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 this 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.
Worked 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 limits
- 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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Verification
How this calculator is checked
Trust comes from reproducible evidence, not model confidence. You can inspect the formula, assumptions, worked example, and cited sources on this page.
- Versioned calculationFormula logic is kept separate from the interface and covered by automated registry and behavior checks.
- Cited evidenceSources linked for independent checking: 1.
- Transparent AI useAI may assist drafting or adversarial review. Agreement between models is not proof, and no human expert review is claimed unless a named reviewer is shown.
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.
Last updated 2026-08-25 · real-return-coast-v1 · content-2026-08-14 · Published by YunFanLabs