SuperCalc

Retirement Calculator

Retirement is a two-act story: 30+ years of building a corpus, then 30+ years of drawing on it. Most calculators handle one or the other. This one handles both — with separate return rates for build and spend phases (the 'glide path'), inflation that grows withdrawals to maintain real spending, and a clear answer to the question that matters: will your money outlast you?

Wealth planner

Wealth Projection

Project where your money goes — building it up, drawing it down, or both across your full timeline.

$

Often $0 — just start from your contribution

% / yr
Build phase

Years you contribute. Money grows on contributions plus prior balance.

$
years
% / yr

Common: 5–10% as your income grows. 0 to keep flat.

Spend phase

Retirement years. Corpus keeps earning returns while you withdraw.

$
years
% / yr

Defaults to 3% (inflation).

% / yr

Defaults to 8% (build rate). Lower it (e.g. 6%) for a conservative portfolio.

Inflation (optional)

Grows your spend-phase withdrawal each year, and shows what your future numbers feel like in today's money.

% / yr

0 to ignore

Your $5K/mo lifestyle today, projected forward:
Year 5
$5.8K/mo
Year 10
$6.7K/mo
Year 20
$9K/mo
Y30 (at retirement)
$12.1K/mo
Your projection
Final balance
—
Contributed
—
Total drawn
—
Multiplier
—

How it works

During the build phase, you contribute monthly. Your money compounds at the build-phase return rate (typically 8–10% for an equity-heavy portfolio). Optionally, your contribution grows each year by a step-up percentage to model salary growth — 3% is a conservative real-wage assumption.

At retirement, your portfolio shifts to a more conservative allocation (the glide path). The retirement return rate is typically 2–3% lower than the build rate — more bonds, fewer stocks, less volatility. Use the 'Return in retirement' field to model this.

During the spend phase, you draw a monthly amount expressed in today's money. The calculator inflates it to the year you actually retire, then continues growing the withdrawal each year by the inflation rate so your real spending power is preserved.

The 4% rule says you can withdraw 4% of your starting corpus annually (adjusted for inflation) and have a high probability of lasting 30 years. The calculator surfaces your withdrawal rate as one of the four insight tiles — under 4–4.5% is the sustainability zone for long horizons.

FAQ

How much should I save for retirement?
A common rule of thumb: save enough to draw 4% of your retirement corpus annually for living expenses. So if you want $80k/year in retirement (in today's money), aim for a $2M corpus. The exact number depends on your spending, social security, and other income sources. Use the calculator to work backward from your target.
What's the 4% rule?
The 4% rule, from Bengen's 1994 study, says you can withdraw 4% of your initial retirement portfolio in year 1, then adjust that dollar amount upward for inflation each year, and have a 95%+ chance of the portfolio surviving 30 years (based on historical US data). It's a starting point — your withdrawal rate appears in the calculator's insight tiles.
What's a glide path?
A glide path is the gradual shift from aggressive (stock-heavy) to conservative (bond-heavy) allocation as you approach and enter retirement. Aggressive portfolios return more long-term but have bigger drawdowns — fine when you're 30, scary when you're 70. The 'Return in retirement' field lets you set a lower return rate (e.g., 5–6%) for the spend phase to model this.
Should I include 401(k) employer match?
Yes — if you're contributing $500/mo and your employer matches 50%, your effective monthly contribution is $750. Just enter the combined amount in 'Monthly contribution.' The calculator doesn't model tax impact (pre-tax 401(k) vs. Roth) — that's a separate optimization.
How does inflation affect retirement planning?
Inflation is the single biggest threat to retirement. At 3% annual inflation, your $1M retirement corpus has the buying power of about $412k after 30 years. The calculator handles this two ways: (1) shows your future value in today's money via the 'in your pocket today' note, (2) grows your withdrawals each year so your real spending power holds steady.
What about Social Security or pension income?
This calculator focuses on the corpus you control. Social Security and pensions reduce the corpus you need. If you expect $2k/mo from Social Security, you can subtract that from your target monthly retirement spending — only the remainder needs to come from your savings.

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