiple).
• •Sequence-of-returns risk. A market crash in your first few retirement years does far more damage than the same crash later, because you are selling shares while they are cheap.
• •Low starting yields. Some researchers argue for a more conservative 3.3% in high-valuation environments.

Rule of thumb: 25× your spending for a traditional retirement, 28–33× if you are retiring young.

Retirement Savings Benchmarks by Age

How much should you have saved by now? Financial firms like Fidelity publish salary-multiple benchmarks — targets expressed as a multiple of your annual income. They are rough guideposts, not guarantees, but they help you see whether you are ahead or behind.

2024–2025 contribution limits (U.S.)

If you are behind, the catch-up provisions after age 50 are a powerful lever — an extra $7,500/year in a 401(k) for 15 years can add well over $180,000 at a 6% return.

How to Interpret Your Savings Gap

The most actionable output of any retirement calculator is the savings gap — the difference between what you are on track to have and what you actually need.

Step-by-step

1. •Set your income goal. Decide the annual spending you want in retirement. A common starting point is 70–80% of pre-retirement income, since work costs and payroll taxes fall away.
2. •Subtract guaranteed income. Estimate Social Security or a pension. The average U.S. Social Security benefit in 2025 is roughly $1,980/month (~$23,700/year).
3. •Compute the portfolio need. Multiply the remaining spending by 25. If you want $60,000 and expect $23,700 from Social Security, you must self-fund $36,300 → $36,300 × 25 = $907,500.
4. •Compare to your projection. If the calculator projects $700,000, your gap is about $207,500.
5. •Close the gap. Raise contributions, delay retirement by a year or two (which both adds savings and shortens the drawdown), or trim target spending.

Closing a gap late is expensive but not hopeless: delaying retirement from 65 to 68 often does more than doubling your savings rate, because it adds three years of compounding and removes three years of withdrawals.

How to Use This Retirement Calculator

The calculator is built around five core inputs and three headline outputs.

Inputs

• •Current age — the starting point of the projection.
• •Retirement age — sets your accumulation horizon (n). Try both a traditional 65–67 and an early-retirement age to compare.
• •Current savings — the total in all retirement accounts (401(k), IRA, brokerage) today.
• •Monthly (or annual) contribution — include your own deferrals and any employer match. A 50% match on 6% of salary is real money.
• •Expected annual return — a diversified stock/bond portfolio has historically returned 6–8% nominal. Use a conservative figure if you want a safety margin, and consider entering an inflation-adjusted ~4–5% real return to see tomorrow's dollars in today's terms.

Outputs

1. •Projected retirement balance — your estimated nest egg at the retirement age.
2. •4% safe withdrawal — the sustainable annual income that balance supports.
3. •Savings gap / FIRE readiness — whether you hit your target and, for early retirees, your financial-independence number.

Adjust one variable at a time and watch the outputs move. This sensitivity testing is where the real insight lives — you will quickly see whether contributions, return, or timing is your biggest lever.

Strategies to Grow Your Retirement Savings

A projection is only as good as the behavior behind it. These strategies consistently move the needle.

• •Capture the full employer match first. It is an instant 50–100% return. Skipping it is leaving free salary on the table.
• •Automate and escalate. Set contributions to rise automatically 1% each year — most people never feel it, yet it can lift your ending balance by 25%+.
• •Prioritize tax-advantaged space. Fill your 401(k) match, then an IRA, then max the 401(k) before taxable investing.
• •Roth vs. traditional. Roth makes sense if you expect a higher tax bracket later; traditional if you want the deduction now. Many savers split the difference.
• •Mind fees. A 1% expense ratio versus 0.05% index fund can quietly erase 20–25% of your final balance over 30 years.
• •For FIRE seekers: push your savings rate, not just your return. At a 50% savings rate you can reach financial independence in roughly 17 years regardless of income; at 65% it drops to about 10.5 years.

Time in the market beats timing the market. Starting at 25 instead of 35 can double your final balance for the same monthly contribution.

Common Retirement Planning Mistakes to Avoid

Even careful savers stumble on a handful of predictable errors. Correcting them costs nothing but attention.

• •Ignoring inflation. A $1M balance sounds like plenty, but at 3% inflation its purchasing power halves in about 24 years. Always sanity-check goals in real dollars.
• •Assuming unrealistic returns. Plugging in 10–12% because "the stock market averages that" ignores inflation, fees, and bond allocation. 6–7% nominal is a sober planning number.
• •Forgetting healthcare and taxes. Retirees underestimate medical costs (a couple may need $300,000+ for healthcare) and forget that traditional 401(k)/IRA withdrawals are taxed as ordinary income.
• •Cashing out on job changes. Rolling a 401(k) into an IRA preserves compounding; cashing it out triggers taxes and a 10% penalty before 59½.
• •Applying 4% to a 50-year retirement. As covered above, early retirees need a lower withdrawal rate.
• •Set-and-forget. Revisit the plan annually. Raises, market swings, and life changes all shift your gap.

Correct these and your projection becomes a realistic roadmap rather than a comforting fiction.