Financial · Live

Retirement,
on the back of an envelope.

A precise retirement-savings calculator. Project your nest egg from current age, retirement age, current savings, and monthly contributions; see the inflation-adjusted purchasing power; and translate the final balance into estimated monthly income using the 4% rule (or your own withdrawal rate).

How it worksReal-time

Inputs

Your plan

Current age

Retire at

Current savings$25,000

Monthly contribution$500

$/mo

Assumptions

Annual return7

Annual inflation

Withdrawal rate

%/yr

Years until retirement: 35 yr
Total contributions: $210,000.00
Investment growth: $953,181.10

Nest egg at retirement

age 65 · 35y away

$1,188,181

≈ $500,665.14 in today's dollars after inflation · ≈ $3,960.60/mo at 4% withdrawal

Today

$25,000.00

You contribute

$210,000.00

Investment grows

$953,181.10

Years until retirement

From age 30 to 65

Real (today's $)

$500,665.14

After 2.5% inflation

Monthly income

$3,960.60

At 4% safe withdrawal

Trajectory

Year by year

TodayContrib.Growth

Schedule

Year-by-year balance

35 years

Age	Contributions	Growth	Balance
30	$0.00	$0.00	$25,000.00
31	$6,000.00	$2,003.54	$33,003.54
32	$12,000.00	$4,585.67	$41,585.67
33	$18,000.00	$7,788.19	$50,788.19
34	$24,000.00	$11,655.97	$60,655.97
35	$30,000.00	$16,237.08	$71,237.08
36	$36,000.00	$21,583.11	$82,583.11
37	$42,000.00	$27,749.34	$94,749.34
38	$48,000.00	$34,795.07	$107,795.07
39	$54,000.00	$42,783.88	$121,783.88
40	$60,000.00	$51,783.94	$136,783.94
41	$66,000.00	$61,868.35	$152,868.35
42	$72,000.00	$73,115.51	$170,115.51
43	$78,000.00	$85,609.47	$188,609.47
44	$84,000.00	$99,440.35	$208,440.35
45	$90,000.00	$114,704.82	$229,704.82
46	$96,000.00	$131,506.49	$252,506.49
47	$102,000.00	$149,956.50	$276,956.50
48	$108,000.00	$170,174.00	$303,174.00
49	$114,000.00	$192,286.76	$331,286.76
50	$120,000.00	$216,431.80	$361,431.80
51	$126,000.00	$242,756.03	$393,756.03
52	$132,000.00	$271,416.98	$428,416.98
53	$138,000.00	$302,583.57	$465,583.57
54	$144,000.00	$336,436.93	$505,436.93
55	$150,000.00	$373,171.30	$548,171.30
56	$156,000.00	$412,994.94	$593,994.94
57	$162,000.00	$456,131.18	$643,131.18
58	$168,000.00	$502,819.47	$695,819.47
59	$174,000.00	$553,316.61	$752,316.61
60	$180,000.00	$607,897.93	$812,897.93
61	$186,000.00	$666,858.68	$877,858.68
62	$192,000.00	$730,515.45	$947,515.45
63	$198,000.00	$799,207.71	$1,022,207.71
64	$204,000.00	$873,299.49	$1,102,299.49
65	$210,000.00	$953,181.10	$1,188,181.10

Field guide

How a retirement projection actually works.

A retirement calculator is fundamentally three numbers running through the same equation: how much you have today, how much you add each month, and how long the money has to grow. The expected rate of return decides what compound interest does with all that, and inflation tells you how much the resulting pile is actually worth.

The accumulation formula

Two pieces, both standard time-value of money:

FV_lump = P · (1 + r/12)ⁿ
FV_contrib = PMT · [ ((1 + r/12)ⁿ − 1) / (r/12) ]
nestEgg = FV_lump + FV_contrib

P: lump sum already saved today
PMT: recurring monthly contribution
r: annual rate of return (decimal)
n: number of months until retirement

The first equation grows your existing savings; the second grows each future contribution from the day it's made. Add them together and you have your nest egg.

Why starting early matters more than saving more

Compound interest is multiplicative in time, additive in contribution. A 25-year-old contributing $200/mo until 65 at 7% ends with roughly $525,000. A 35-year-old contributing $400/mo until 65 at the same rate ends with about $489,000 — slightly less, despite putting in twice as many dollars per month. Time in the market is the asset; rates of return are the lever; the monthly contribution is just fuel. Start early, even small.

Realistic return assumptions

The S&P 500's nominal return since 1928 is about 10% per year; subtract roughly 2.5–3% for inflation and you get a real return of about 7%. That's the default in this calculator. A balanced 60/40 portfolio runs closer to 5–6% real; a bond-heavy portfolio nearer to 3–4% real. Don't plug in a 12% return: that's what your past best year felt like, not what the next 30 years will deliver.

Inflation: nominal vs real

$1,000,000 in 30 years is not the same $1,000,000 as today. To get the purchasing power, divide by cumulative inflation:

real = nominal / (1 + inflation)^years

At 2.5% inflation, $1M in 30 years buys about $477,000 worth of today's groceries and rent. The hero number above shows both: the nominal dollar amount in big amber, and the real (today's-dollars) value as the subtitle.

The 4% rule (and what it really says)

William Bengen's 1994 paper and the 1998 Trinity-study follow-up showed that, historically, a retiree could withdraw 4% of their initial portfolio in year one, then adjust that dollar amount for inflation each year thereafter, and have very high odds of the portfolio lasting 30 years. So a $1M nest egg supports roughly $40,000/yr, or $3,333/mo in withdrawals, adjusted upward for inflation each year.

More recent revisions (especially Bengen's own 2020 re-analysis) suggest 4.7–5% may be safe, while high-CAPE-ratio environments arguably warrant 3.5%. The withdrawal rate above defaults to 4% but is adjustable.

Worked example

Age 30, retire at 65, $25,000 already saved, $500/mo contribution, 7% nominal return, 2.5% inflation:

Months until retirement: 35 × 12 = 420
Lump-sum FV: $25,000 × 1.00583⁴²⁰ ≈ $290,500
Contribution FV: $500 × [(1.00583⁴²⁰ − 1) / 0.00583] ≈ $902,000
Nominal nest egg: ≈ $1,192,500
Real (today's $): $1,192,500 / 1.025³⁵ ≈ $504,500
4% withdrawal: ≈ $3,975/mo (in nominal future dollars)

Account types worth knowing

Traditional 401(k) / IRA: contributions are pre-tax (lower taxable income today), withdrawals are taxed as ordinary income in retirement.
Roth 401(k) / IRA: contributions are after-tax, withdrawals are tax-free. Math favors Roth when you expect higher future tax rates.
HSA (with an HDHP) — pre-tax in, tax-free out for medical, and after age 65 acts like a traditional IRA. Triple tax-advantaged.
Taxable brokerage: no tax break, but no contribution limits and no withdrawal age restrictions. Long-term capital gains are taxed at lower preferential rates.

What this calculator doesn't model

For clarity, the calculator deliberately stays focused. Not included:

Social Security: adds roughly $1,500–$3,500/mo for typical earners; the SSA's "estimate your benefit" tool is the right place to size this.
Sequence-of-returns risk: the order in which good and bad years happen matters at the start of withdrawal. Real-world simulations use Monte Carlo or historical bootstrapping.
Tax brackets in retirement: your marginal rate may differ then. Use the Income Tax calculator to check.
Healthcare costs: Fidelity estimates $165k+ per couple in retirement; not a uniform expense.
Required Minimum Distributions (RMDs) — start at age 73 for traditional accounts.

Disclaimer

This calculator is a planning tool, not financial advice. Markets vary, inflation varies, and your circumstances evolve. Use the projection as a directional check on whether you're saving in the right ballpark; revisit yearly and adjust contributions as your income grows.

FAQ

Frequently asked

How much do I need to retire?+

A common rule of thumb is 25× your annual expenses (the inverse of the 4% rule). If you'll spend $50,000/yr in retirement, target $1.25M. The number scales with the lifestyle you want, not with your income.

What's a realistic rate of return to assume?+

7% nominal is the historical real return of U.S. stocks since 1928 (about 10% nominal − 2.5–3% inflation). For a balanced portfolio, 5–6% real is more realistic; for bond-heavy, 3–4%. Don't plug in 10–12% — that's an unusually good past, not a typical future.

Should I use the 4% rule or something different?+

The 4% rule is conservative-historical: it survived every 30-year window since 1926 in the original study. Recent reanalyses suggest 4.7% may be safe for most retirees, while volatile or expensive markets warrant 3.5%. Start with 4% and adjust based on your risk tolerance and bond allocation.

Why is the inflation-adjusted number so much smaller?+

At 2.5% annual inflation, prices roughly double every 28 years. So a $1M nest egg in 30 years buys what about $477k buys today, still substantial, but not the seven-figure cushion the headline number suggests.

Do I really need to save this much?+

If your employer offers a 401(k) match, contribute at least enough to get the full match — that's a 50–100% instant return that's hard to beat. Beyond that, a common target is 15% of gross income (employee + match combined) for a comfortable retirement starting in your 20s or 30s.

What's the difference between traditional and Roth?+

Traditional contributions reduce taxable income today, withdrawals are taxed as ordinary income later. Roth contributions are post-tax, withdrawals are tax-free. Use Roth when you expect to be in a higher tax bracket in retirement (often the case for younger savers); use traditional when you expect a lower bracket later.

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