FIRE Calculator: Your Real Financial Independence Number
The 25x rule (multiply your annual spending by 25 to get your FIRE number) is a starting point derived from William Bengen’s 1994 research on the 4% safe withdrawal rate. It ignores taxes on withdrawals and government benefits, and both can change your required portfolio size a lot.
If your $70,000 annual spending comes from a traditional RRSP or 401(k), you’re not withdrawing $70,000. You’re withdrawing $90,000-$100,000 and paying $20,000-$30,000 in income tax. That’s closer to 33x your after-tax spending, not 25x. On the other side, CPP and OAS at 65 can replace $15,000-$25,000 of annual withdrawals in later years, which reduces your required portfolio. A FIRE calculator has to model both.
cinder.fi uses tax engines for all 13 Canadian provinces and 50 US states. Enter your target retirement age, expected spending, current savings, and planned account structure, and it projects the year-by-year picture: the gap years before government benefits start, the tax cost of withdrawals from each account type, and the portfolio survival probability under different return scenarios.
What cinder.fi Adds
- Tax-aware withdrawals: your FIRE number depends on which accounts you draw from. cinder.fi models RRSP, TFSA, and non-registered (Canada) or Traditional IRA, Roth IRA, and taxable accounts (US) with the correct tax treatment for each.
- Gap year analysis: If you retire at 45 and CPP/OAS (or Social Security) doesn’t start until 65, those 20 years require more from your portfolio. cinder.fi models the transition and shows the effect of different benefit claiming ages.
- Coast FIRE calculation: Coast FIRE is the portfolio size at which you can stop contributing and the existing balance will grow to your full FIRE number by a target retirement age. cinder.fi shows your coast FIRE number alongside the full number.
- Monte Carlo stress testing: the 4% rule is based on historical US market data. cinder.fi runs 1,000+ simulations with randomized returns to show the probability your plan survives 30, 40, or 50 years, not just the average case.
- Any retirement age: most retirement calculators assume 60-65. cinder.fi supports any retirement age, including early retirement at 35 or 40.
- RRSP meltdown for FIRE: If you’re retiring early with a large RRSP, regular withdrawals in low-income years before CPP/OAS start can sharply reduce lifetime taxes. cinder.fi models this strategy automatically.
- Spending flexibility: model a two-phase retirement where spending is higher in early active years and lower later, or include one-time large expenses like property purchase or children’s education costs.
Find Your Number
Enter your spending, savings rate, and account structure, and cinder.fi calculates your FIRE number with full tax modeling instead of the 25x rule.