Coast FIRE Basics
What Is Coast FIRE? Reaching Your Coast FI Number
A practical introduction to the point where your existing investments may be able to grow toward a retirement target on their own.
Ethan ColeEditorial contributor
Quick answer
What this article explains
Coast FIRE is a planning milestone: you have invested enough that, under a chosen set of long-term assumptions, your portfolio may grow to a retirement target without additional retirement contributions. It is an estimate, not a promise that you can stop working or saving.
The core idea behind Coast FIRE
A Coast FIRE number is the amount you would need invested today for compound growth to potentially reach your retirement portfolio target by your chosen retirement age. The calculation starts with the retirement spending you want to support, then works backward through time and an assumed inflation-adjusted return.
The idea does not decide how much you should spend, invest, or withdraw. It gives you a transparent way to compare a current plan with your own retirement timeline.
How it differs from traditional FIRE
Traditional FIRE generally describes having a portfolio intended to fund retirement spending now. Coast FIRE describes an earlier milestone: the portfolio is not yet your retirement target, but it may have enough time to grow toward it.
That distinction matters because employment income, healthcare, taxes, market returns, and lifestyle choices still affect any decision to reduce work or contributions.
What to check before changing savings
Use a Coast FIRE estimate as one input in a broader plan. Revisit your spending assumptions, your target age, the investments included in the calculation, and the risks that the calculator does not model.
- Keep a separate emergency fund and near-term cash needs outside the retirement projection.
- Consider taxes, fees, insurance, debt, and possible changes in income or spending.
- Review your assumptions periodically rather than relying on one calculation indefinitely.
Try the Coast FIRE Calculator
Compare your own retirement spending, timeline, savings, return, and inflation assumptions in a private browser-based estimate.
Common questions
Does Coast FIRE mean I can retire now?
No. It describes a projected future milestone, not an immediate retirement recommendation.
Do I have to stop contributing once I reach Coast FIRE?
No. Continuing to save can add flexibility and may help account for outcomes that differ from your assumptions.
Sources and further reading
These links provide general background. They do not validate any individual projection or replace professional advice.
