What is Coast FIRE?
Coast FIRE is the point where you've invested enough that, left completely alone with no further contributions, ordinary compound growth carries your portfolio to a full FIRE number by your target retirement age. You still need to earn enough to cover today's living costs — you just don't need to save any more toward retirement. From that point on, every dollar you'd normally be investing is free to spend, or to put toward something else entirely.
How to use this calculator
Enter your current age and your target retirement age — both required here, since the whole calculation depends on how much time your portfolio has left to grow. Add your total annual spending (everything, including rent or mortgage), your total invested assets, and how much you invest each month. If part of your spending is a mortgage, add the monthly repayment and years remaining separately — the calculator accounts for it whether it's paid off before or after your target retirement age.
The calculator works out your coast number — what you'd need invested today to coast the rest of the way — and shows you two phases: the accumulation phase you're in now, and what happens once you reach it and stop contributing.
What is the 4% rule?
The 4% rule is the basis for working out how big a portfolio needs to be to support your retirement spending: divide your annual spending by 4% (or multiply by 25) to get a rough target. This calculator uses it to work out your full FIRE number at your target retirement age, then works backwards to figure out your coast number today.
Coast FIRE vs Regular FIRE
With Regular FIRE, you keep investing the whole way until your full number is reached. With Coast FIRE, you keep working and earning until your target retirement age — you just stop having to save. Every dollar you'd normally invest becomes yours to spend today, redirect toward a career change, or use to work fewer hours.
Frequently asked questions
What if I've already passed my coast number? The calculator will show you've already coasted — your current savings, left alone, are projected to grow past your full FIRE number by your target age without another dollar invested.
Do I need to invest anything once I coast? No — that's the point. You keep working to cover your living costs, but the retirement portfolio takes care of itself.
Is this the same as Barista FIRE? No. Barista FIRE uses part-time income to shrink the portfolio you need in the first place. Coast FIRE relies purely on time and growth to get an already-adequate portfolio the rest of the way.
What if I have a mortgage? Enter the monthly repayment and years remaining separately from your other spending. It's treated as a fixed nominal payment that doesn't rise with inflation, and drops off your required spending once it's paid off — whether that happens before or after your target retirement age.
Does this calculator account for tax? Yes, there's an optional tax slider on withdrawals, set to 0% by default. When it's above zero, the calculator shows how much of your retirement withdrawal you actually keep.