Coast FIRE Calculator

Coast FIRE (Coast Financial Independence, Retire Early) is the point at which your invested assets are large enough that, even with zero further contributions, the existing balance will compound to your full retirement target by retirement age. After hitting Coast FIRE you only need to earn enough to cover your day-to-day living expenses — your retirement is already funded.

First calculate your target retirement nest egg: annual expenses divided by your safe withdrawal rate (typically 4%, the 'Trinity Study' rule, which is equivalent to 25× annual expenses). Then divide that target by (1 + real return)^years to retirement. For example: $40,000 annual expenses ÷ 4% = $1,000,000 target. With 35 years until retirement and a 7% real return, your Coast FIRE number is $1,000,000 ÷ 1.07^35 = $93,663. That's how much you need invested today to coast.

Because expenses also rise with inflation. If you projected balances in nominal future dollars but expressed retirement expenses in today's dollars, the comparison would be apples-to-oranges. Using a real (after-inflation) return throughout keeps everything in today's purchasing power. The default 7% real return reflects the S&P 500's long-run nominal average (~10%) minus typical Canadian inflation (~3%).

All variants of FIRE (Financial Independence, Retire Early), but at different stages and lifestyles. Lean FIRE means retiring on a frugal budget (typically <$40K/yr). Fat FIRE means retiring with a generous budget ($100K+/yr). Coast FIRE is different: it's the point partway to either where you stop needing to save for retirement, but you still work to cover current expenses. Coast FIRE arrives years or decades before traditional retirement.

The 4% rule comes from the Trinity Study, which found that retirees who withdraw 4% of their initial portfolio annually (adjusted for inflation) historically had a high probability of not running out of money over a 30-year retirement. More recent research suggests 3.5-4% is still reasonable for a 30-year horizon, but longer retirements may need a more conservative rate. The calculator defaults to 4% but lets you adjust to your comfort level.

You can, but most people don't. Continuing to save past Coast FIRE accelerates your real retirement date or expands your lifestyle in retirement. Coast FIRE is a planning milestone — proof that retirement is mathematically secure — not a hard instruction to stop saving. Many people choose to keep contributing while shifting their working-income priorities (lower-stress job, more meaningful work, sabbatical years).

Most Canadian Coast FIRE plans rely on the same tax-sheltered accounts that make compounding hit hardest: TFSA, RRSP, and FHSA. Investment growth inside these accounts is sheltered from annual tax, which is what makes the long-horizon compounding math actually work. If your assumption is a 7% real return, that assumes the growth is happening inside a registered account; in a non-registered account at a 30% marginal rate, annual tax drag would reduce the effective real return by roughly your marginal rate applied to each year's yield.