Savings Duration Calculator
Model fixed-starting withdrawals month by month rather than dividing balance by spending and ignoring growth. The entered annual inflation rate increases the monthly withdrawal while return is applied to the balance.
How to use this calculator
Enter starting savings, starting monthly withdrawal, annual return, and annual inflation.
Review sequence risk, taxes, variable spending, market volatility, cash reserves, pensions, required distributions, and emergency needs.
Read duration, fully funded months and years, stopping balance, partial next withdrawal, shortfall, and sustainability flag.
Formula
Each month: apply annual return ÷ 12, then subtract the inflation-adjusted withdrawal. Stop after fully funded months; if the next withdrawal is partial, report its available amount and shortfall separately.
Worked example
$100 with $60 monthly withdrawals and zero return funds 1 full month, then reports a $40 partial next withdrawal and a $20 shortfall.
Assumptions and limits
- A non-depleting result requires monthly return to exceed withdrawal growth and the balance multiplied by that rate difference to cover the starting withdrawal; sequence risk, taxes, and fees are excluded.
- Savings Duration 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 Savings Duration Calculator work?
Each month: apply annual return ÷ 12, then subtract the inflation-adjusted withdrawal. Stop after fully funded months; if the next withdrawal is partial, report its available amount and shortfall separately.
What information should I enter in the Savings Duration Calculator?
Enter starting savings, starting monthly withdrawal, annual return, and annual inflation, then verify sequence risk, taxes, variable spending, market volatility, cash reserves, pensions, required distributions, and emergency needs.
What should I verify before using this Savings Duration Calculator result?
A non-depleting result requires monthly return to exceed withdrawal growth and the balance multiplied by that rate difference to cover the starting withdrawal; sequence risk, taxes, and fees are excluded.
Last updated 2026-08-25 · full-month-partial-withdrawal-v3 · content-2026-08-14 · Published by YunFanLabs