What's your number to retire early?
Calculate your FIRE number, Coast FIRE milestone, and how many years until financial independence. Use the budget tool to model your retirement spending — then see your portfolio's path in a year-by-year chart.
Enter your annual expenses and current portfolio to see your FIRE number and timeline.
Open the budget tool above and enter your spending to see a breakdown here.
Would your FIRE plan have survived history?
Most FIRE calculators assume a flat average return. Real retirements do not get averages — they get sequences, and retiring into a bad run can break a plan that looks safe on paper. This stress-test replays your plan through every real market window since 1957, the same engine behind our pension drawdown calculator and S&P 500 calculator.
What is the 'One More Year' effect?
Working one extra year stacks three tailwinds at once — more contributions paid in, more compounding on the pot, and fewer years of withdrawals to fund. Here is what each extra working year would have done to your plan's historical success rate, assuming your entered return and contributions continue during those years.
| Extra years worked | Starting pot | Historical success rate | Change |
|---|
- Your FIRE number is expenses ÷ withdrawal rate. At 4% that's 25× your annual spending, so £30,000 a year needs a £750,000 pot.
- Spending is the biggest lever. Cutting expenses lowers your target and frees more to invest — it works on both sides of the equation.
- Coast FIRE comes first. Once your pot can compound to the full number unaided, you only need to cover today's bills.
- Layer ISA then SIPP. The ISA (£20,000/yr, any-age access) bridges early retirement; the SIPP unlocks at 55, rising to 57 in April 2028.
- Sequence risk is the real danger. A crash just after you retire hurts most — stress-test your plan and keep a cash buffer.
What is FIRE and how do you calculate your number?
FIRE — Financial Independence, Retire Early — means investing enough that your portfolio out-earns your spending, making paid work optional. The "retire early" part is almost secondary; many adherents keep working after reaching independence, simply because they now choose to. The goal is freedom, not idleness.
The calculation at its heart is the 25× rule, derived from the 4% safe withdrawal rate. Need £30,000 a year and you need £750,000 invested. Historically — from over 70 years of US data in the 1994 Trinity Study — withdrawing 4% a year and raising it with inflation had a roughly 95–100% success rate over a 30-year retirement. Early retirees facing longer horizons often adopt a 3–3.5% rate (a 28–33× multiple) for extra safety.
The formula: FIRE Number = Annual Expenses ÷ Safe Withdrawal Rate
At 4% SWR: £30,000 ÷ 0.04 = £750,000. At 3.5% SWR: £30,000 ÷ 0.035 = £857,143.
Worked example: Maya is 35, wants £30,000 a year in retirement, and has a £50,000 pot she adds £1,000 a month to at a 7% return. Her FIRE number is £750,000, and this calculator shows she reaches it in about 20.4 years — at age 55. Her Coast FIRE figure (enough to coast to 65 with no more contributions) is around £98,500, a milestone she passes far sooner. Load the Standard FIRE preset or enter these numbers to reproduce it.
The most important variable here isn't your return or income — it's your annual expenses. Cutting spending both lowers your FIRE number and frees more to invest, which is why the budget tool on this page matters so much. If you have a workplace pension, routing contributions through salary sacrifice also cuts your tax and National Insurance, freeing up more to invest each month.
What are the four types of FIRE?
They're lifestyle variants of the same 25× maths, from frugal to luxurious. Each suits a different budget, risk tolerance and ambition:
| Type | Annual expenses | FIRE number (4% SWR) | Description |
|---|---|---|---|
| Lean FIRE | £15,000–£25,000 | £375k–£625k | Highly frugal lifestyle, often with geographic flexibility (lower cost areas) |
| Standard FIRE | £25,000–£45,000 | £625k–£1.1m | Comfortable middle-class lifestyle without major deprivations |
| Fat FIRE | £50,000–£100,000+ | £1.25m–£2.5m+ | Luxurious or high-cost lifestyle with travel, private schooling, etc. |
| Barista FIRE | Any | Reduced (partial coverage) | Portfolio covers part of expenses; part-time work covers the rest |
| Coast FIRE | Any | Grows to full FIRE by retirement age | Enough invested now to coast to full FIRE without more contributions |
What is Coast FIRE and how do you calculate it?
Coast FIRE is the amount invested today that will compound to your full FIRE number by retirement age with no further contributions. It's one of the most psychologically powerful milestones, because it asks a different question: how much do I need now so my portfolio can coast the rest of the way on its own?
The formula is: Coast FIRE = FIRE Number ÷ (1 + annual return)years to retirement
For example, if your FIRE number is £750,000, you expect 7% annual returns, and you have 25 years until retirement age 60: Coast FIRE = £750,000 ÷ (1.07)25 = £750,000 ÷ 5.43 = £138,200.
Once you hit Coast FIRE, you're in a fundamentally different position. You no longer need to save aggressively — you only need to earn enough to cover your living expenses. This unlocks the freedom to take lower-paid but more fulfilling work, reduce hours, or simply stop stressing about saving. Many people hit Coast FIRE years before hitting full FIRE, making it an important early victory to calculate and celebrate.
How does UK FIRE work with ISAs, SIPPs and the State Pension?
UK FIRE layers a tax-free ISA for early access with a tax-relieved SIPP for later, topped up by the State Pension from 67. Most FIRE content is US-centric, but these UK wrappers change the strategy significantly.
Why is the ISA the cornerstone of UK FIRE?
Because it grows tax-free and can be accessed at any age, unlike a pension. You can contribute up to £20,000 a year with no capital gains tax and no income tax on dividends, and withdraw whenever you like — ideal for funding the years between early retirement and pension access age. A globally diversified index fund inside an ISA is the most common UK FIRE vehicle.
How does a SIPP fit into a FIRE plan?
A SIPP is extraordinarily tax-efficient but you can't touch it until age 55, rising to 57 in April 2028. Basic-rate taxpayers get a 25% uplift (put in £800, the pension receives £1,000); higher-rate taxpayers can reclaim a further 25% via self-assessment, cutting the effective cost of a £1,000 contribution to £600. For someone retiring at 45 the SIPP is locked for over a decade, so it's part of a broader strategy, not the sole vehicle.
What's the best ISA-and-SIPP layering strategy?
Max the freely accessible ISA first, then add to the SIPP for the extra tax relief. In early retirement you live off ISA withdrawals until pension access age, then switch to the SIPP — minimising tax both while building wealth and while drawing it down.
How does the State Pension affect early retirement?
The full new State Pension is £12,548 a year (2026/27), paid from State Pension age (rising to 67 by 2028). You need 35 qualifying National Insurance years for the full amount and 10 for anything. It cuts the income your portfolio must generate once it starts, but retiring young means fewer NI years — so consider voluntary Class 3 contributions (about £957 a year in 2026/27) to fill gaps. A full State Pension is one of the best guaranteed-return "investments" available — and if you can afford to delay claiming it, deferring adds about 5.8% a year for life, as our State Pension deferral calculator shows.
What is the biggest risk to a FIRE plan?
Sequence-of-returns risk — retiring just before a major crash — is the single biggest danger. If your portfolio drops 40% in your first year of retirement while you keep withdrawing 4%, you sell depressed assets permanently and those shares can never recover for you. To see how a given withdrawal rate would have survived every real market sequence since 1957, stress-test your plan with our pension drawdown calculator.
The standard mitigation strategies include:
- Cash buffer: Keep 1–2 years of expenses in cash. In a downturn, draw from cash instead of selling equities, giving your portfolio time to recover.
- Flexible spending: Reduce withdrawals by 10–15% in bad market years. The combination of a lower SWR and spending flexibility makes portfolio failure near-impossible in most historical scenarios.
- Lower SWR: A 3–3.5% SWR is highly conservative and has a near-perfect historical record over 40–50 year periods.
- Part-time income: Even £500–£1,000/month from part-time work during a downturn dramatically reduces pressure on the portfolio.
How can you reach FIRE faster?
Why does your savings rate matter more than your income?
Because the share of income you invest sets the timeline more than the size of your salary. A household saving 50% of after-tax income can reach FIRE in approximately 17 years from scratch. At 70%, it's around 8.5 years. At 25%, it's over 40 years. Increasing income matters, but so does controlling the denominator. Many FIRE households maintain high savings rates by owning property outright (no rent or mortgage in retirement expenses), owning vehicles outright (no finance payments), and eliminating recurring subscription costs.
Why invest in low-cost global index funds?
Because costs compound just as returns do, and small fees quietly become large sums. A fund charging 0.1% annual fee versus one charging 1% makes a staggering difference over 20+ years — the difference can amount to hundreds of thousands of pounds on a large portfolio. Vanguard's FTSE All-World ETF (VWRL/VWRP), iShares' equivalent, and similar products give UK investors broad global diversification at costs of 0.10–0.22%. There is no evidence that actively managed funds outperform over long periods after costs; extensive academic research supports low-cost passive index investing for long-term wealth building.
How does asset location boost your returns?
By keeping the right assets in the right wrappers so less of your growth is taxed. Hold growth assets (equities) inside your ISA and SIPP. Hold any bonds or cash outside wrappers if your wrapper capacity is limited, since these generate less taxable income. Keep tax-inefficient assets (high-dividend funds, REITs) inside wrappers where dividends won't be taxed. Good asset location can add 0.5–1% per year of after-tax return without changing your investment strategy at all.
Why should you track your spending relentlessly?
Because your annual spend sets your FIRE number, and most first-time trackers find significant hidden "leakage". Most people who track their spending for the first time discover significant "leakage" — small recurring costs that are individually insignificant but collectively substantial. The budget tool on this calculator is a starting point. Dedicated tools like Money Dashboard, Emma, or YNAB give you a live picture of where money goes. Knowing your actual annual spending — not an estimate — is the foundation of an accurate FIRE number.
FIRE Calculator — FAQs
Your FIRE number is the total portfolio value you need to retire and live indefinitely off your investments. It's calculated as your annual expenses divided by your safe withdrawal rate. At the standard 4% SWR, the formula is: FIRE number = annual expenses × 25. So £30,000/year in expenses requires a £750,000 portfolio.
The 4% rule comes from the 1994 Trinity Study, which found a 4% annual withdrawal from a diversified portfolio had near-100% historical success over 30 years. For early retirees with 40–50+ year retirements, many UK FIRE practitioners use 3–3.5% for additional safety. The rule was based on US data, but globally diversified portfolios have similar historical characteristics. The greatest risk is sequence-of-returns — retiring just before a major crash. A cash buffer and spending flexibility mitigate this significantly.
Coast FIRE is the amount you need invested today so that it will compound to your full FIRE number by retirement age with no further contributions. Once you hit Coast FIRE, you only need to earn enough to cover current living expenses — the compounding takes care of the rest. It's calculated as: FIRE number ÷ (1 + annual return)years to retirement. It's an important psychological milestone often reached years before full FIRE.
These terms describe the retirement lifestyle you're targeting. Lean FIRE means retiring on a frugal budget (£15–25k/year UK). Standard FIRE means a comfortable lifestyle (£25–45k/year). Fat FIRE means a luxurious lifestyle (£50k+/year). Barista FIRE means semi-retiring — your portfolio covers most expenses but you work part-time to cover the rest, which dramatically reduces the required portfolio size. All use the same SWR formula; only the annual expenses input differs.
Both — in a layered strategy. Max your ISA first (£20,000/year, fully accessible at any age, all growth tax-free). Then use a SIPP for additional tax relief on contributions — basic-rate taxpayers receive 25% uplift; higher-rate taxpayers can claim a further 25% via self-assessment. The SIPP can't be accessed until age 55, rising to 57 in April 2028, so early retirees should ensure their ISA can bridge to pension access age. In retirement, draw from the ISA until pension access age, then switch to the SIPP.
Yes, significantly. The full new State Pension (£12,548/year in 2026/27) starts at State Pension age, rising to 67 by 2028. If you retire at 45, your portfolio must fund 100% of expenses for the gap years, then only the shortfall after State Pension income. This calculator lets you enter your expected State Pension to reduce your effective annual expenses from age 67. Note: retiring early means fewer NI qualifying years — consider making voluntary Class 3 NI contributions (about £957/year in 2026/27) to fill gaps and protect your State Pension entitlement.
For a globally diversified index fund, historical nominal returns have averaged 7–9% per year over long periods. In real (after-inflation) terms, approximately 5–7%. Most FIRE practitioners use 7% nominal as a conservative base case, or 5% real. Being conservative in your assumption gives you a margin of safety — if the market delivers more, you hit FIRE sooner. If you're heavy in UK equities (FTSE 100), be aware the FTSE has underperformed global indices significantly over the past 20 years.
Sequence-of-returns risk is the danger of retiring just before a major market crash. Selling investments at low prices early in retirement permanently damages your portfolio's ability to recover. The mitigations are: (1) keep 1–2 years of expenses in cash so you don't need to sell equities in a downturn, (2) be flexible with spending — reducing withdrawals by 10–15% in bad years dramatically improves portfolio survival, (3) use a conservative SWR of 3–3.5%, (4) consider maintaining some part-time income in early retirement as a buffer.
This calculator solves for years to FIRE using the compound interest formula. Given your current portfolio (P), monthly contribution (PMT), monthly return rate (r), and FIRE number (FV), the formula is: n = log((FV + PMT/r) / (P + PMT/r)) / log(1 + r), where n is in months. The biggest variables are your savings rate and investment return. Increasing monthly contributions and reducing annual expenses simultaneously produce the most dramatic reductions in time to FIRE.
Yes, though it requires meaningful sacrifice. The median UK household income after tax is around £35,000. To reach FIRE in 15–20 years on this income requires saving 40–60% of take-home pay — achievable, but demanding. Many UK FIRE households do it through a combination of owning their home outright (or moving to a low-cost area), living car-free or with one vehicle, cooking at home, and channelling nearly all investment returns into index funds. Dual-income households with controlled expenses can reach FIRE faster. It's worth noting that even partial progress — reaching Coast FIRE, reducing hours, or building a safety net — has significant life-changing value even if full early retirement isn't the goal.
The 4% rule was derived from 30-year US retirements. Early retirees may need their money to last 40-50 years, and in historical worst cases a 4% withdrawal rate has come close to failing even over 30. Stress-testing against real market sequences, and having flexibility to cut spending in bad years, matters more than any single rule.
Working one extra year helps three ways at once: one more year of contributions, one more year of growth, and one fewer year of withdrawals. Historically this can raise a plan's success rate meaningfully — our One More Year table shows the effect on your own numbers.
This calculator is for educational and informational purposes only. Results are based on the data you enter and mathematical modelling — they are not predictions or guarantees. Investment returns can go down as well as up. Past performance is not a guide to future results. The 4% rule is a historical guideline, not a guarantee of portfolio survival. Always consult a qualified financial adviser before making retirement or investment decisions.