Coast FIRE Calculator

Coast FIRE means you have already invested enough that, without saving another dollar, compound growth alone will carry your portfolio to a full retirement number by traditional retirement age. Once you hit Coast FIRE, you only need to earn enough to cover current living expenses — every paycheck stops carrying your retirement on its back.

Take your combined annual retirement spending, divide by your safe withdrawal rate to get the household FIRE number, then discount it back by your expected real return for the years until retirement. Example: $72,000 spending at 4% is a $1.8M FIRE number; 25 years from retirement at a 4.4% real return, the couple coast number today is roughly $620,000 of combined invested assets.

This calculator assumes you retire together when the older partner reaches the retirement age you choose. That is the conservative convention — it gives your money fewer years to compound, so the coast number is higher. If you plan to retire at different times, run the calculation once per partner with their own age.

Regular FIRE asks when you can stop working entirely; Coast FIRE asks when you can stop saving. Coast FIRE numbers are much smaller because compounding does the remaining work over decades. Many couples use Coast FIRE as the first milestone — reach it, then downshift to lower-stress jobs that just cover the bills.

Yes. This calculator grows your money at the real return — expected investment return minus inflation — so you can enter retirement spending in today’s dollars and the answer stays honest in purchasing-power terms.