What is a retirement calculator?

A retirement calculator projects how your savings and contributions grow until a target age, and compares that nest egg to a “FIRE number” based on desired spending and a withdrawal rate (often 4%).

What is a FIRE number?

FIRE (Financial Independence, Retire Early) number ≈ annual spending ÷ withdrawal rate. At 4%, $40,000/year spending needs about $1,000,000. It’s a planning rule of thumb, not a guarantee.

What return rate should I use?

Many long-term planners use roughly 6–8% for a stock-heavy portfolio after fees, or lower if you expect a more conservative mix. Stress-test with a lower rate too.

The classic Trinity Study 4% guideline is a starting point for 30-year retirements in historical US data — not a promise. Sequence-of-returns risk, fees, and taxes matter. Adjust for your situation.

Is this retirement calculator free?

Yes — free, no signup. Use it to sketch timelines, then refine with inflation and contribution changes.

All tools

Retirement & FIRE Calculator

Free retirement calculator and FIRE number tool. Project portfolio growth to retirement age, estimate required savings, and see years to financial independence. No signup.

Project nest-egg size from savings, contributions, and returns — or reverse it: enter desired annual spending and a withdrawal rate to see your FIRE number. The classic “how much do I need?” answer with a clear timeline.

Your plan

Currency

Current savings ($)

Current age

Retirement age

Monthly contribution ($)

Expected annual return (%)

Many long-term planners use ~6–8% after fees for a stock-heavy portfolio.

Desired annual spending in retirement ($)

Withdrawal rate (%)

Classic “4% rule” starting point — not a guarantee.

Results

Projected nest egg (35 yrs)

$1,188,181.10

On track vs FIRE number

FIRE number: $1,000,000.00
Gap to FIRE: $0.00
You'll contribute: $235,000.00
Growth / interest: $953,181.10
Monthly needed to hit FIRE: $395.52

Educational estimate only — ignores taxes, sequence risk, and inflation unless you adjust inputs. Pair with an inflation calculator for real purchasing power.

What is a retirement / FIRE calculator?

People Google “how much do I need to retire?” and “FIRE calculator” for the same reason: a single dollar target beats vague hope. This tool projects your portfolio forward with contributions and returns, then compares it to a FIRE number based on spending and withdrawal rate.

The FIRE number formula

FIRE number = Annual spending ÷ Withdrawal rate

Example: $50,000/year spending at 4% → $50,000 ÷ 0.04 = $1,250,000. At 3.5% you’d need more; at 5% you’d need less (with more sustainability risk).

How to use this free retirement calculator

Enter ages, current savings, and monthly contribution.
Pick a return assumption you can defend (not hopium).
Set retirement spending and withdrawal rate.
Read projected nest egg vs FIRE number and “monthly needed.”
Adjust for inflation with the inflation calculator and growth detail with the compound growth projector.

401(k), ISA, and brokerage — same math

Whether you save in a US 401(k)/IRA, UK ISA, or taxable brokerage, the projection math is similar: starting balance + contributions + returns − eventual withdrawals. Tax wrappers change the after-tax result; this tool is the pre-tax planning sketch.

Common mistakes

Ignoring inflation: $40k today is not $40k in 30 years.
Assuming peak returns forever: Stress lower rates.
No emergency buffer: Retiring on a spreadsheet that assumes perfect markets.

Deeper walkthrough: retirement & FIRE number explained.

Frequently asked questions

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Educational calculator only — not financial, tax, or retirement advice. Past returns do not guarantee future results.

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Related guides

Basics8 min read

Retirement FIRE Number Explained (And the 4% Rule)

What a FIRE number is, how the 4% rule estimates portfolio needs, and how contribution math connects savings rate to financial independence.

Learn how to estimate a FIRE / retirement number with the 4% rule, what the rule gets wrong, and how to stress-test contributions with a retirement calculator.

Read guide