Calculate your Financial Independence, Retire Early (FIRE) target and how many years until you reach it.
This calculator provides estimates based on assumed growth rates. Investment returns are not guaranteed. The 4% withdrawal rule is a guideline, not a guarantee of sustainable income. Always consult a financial adviser.
FIRE (Financial Independence, Retire Early) is a movement focused on aggressive saving and investing to achieve financial independence much earlier than the traditional retirement age. The core idea is simple: save a large portion of your income, invest it wisely, and eventually your investment returns cover your living expenses indefinitely. The foundation of FIRE is the "4% rule," derived from the Trinity Study. This research found that withdrawing 4% of a diversified portfolio annually, adjusted for inflation, had a high probability of sustaining a 30-year retirement. Your FIRE number -- the total savings needed -- is therefore 25 times your annual expenses. If you spend GBP 25,000 per year, you need GBP 625,000. Your savings rate is the single most important variable. At a 50% savings rate with 7% annual returns, you can reach FIRE in roughly 17 years regardless of your income level. A higher savings rate works doubly -- you invest more each month while simultaneously proving you can live on less, reducing your FIRE number. The UK offers particular advantages for FIRE seekers. ISAs provide tax-free growth and withdrawals (GBP 20,000 annual allowance). Pensions offer tax relief on contributions. The State Pension provides a safety net from age 67. And the NHS means you do not need to budget for health insurance in retirement, unlike in the United States. This calculator computes your FIRE number, estimates how many years until you reach it, and shows Lean FIRE (frugal lifestyle), Fat FIRE (comfortable lifestyle), and Coast FIRE (the amount needed now to coast to traditional retirement) targets.
To calculate your path to FIRE: 1. Enter your annual income after tax. This is your total take-home pay after income tax and National Insurance. Include any regular after-tax income sources. 2. Enter your annual expenses. This is your total annual spending. Be honest and include everything: housing, food, transport, entertainment, insurance, and discretionary spending. Check your bank statements for an accurate figure. 3. Enter your current savings and investments. Include ISAs, pensions, taxable investment accounts, and any other invested assets. Do not include your emergency fund or your home (unless you plan to sell it to fund retirement). 4. Set the expected annual return. The default 7% represents a reasonable long-term return for a global equity portfolio before inflation. Adjust based on your risk tolerance and asset allocation. 5. Set the safe withdrawal rate. The default 4% is the standard FIRE assumption. Use 3.5% for a more conservative estimate or 3% if you plan a very early retirement (40+ years). 6. Review the results. Your FIRE number is the target pot. Years to FIRE shows how long at your current pace. The chart shows your projected balance growing towards the target.
The FIRE calculation combines several related concepts: FIRE Number = Annual Expenses / Withdrawal Rate For example: GBP 25,000 / 4% = GBP 625,000 Savings Rate = (Income - Expenses) / Income x 100 For example: (GBP 50,000 - GBP 25,000) / GBP 50,000 = 50% Years to FIRE: Simulated month by month with compound growth Each month: Balance = Balance x (1 + monthly return) + monthly savings Continue until balance reaches FIRE number Lean FIRE = 50% of annual expenses / withdrawal rate This covers only essential expenses for a frugal retirement Fat FIRE = 150% of annual expenses / withdrawal rate This allows for a more comfortable lifestyle with travel and luxuries Coast FIRE = FIRE Number / (1 + annual return)^30 This is how much you need invested today so that with zero additional savings, compound growth alone reaches your FIRE number by a traditional retirement age (assuming 30 years) Monthly Investment Needed: Solved algebraically using the future value of an annuity formula PMT = (FV - PV x (1+r)^n) / (((1+r)^n - 1) / r) where FV = FIRE number, PV = current savings, r = monthly return, n = months to FIRE
Inputs: Income: GBP 50,000, Expenses: GBP 25,000, Savings: GBP 50,000, Return: 7%, Withdrawal: 4%
Inputs: Income: GBP 50,000, Expenses: GBP 25,000, Savings: GBP 700,000, Return: 7%, Withdrawal: 4%
Inputs: Income: GBP 80,000, Expenses: GBP 32,000, Savings: GBP 100,000, Return: 7%, Withdrawal: 4%
The 4% rule was based on US market data from 1926-1995. Some researchers argue that for UK investors or for very long retirements (40+ years), a 3-3.5% withdrawal rate is more prudent. Others point to the UK State Pension as a safety net that effectively reduces the required withdrawal rate. A common UK FIRE strategy uses the "three pot" approach: pension pot (accessible from age 55/57), ISA pot (accessible anytime, tax-free), and a bridge pot (to cover expenses between early retirement and pension access age). This requires careful sequencing of withdrawals. The UK ISA allowance of GBP 20,000 per year is a powerful FIRE tool. A Stocks and Shares ISA provides tax-free growth and withdrawals, meaning your entire 4% withdrawal is tax-free. Over 15-20 years of maxing out your ISA, you can build a significant tax-free pot. Inflation is the FIRE seeker's biggest enemy. A 2% inflation rate means GBP 25,000 of expenses today becomes roughly GBP 37,000 in 20 years. Your FIRE number should ideally use inflation-adjusted return assumptions (typically 4-5% real return instead of 7% nominal). Coast FIRE is an appealing milestone for those who do not want to save aggressively forever. Once you reach your Coast FIRE number, you can switch to a lower-stress job that just covers current expenses without needing to save anything extra. The FIRE movement is not about extreme frugality for everyone. "Barista FIRE" means having enough investments to partially retire, working part-time for remaining expenses and social connection. The goal is having options, not necessarily stopping all work.