Calculator
Time to Freedom (FIRE) Calculator
Find the exact age you can stop working. Enter your savings, income and expenses — we'll calculate your FI number, when you'll hit it, and how your savings rate changes everything.
You today
Pensions, ISAs, brokerage, index funds — anything earning a market return. Exclude your home and emergency cash.
Income & spending
After tax. The actual money landing in your account each month.
Everything you spend in a typical month — rent, food, transport, fun.
Assumptions
Real return (after inflation). 7% is the long-run global stock-market average.
4% is the standard rule (Trinity study). Lower means more cushion.
All maths runs locally in your browser. Nothing is saved.
Milestones
FI number = annual expenses ÷ withdrawal rate. At 4% that's 25× your yearly spend. Once your invested portfolio reaches that figure, the returns alone can cover your life — work becomes optional.
How the FIRE calculator works
FIRE — Financial Independence, Retire Early — is the point at which your invested portfolio is large enough that withdrawals at a safe rate cover your annual living expenses indefinitely. The classic target is 25× your yearly spend, derived from the 4% safe withdrawal rule (Trinity Study, 1998).
This calculator projects your portfolio month by month using your current balance, monthly contributions, expected real return, and target expenses. It tells you when (and at what age) you cross your FI number, and shows milestones along the way.
The formula
FI number = annual expenses ÷ withdrawal rate
At a 4% withdrawal rate, that's 25× annual expenses. At 3.5% (more conservative), it's ~28.5×. Returns are entered as real (after inflation) so the FI number stays in today's money.
Worked example
Alex is 32, has £40k invested, contributes £1,500/month, expects 5% real returns, and spends £30k/year. FI number = £30k × 25 = £750,000.
Projecting forward, Alex hits £750k at roughly age 49 — around 17 years. Bumping contributions to £2,000/month brings that down to about age 46. The savings rate, more than the return, drives the timeline.
Frequently asked questions
What is FIRE?
FIRE stands for Financial Independence, Retire Early. It means accumulating enough invested assets that withdrawals at a safe rate cover your annual expenses, making paid work optional.
What is the 4% rule?
The 4% rule, from the Trinity Study, suggests that withdrawing 4% of a diversified portfolio in year one — adjusted for inflation thereafter — has historically lasted 30+ years. So your FI number is roughly 25× your annual expenses.
How important is savings rate?
Hugely. Mr Money Mustache's classic table shows: a 10% savings rate takes ~51 years to FI, 25% takes ~32 years, 50% takes ~17 years, and 75% takes ~7 years. Savings rate dominates returns over typical FIRE horizons.
What return should I assume?
Use a real (after-inflation) return. A globally diversified equity portfolio has historically delivered ~5–7% real, but past performance isn't guaranteed. Many FIRE planners use 4–5% to stay conservative.
What's Lean FIRE, Fat FIRE, Coast FIRE?
Lean FIRE = retiring on a frugal budget (e.g. £20k/year). Fat FIRE = retiring on a generous budget (£60k+/year). Coast FIRE = your portfolio is large enough to grow into your FI number without further contributions — you only need to cover current expenses.
Does this account for tax in retirement?
The calculator works in pre-tax expense terms. If your withdrawals will be taxed (e.g. from a SIPP or 401k), increase your annual expenses target to cover the gross amount needed.