Savings: Coast FIRE calculator
Your core numbers: age, what you have invested, what you add each year, what you'll spend and when you want to retire. Every other system reads them from here, so you only enter them once.
About Coast FIRE
What is Coast FIRE?
Coast FIRE is the point where the money you've already invested would grow to your FIRE number by your retirement age, even if you never added another dollar. From then on, your pay only has to cover what you spend today.
How is the Coast FIRE age found?
Start with your FIRE number: what you'll spend each year in retirement, divided by a withdrawal rate that fits how long retirement lasts (4% for 30 years or less, sliding down to 3.25% for 60 years). For each age between now and retirement, the calculator works out how much would have to be invested for growth alone to reach that number. Your Coast FIRE age is the first age your balance, at the rate you save now, meets that amount.
Why is the answer a range of ages?
Nobody knows what markets will return. The calculator assumes 5% a year after inflation unless you change it, then works the answer out again at 2 points lower and 2 points higher, so you can see how much your age depends on the market.