How it works
Coast FIRE is the most liberating milestone most savers never hear about: the point where your invested savings, left untouched and never added to again, will still grow to your full retirement number by your target age. Past it, you no longer need to save another rupee or dollar for retirement — you only need to cover current living costs, which is a far easier bar and the source of the 'coast'. The calculator works it backwards. It finds your full FIRE number from spending and withdrawal rate, discounts that back to today over your years to retirement at your return rate, and the result is your Coast FIRE number — the savings that makes compounding do the rest. Compare it to what you have. A 30-year-old targeting $1.2 million at 60, at 7%, needs only about $157,000 today; already having $90,000 leaves a gap of $67,000 to close, after which saving for retirement is finished. That is the power of the milestone: it converts an intimidating thirty-year goal into a near-term one, and it is why the early years of saving matter out of all proportion to their size.
Formula
Coast FIRE = full FIRE number / (1 + return)^years | full FIRE = spending / withdrawal rate
Tips
- Coast FIRE means growth alone finishes the job — you only cover current costs after it.
- The earlier you hit it, the smaller the number, because compounding has longer to run.
- A negative gap means you have arrived; new savings now only pull the date earlier.
- Use 7% to keep the target in today's purchasing power.
- It converts a 30-year goal into a near-term one — the early savings do the heavy lifting.
Frequently asked questions
- What is Coast FIRE?
- The point where your current savings, never added to again, will still grow to your full retirement number by your target age. Past it you only need to cover living costs — retirement saving is effectively done, and you coast on compounding.
- How is the Coast FIRE number calculated?
- Find the full FIRE number (annual spending divided by withdrawal rate), then discount it back to today over your years to retirement at your return rate. A 30-year-old needing $1.2 million at 60 needs only about $157,000 today at 7%.
- What does a negative gap mean?
- You have already reached Coast FIRE — your current savings exceed the number needed for growth alone to hit your goal. Any further saving now simply pulls your retirement date earlier or makes it more secure; it is no longer required.
- How is Coast FIRE different from Barista FIRE?
- They are cousins. Coast FIRE means you stop saving but keep working to cover living costs. Barista FIRE is similar but assumes part-time work covers some costs while savings cover the rest. Both rest on the same insight: once compounding is doing the heavy lifting, the pressure comes off.
- Why does hitting it early matter so much?
- Because the number shrinks the further compounding has to run. The same retirement goal needs far less saved at 25 than at 40. Early savings are the most productive money you will ever invest, which is why the first years of a career are so decisive.