Coast FIRE Calculator
Discount a future retirement portfolio target back to the present using an entered real return consistent with today’s-dollar spending. The current invested balance is compared with that one Coast target.
How to use the Coast FIRE Calculator
Enter current age, retirement age, current invested assets, desired annual spending, withdrawal-rate assumption, and expected annual real return.
Review nominal versus real values, taxes, fees, sequence risk, pension or Social Security, contribution changes, spending uncertainty, and withdrawal-rate limitations.
Read retirement portfolio target, Coast FIRE number today, and current amount above or below that number.
Formula
Retirement target = annual retirement spending ÷ withdrawal-rate assumption. Coast number today = retirement target ÷ (1 + return rate)^years until retirement.
Example
A $1,000,000 target in 20 years discounted at 5% real growth has a present coast number of about $376,889.
Assumptions and limitations
- Coast FIRE is a deterministic scenario, not a guarantee; market returns, inflation, spending, taxes, and retirement duration will vary.
- Coast FIRE Calculator treats the entered values as estimates and does not infer missing project, account, or personal details.
- Calculations retain working precision except where the cited method requires an intermediate rounding step; displayed values are then formatted separately. Source rules and dated rates must be rechecked when they change.
Sources
- U.S. Securities and Exchange Commission: Compound Interest CalculatorCompound-growth inputs and future-value concepts. Reviewed 2026-08-14.
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Frequently asked questions
How does the Coast FIRE Calculator work?
Retirement target = annual retirement spending ÷ withdrawal-rate assumption. Coast number today = retirement target ÷ (1 + return rate)^years until retirement.
What information should I enter in the Coast FIRE Calculator?
Enter current age, retirement age, current invested assets, desired annual spending, withdrawal-rate assumption, and expected annual real return, then verify nominal versus real values, taxes, fees, sequence risk, pension or Social Security, contribution changes, spending uncertainty, and withdrawal-rate limitations.
What should I verify before using this Coast FIRE Calculator result?
Coast FIRE is a deterministic scenario, not a guarantee; market returns, inflation, spending, taxes, and retirement duration will vary.
Reviewed 2026-08-14 · real-return-coast-v1 · content-2026-08-14 · Trusty Calculator Editorial Team