FIRE Number Calculator

What your FIRE number actually is

FIRE stands for Financial Independence, Retire Early. The idea is simple: save and invest aggressively enough that your portfolio can cover your spending, making paid work optional. Your FIRE number is the portfolio size where that flips from goal to reality, and the standard formula is elegantly short: annual expenses multiplied by 25.

That 25x comes from the 4% rule. Financial planner William Bengen first crunched the numbers in 1994, testing decades of US market data to find a withdrawal rate that survived every historical stretch, including the Great Depression. In 1998 three professors at Trinity University, Cooley, Hubbard and Walz, expanded on his work in what's now known as the Trinity Study, testing 50/50 stock-bond portfolios over rolling 30-year periods and finding a 4% inflation-adjusted withdrawal held up roughly 95% of the time. One divided by 4% is 25, so a portfolio 25 times your annual spending is built to sustain a 4% withdrawal rate indefinitely. Spend $60,000 a year and your FIRE number is $1,500,000.

Does the 4% rule actually hold up in Australia?

Broadly yes, with a few caveats worth taking seriously. The Trinity Study only modelled 30-year retirements. If you retire at 40 or 45, you're planning for 40 to 50 years, and the odds of a 4% withdrawal surviving that much longer stretch drop. Morningstar Australia's own research suggests a safe withdrawal rate closer to 3.5 to 3.8% for Australians, particularly those with a longer time horizon. At 3.5%, your FIRE number becomes annual expenses times roughly 28.6, so that same $60,000 a year now points to about $1.72 million rather than $1.5 million.

The ASX also behaves differently to the US market it was originally modelled on. Since 2000 it's delivered a total return of around 8.1% a year, split roughly evenly between capital growth and dividend yield, and Australian investors get franking credits on top of those dividends. Tax matters too: super withdrawals are tax-free after 60, which is a genuine edge over most overseas systems, but a non-super portfolio is taxed at your marginal rate (minus the 50% CGT discount on assets held over 12 months), so your effective spendable withdrawal rate outside super is a bit lower than the headline number suggests. Plenty of Australian FIRE planners settle on 3.5% as their working number for exactly this reason, it's more conservative, and more appropriate if you're retiring well before you can touch super.

The different flavours of FIRE

Not all FIRE looks the same. Here's roughly what each variant means in Australian dollars, and how the number shifts depending on whether you use a 4% or 3.5% withdrawal rate. See the full breakdown in our guide to the types of FIRE.

The ASFA Retirement Standard puts a "comfortable" retirement at around $55,923 a year for a single person and $78,566 for a couple, both assuming you own your home outright, which lands squarely in Regular FIRE territory. Coast FIRE and Barista FIRE work differently again. Coast FIRE is the amount you need invested right now so that compound growth alone, with no further contributions, carries you to your full FIRE number by a target age. Barista FIRE means you've got enough that part-time or casual work covers the gap between what your portfolio generates and what you actually spend, rather than your investments doing all the work.

A worked example: Alex, 32, Melbourne

Alex earns $110,000, spends $60,000 a year, has $80,000 invested outside super already, and puts away $3,500 a month ($42,000 a year). That's a savings rate north of 50%, which is excellent by any measure. At 4%, Alex's FIRE number is $1.5 million. Assuming a 7% real return, that works out to roughly 16 years, putting Alex on track for financial independence at about 48. Using the more conservative 3.5% target of $1.72 million instead pushes it out to around 17.5 years, or roughly age 50.

Bump the monthly contribution up to $4,500 and the timeline shortens by roughly two years on either target. That's the savings rate lever in action: it does double duty, growing the portfolio faster while also being money you don't need your future FIRE number to cover. Try both scenarios in the calculator above and watch how much a few hundred extra dollars a month actually moves the needle.

The Australian bridge strategy

This is the part most overseas FIRE content skips entirely. Super is locked until your preservation age, 60 for anyone born after 30 June 1964. If you retire well before that, you can't simply point at your super balance and call it done. Most serious Australian FIRE plans effectively run two pools: a bridge fund outside super, ETFs, shares, cash, sized to cover living expenses from early retirement until you can access super, and super itself, which takes over from preservation age onwards. If Alex retires at 48, that's a 12-year bridge to fund before super kicks in at 60.

The two pools can be built at the same time. Salary sacrificing into super grows the post-60 pool at a 15% contributions tax rather than your marginal rate, while everything you invest outside super builds the bridge. The employer Super Guarantee sits at 12% as of 1 July 2025, so that base is already growing without you lifting a finger, and the concessional contribution cap gives you room to add more on top if it makes sense for your tax situation. One thing worth flagging: preservation age has already risen from 55 to 60 over the past couple of decades. There's no guarantee it stops there, so it's worth building some buffer into your bridge rather than cutting it exactly to the year.

The risks that actually derail a FIRE plan

• Sequence of returns risk. A market crash in your first few years of retirement forces you to sell assets at depressed prices to fund living expenses, which permanently dents a portfolio's ability to recover. Holding a couple of years of expenses in cash helps you avoid selling into a downturn.
• Inflation. The RBA targets 2 to 3%, but healthcare and housing costs often run hotter than that for retirees, so $60,000 today won't buy the same lifestyle in 20 years.
• Lifestyle creep. Earning more tends to mean spending more, and a higher spending baseline means a bigger FIRE number. Track your real spending over 12 months before locking in a target.
• Preservation age moving again. It's already gone from 55 to 60. Build a bridge that can stretch past 60 rather than one that stops the day super becomes available.
• Longevity. Retire at 40 and live to 95, and your portfolio needs to last 55 years, well beyond the 30-year window the Trinity Study modelled. A more conservative withdrawal rate and some capacity to earn in early retirement both help.

The Age Pension is a possible safety net much later in life, but not something to build a plan around. Your FIRE number is a starting point for a conversation, not a finish line. Use the calculator to get oriented, then stress-test your assumptions with a financial adviser who understands early retirement in the Australian context.