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Retirement Calculator — Savings Projection & Monthly Income Estimate

Project your retirement savings with compound growth and monthly contributions. Estimate monthly income using the 4% rule and see real value in today's dollars.

What is this calculator?

This retirement calculator projects how much your savings will grow by retirement using compound interest on existing savings plus monthly contributions. It applies the 4% safe withdrawal rule to estimate monthly retirement income and adjusts for inflation to show real value in today's dollars.

Formula

FV_principal = currentSavings × (1 + r)^n FV_contributions = monthlyContribution × ((1+r)^n − 1) / r Projected Savings = FV_principal + FV_contributions Monthly Income = Projected Savings × 0.04 / 12 Real Value = Projected Savings / (1 + inflation)^years

Example

Age 30, retiring at 65, $50,000 saved, $500/month contribution, 7% return, 3% inflation: 35 years × 12 = 420 months. Monthly rate = 0.5833%. Projected ≈ $1,298,635. Monthly income ≈ $4,329. Real value today ≈ $460,000.

How to use

  1. 1Enter your current age, target retirement age, current savings, and monthly contribution amount.
  2. 2Adjust the expected annual return (default 7%) and inflation rate (default 3%) as needed.
  3. 3Click Calculate to see your projected retirement savings, total growth, estimated monthly income, and the real inflation-adjusted value.

Frequently Asked Questions

What is the 4% rule for retirement income?
The 4% rule, popularized by the Trinity Study, suggests withdrawing 4% of your retirement portfolio per year to make it last at least 30 years. The monthly income estimate in this calculator is projectedSavings × 0.04 / 12. For a $1,000,000 portfolio, that's $40,000/year or $3,333/month. The rule assumes a diversified stock/bond portfolio with historical market returns.
What annual return rate should I use?
A commonly used assumption for a diversified US stock/bond portfolio is 6–8% nominal return. The S&P 500 has averaged about 10% nominal and 7% real (inflation-adjusted) returns historically. This calculator defaults to 7%, which is a conservative estimate for a mixed portfolio. For bond-heavy portfolios, use 4–5%.
What does 'Real Value in Today's Dollars' mean?
Real value adjusts the projected savings for inflation to show what your nest egg will actually be worth in today's purchasing power. It is calculated as projectedSavings / (1 + inflationRate/100)^years. At 3% inflation over 30 years, $1M in future dollars is equivalent to about $412,000 today.
How are monthly contributions compounded?
Monthly contributions are treated as an ordinary annuity — each payment earns interest from the time it is made. The formula is FV = contribution × ((1+r)^n − 1) / r, where r is the monthly rate (annualReturn/12/100) and n is total months. This accurately models dollar-cost averaging into an investment account.
Does this include Social Security or pension income?
No. This calculator only projects savings growth from your personal contributions and existing savings. Social Security benefits, pension income, or other income sources are not included. For a full retirement income picture, add expected Social Security payments to the monthly income estimate shown here.

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