When to use
Use this when you want to know whether compounding alone could carry your current portfolio to your retirement target by retirement age.
Coast FIRE Calculator
See whether your current portfolio could grow to your retirement target without additional contributions.
No login required. Inputs auto-save to your browser on this device.
What this is not
This is a simplified planning calculator. It does not fully model taxes, fees, inflation uncertainty, or market volatility.
How to Use This Calculator (3 Steps)
- Choose target mode: expense mode for SWR-based planning, or asset mode for a fixed retirement target.
- Enter your age, current portfolio, and expected long-run real return.
- Calculate your coast number and compare it with your current portfolio.
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Progress to coast: -
Coast number
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Current portfolio
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Gap remaining
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Target assets
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Years to retirement
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Return assumption
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What this means
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Projected Growth to Retirement
This chart compares two paths: if you stop contributing now, and if you keep contributing at your current pace.
If you stop contributing now
If you keep contributing
Coast number
Retirement target
Estimated years to coast
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Estimated age at coast
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If you keep contributing
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What these numbers mean
These estimates show when you may reach your required coast number if you keep contributing at your current pace.
Coast does not mean full retirement. It means your portfolio may be large enough that future contributions are no longer required to reach your retirement target under these assumptions.
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Scenario Compare
| Scenario | Return | Coast Number | Status |
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Inputs Explained
- Current portfolio: Your current investable assets.
- Annual real return: A long-run expected average after inflation.
- Annual spending: Used in expense mode to estimate a retirement target.
- SWR: The withdrawal rate used to convert annual spending into target assets.
- Target assets: A direct retirement target in asset mode.
- Coast number: The amount needed today such that compounding alone could potentially carry you to your target by retirement age.
Assumptions and Limitations
- Returns are modeled as a stable long-run average for planning.
- Compounding is simplified and does not reflect year-to-year volatility.
- Taxes, fees, inflation uncertainty, and future spending changes are not fully modeled.
- Results are educational planning estimates, not guarantees.
- Saved values stay in browser storage on your device.
Worked Example
Example: Current age 35, retirement age 65, current portfolio 250,000, annual spending 60,000, SWR 4%, annual real return 5%.
Result: Target assets 1,500,000, coast number about 347,000, status not yet coast, gap about 97,000.
FAQ
Should I include home equity?
Use a consistent rule that matches your withdrawal plan. Many users exclude primary home equity.
Should I use nominal or real returns?
This calculator is simpler if you use real returns. That means your return assumption already accounts for inflation.
Does coast mean I should stop investing?
Not necessarily. It means your current portfolio may already be large enough to grow to your target under your assumptions. Many users still keep investing for a margin of safety.
How is this different from the FIRE Tracker?
The Coast FIRE Calculator asks whether you could stop contributing now and still reach your target by retirement age. The FIRE Tracker estimates your timeline given ongoing contributions.
Related Tools
Want to model continued contributions in more detail? Open FIRE Tracker.
Author: SimpleReturns Team
Last updated: 2026-03-09