Coast FIRE is the point where what you have invested could grow to your retirement target on its own, without new contributions. After that, your income only has to cover your current spending.
The formula
Coast number = retirement target / (1 + real return) ^ years until retirement.
Real return means after inflation. This example uses 5%, which is an assumption, not a promise.
Example: a $1,000,000 target at 65
| Age now | Years to 65 | Coast number at 5% real |
|---|---|---|
| 30 | 35 | about $181,000 |
| 35 | 30 | about $231,000 |
| 40 | 25 | about $295,000 |
Each 5 years of delay adds a lot, because there is less time for growth to do the work.
Where the target comes from
A common starting point is 25 times your expected yearly spending in retirement (the 4% rule). $40,000 a year gives $1,000,000.
Cautions
- Returns are not steady. A lower real return (say 4%) raises the coast number noticeably.
- Many people keep contributing at least enough to get an employer match even after reaching it.
- Re-check every year; it is a moving estimate, not a finish line.
Free tools
- Coast FIRE calculator: https://smartbudgetsheets.surge.sh/calculators/coast-fire-calculator/?utm_source=mataroa
- FIRE calculator: https://smartbudgetsheets.surge.sh/calculators/fire-calculator/?utm_source=mataroa
- Retirement savings calculator: https://smartbudgetsheets.surge.sh/calculators/retirement-savings-calculator/?utm_source=mataroa
- Debt Payoff Planner, up to 8 debts (Payhip): https://payhip.com/b/PtBLU?utm_source=mataroa
- 42 free budget templates, pay what you want ($0 is fine): https://smartbudgetsheet.gumroad.com/l/ngpkrb?utm_source=mataroa
General information, not financial advice. Figures are rounded examples.