Coast FIRE is the point where your invested money is large enough that, left alone to compound, it will reach your retirement target without any further contributions. Once you hit your Coast FIRE number, you only need to cover your living expenses. You can stop saving for retirement entirely. This calculator tells you what that number is.
Frequently Asked Questions
Regular FIRE (Financial Independence, Retire Early) means saving enough that you can live off investment returns immediately. Coast FIRE is an earlier milestone: you have saved enough that compound growth will get you to your retirement number on its own. You still work, but only to cover current expenses, not to save more for retirement.
Your Coast FIRE number is the amount you need invested today so that compound growth over your remaining years to retirement reaches your target retirement corpus. It is calculated by working backwards from your retirement goal using present value discounting.
A common assumption is 7% real return (after inflation) for a diversified equity portfolio over the long term. Some use 10% as a nominal return before inflation. Being conservative with your assumed return gives you a safer, larger Coast FIRE number to aim for.
Once you hit your Coast FIRE number, you stop making additional retirement contributions and just let the invested amount grow on its own. You still work to pay for your current lifestyle. The investments are on autopilot heading toward your retirement target.
The maths works for any country. The currency, return rate assumptions, and retirement corpus target are yours to set. Indian investors typically use rupee amounts with 10-12% return assumptions. US investors might use 7% real returns. The formula does not change.
A SIP calculator tells you how much a series of monthly contributions will grow to. A Coast FIRE calculator works backwards: given a retirement goal and time horizon, what lump sum invested today is sufficient? It is about a one-time invested amount growing to a target, not ongoing contributions.