When can I retire? A FIRE calculator

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This calculator will tell you when you might achieve a FIRE-level of retirement savings, given your current spending vs. savings rate. It's pure math - doesn't take into account variations, inflation, changing expenses, extra social security, taxes or other factors. It's not advice and nobody can predict the future. But numbers can be very helpful. I used popular example interest rates, 4% withdrawl, 5% investment gains, but you can certainly change them.

Disclaimers:
  • I like math, but don't trust me to make major decisions. Consult your professional advisor and check all the numbers you can.
  • I do not save any numbers you type into this form. It's all you, all browser-side.
  • I am not a financial advisor and this is not advice.
  • Some say you should never take financial advice from someone who's still working. I'm working. I haven't tested this out at all! I use this as pure inspiration for how much I should be saving.
  example: 5000
  example: 1000
  example: 200000
  example: 5
  example: 4
 


Years until retirement:    


The math: Nper = Log((Pmt/Rate - FV) / (Pmt/Rate + PV)) / Log(1+Rate)
Where
  • Pmt = Monthly savings
  • Rate = periodic interest rate (annual rate / 12)
  • FV = annual expenses / withdrawl rate (what you need in the end)
  • PV = what you have now
You can also use the nper() function in a spreadsheet for this. The theory? The lower your spending, the less you need to retire, because your goal is to save up an amount that lets you withdraw your spending at the same rate your investments grow. To retire earlier you can either lower your spending OR increase your savings - the ratio is what matters.





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