Coast FIRE Calculator FAQ

Coast FIRE is the point where your invested assets have grown enough that, even if you stop adding new money, compounding alone will grow your portfolio to your target retirement balance by your planned retirement age. The key insight is that early contributions do the heavy lifting—once you reach the coast number, you can reduce your savings rate or switch to a less demanding job while time and compound returns finish the job.

Yes. Switch to Household mode to plan with a shared portfolio, combined income streams, and one coast age based on the primary partner's timeline. The calculator uses the primary age as the projection clock and applies the same real return and withdrawal rate assumptions to the entire household balance.

Yes. Add the total value of all accounts earmarked for retirement as your invested assets. The calculator does not distinguish between tax-deferred, tax-free, or taxable accounts—it treats every dollar the same. If you want a more tax-aware picture, you can adjust your spending or withdrawal rate inputs to approximate after-tax outcomes.

Most spreadsheets and Reddit examples use the same core present-value math, but this calculator adds income offsets for pensions and Social Security, a year-by-year contribution projection with growth, a progress percentage, an earliest-coast-age search, and currency presets with country-specific inflation defaults. It also shows the gap between your projected retirement portfolio and your target so you can see whether you are on track or falling short.

Yes. The calculator ships with presets for USD, CAD, GBP, EUR, AUD, NZD, JPY, CHF, SGD, and HKD, plus a custom option. Each preset changes the currency symbol and sets a default inflation rate appropriate for that economy, which flows into the real return calculation automatically.

The coast age is the earliest year where your projected portfolio—including all future contributions up to that age—is large enough that compounding alone can reach your target by retirement. After that age, the calculator assumes you stop adding new money. In practice, many people keep contributing beyond their coast age to build a buffer against market volatility or to retire earlier.

Income streams that start on or before your retirement age reduce your effective retirement spending, which lowers the target portfolio you need. Income that starts after retirement is discounted back to retirement day using your real return and subtracted from the target. Adding guaranteed income always reduces the coast number and may bring your coast age earlier.