FIRE calculator

What financial independence really requires

Financial independence - the FI in FIRE, Financial Independence Retire Early - is reached when your investments can cover your spending without a paycheck. The target, your FIRE number, is simply your annual spending divided by a safe withdrawal rate. At the classic 4% rate that means 25 times your annual spending invested. This FIRE calculator projects your portfolio forward and tells you the age you reach that number.

Worked example

A 35-year-old with $400,000 invested, adding $60,000 a year, planning to spend $135,000 in retirement, at a 4% withdrawal rate and a 5% real return:

• FIRE number: $135,000 ÷ 4% = $3,375,000
• On track today: $400,000 ÷ $3,375,000 = about 12% of the way there
• Financial independence at: roughly age 57 (about 22 years out)

Change any input and the date moves - which makes the calculator a fast way to see what actually shortens the path.

The two levers that move the date most

• Your savings rate. Because the FIRE number is a multiple of spending, every dollar you don’t spend both lowers the target and raises what you invest. A higher savings rate is the single biggest accelerator.
• Your spending. At a 4% rate, cutting $1 of annual spending lowers your FIRE number by $25. This is why high earners with lifestyle creep can be out-paced by people who earn less but spend far less.

Coast FIRE: the milestone before the finish line

Coast FIRE is the amount you would need invested today so that, with no further saving, it compounds to your full FIRE number by traditional retirement age. Once you hit your Coast number, you can stop contributing and just cover current expenses - the existing portfolio “coasts” the rest of the way. It is a powerful psychological and practical checkpoint well before full FI.

How to read the result

The projection uses a smooth average real (inflation-adjusted) return, so the numbers are in today’s dollars. Two cautions:

• Sequence-of-returns risk. A bad run early in retirement is the main threat to any withdrawal plan; a smooth average understates that risk, so treat the date as a planning estimate.
• Taxes. The model does not subtract taxes on withdrawals. A complete plan accounts for where the money sits (Roth versus pre-tax versus taxable) and the tax on drawing it down.

Common mistakes

• Using an optimistic withdrawal rate; many early retirees prefer 3.25-3.5%.
• Forgetting that spending drives the target far more than income does.
• Ignoring taxes and health-insurance costs in early retirement.

To build the tax-free side of your retirement, see the Roth conversion calculator and the mega backdoor Roth calculator; your savings rate is the single metric that moves the date most.