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Retirement Calculator

Project your retirement nest egg and estimate monthly income with the 4% rule.

Privacy: your files never leave your device. All processing happens locally in your browser.

How to use

  1. 1.Enter your current age and the age at which you plan to retire.
  2. 2.Enter how much you have saved today and how much you contribute each month.
  3. 3.Enter an expected annual return (for example, 7 for 7%), then read your projected nest egg, estimated monthly retirement income (4% rule), and total contributed instantly.

About Retirement Calculator

The Retirement Calculator projects how large your retirement nest egg could grow and estimates the monthly income it might support. Enter your current age, your target retirement age, how much you have saved today, how much you add each month, and an expected annual return. The tool instantly shows three numbers: your projected nest egg at retirement, an estimated monthly retirement income using the 4% rule, and the total you will have personally contributed. Everything runs locally in your browser, so nothing you type is uploaded.

What sets this apart from a generic savings calculator is that it is driven by age. Instead of asking "how many years," it derives the saving horizon from the gap between your current age and your retirement age — the months from now until you stop working. Your existing balance compounds monthly at the expected return, and each monthly contribution is added and compounded as an ordinary annuity (deposits at the end of each month). The growth math is the standard future-value formula: nest egg = current savings × (1 + r)ⁿ + monthly contribution × ((1 + r)ⁿ − 1) ÷ r, where r is the monthly return and n is the number of months until retirement.

The second headline number applies the 4% rule, popularized by the Trinity study. The idea is that in year one of retirement you can withdraw about 4% of your nest egg, adjusting for inflation thereafter, and have a strong historical chance of the money lasting roughly 30 years. This calculator translates that annual 4% into a monthly figure — nest egg × 0.04 ÷ 12 — so you can see, in today's terms, the ballpark income your savings might replace. It is a planning guideline, not a promise: real safe withdrawal rates shift with market returns, inflation, fees, taxes, and how long your retirement lasts.

Worked example: a 30-year-old with $50,000 saved, adding $500 a month at a 7% expected return until age 65, is projected to reach roughly $1.48 million, supporting about $4,900 a month under the 4% rule — while having contributed $260,000 of their own money. Change any input above and the projection updates immediately, so you can test how retiring a few years later, saving more each month, or assuming a more conservative return reshapes the outcome.

Because markets are volatile and returns are never guaranteed, treat the output as an illustration rather than a forecast. When you want to model a fixed savings horizon with flexible deposit frequency, use the savings calculator; to see pure compounding on a lump sum, use the compound interest calculator. These figures are estimates for general information only and are not financial advice.

Methodology & sources

The projected nest egg uses the future value of a lump sum plus the future value of an ordinary annuity (end-of-month contributions): nestEgg = currentSavings × (1 + r)ⁿ + monthlyContribution × ((1 + r)ⁿ − 1) ÷ r, where r = annualReturnPct ÷ 100 ÷ 12 and n = (retirementAge − currentAge) × 12; when r = 0 the contribution term reduces to monthlyContribution × n. Estimated monthly retirement income applies the 4% safe-withdrawal rule from the Trinity study: monthlyRetirementIncome = nestEgg × 0.04 ÷ 12. Total contributed = currentSavings + monthlyContribution × n. Assumptions: a constant expected annual return compounded monthly, level monthly contributions made at each month-end, no taxes, fees, or inflation adjustment, and the 4% rule as a fixed guideline rather than a dynamic withdrawal strategy. Retirement age must exceed current age; negative ages, savings, contributions, or returns are rejected. These estimates are for general information only and are not financial advice — verify figures with a licensed professional.

Frequently asked questions

How is my retirement nest egg calculated?
Your current savings compounds each month at your expected return, and every monthly contribution is added and compounded as an ordinary annuity (deposits at month-end). The formula is nest egg = current savings × (1 + r)ⁿ + monthly contribution × ((1 + r)ⁿ − 1) ÷ r, where r is the monthly return (annual return ÷ 12) and n is the number of months from your current age to your retirement age.
What is the 4% rule for retirement income?
The 4% rule, from the Trinity study, suggests you can withdraw about 4% of your nest egg in the first year of retirement — adjusting for inflation afterward — with a strong historical chance the money lasts around 30 years. This calculator converts that to a monthly figure as nest egg × 0.04 ÷ 12. It is a widely cited guideline, not a guarantee, and your safe withdrawal amount will vary with returns, inflation, fees, and retirement length.
How is this different from a savings calculator?
A savings calculator asks for a fixed number of years and a deposit frequency. This retirement calculator is age-driven — it derives your saving horizon from the gap between your current and retirement ages — and it adds a retirement-income estimate using the 4% safe-withdrawal rule, which a general savings calculator does not provide.

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