Retirement
Retirement Calculator
Free retirement calculator, project your savings growth, monthly withdrawal amount, and inflation-adjusted purchasing power. Enter your current savings, contributions, and target retirement age for instant results.
How This Retirement Calculator Works
This calculator uses compound interest to project your retirement savings. Enter your current age, retirement age, existing savings, and monthly contributions. The calculator applies your expected annual return rate, then adjusts the result for inflation to show real purchasing power.
Compound Growth
Every dollar you contribute today earns returns that themselves earn returns. Over 35 years at 7%, each $100/month contribution grows to ~$175K, the power of compounding.
The 4% Rule
Withdraw 4% of your savings in year one, then adjust annually for inflation. Research suggests this sustains a 30-year retirement with low depletion risk across most market conditions.
Inflation Adjustment
At 3% inflation, $1M in 30 years is worth ~$412K in today's dollars. The calculator shows both nominal and inflation-adjusted values so you can plan in real terms.
Return Rate
Historically, a diversified stock portfolio returns 7–10% annually before inflation. Use 7% for pre-inflation or 4–5% post-inflation. Lower rates give conservative projections.
The Math Behind the Projection
The calculator runs two compound-interest formulas side by side, using a monthly rate (your annual return divided by 12) and the number of months between now and your retirement age. Your current savings grow as a lump sum: P × (1 + r)^n, where P is your current balance, r is the monthly rate, and n is the number of months.
Your monthly contributions grow as an ordinary annuity: PMT × ((1 + r)^n − 1) / r, which accounts for each contribution earning returns for a different length of time (a contribution made in year one compounds for decades, while one made the month before retirement barely compounds at all). Adding the two results together gives the total projected balance; subtracting your actual contributions from that total gives the interest earned, which is the growth attributable purely to compounding rather than to money you put in.
Where the 4% Rule Comes From
The monthly withdrawal figure is calculated as your projected total savings multiplied by 4%, divided by 12. This 4% figure traces back to financial planner William Bengen's 1994 research and the later Trinity Study, both of which tested historical market returns to find a withdrawal rate that a retirement portfolio could sustain for roughly 30 years without running out, even across periods that included major market downturns.
The rule is not a guarantee. It assumes a diversified stock-and-bond portfolio, a fixed inflation-adjusted withdrawal each year, and roughly a 30-year retirement horizon. More recent analysis has proposed rates ranging from about 3.3% (more conservative, accounting for lower expected future returns) up to 5% (for shorter retirement horizons). The biggest risk to any fixed withdrawal rate is sequence-of-returns risk: a market downturn in the first few years of retirement does far more damage than the same downturn happening later, because you are selling a larger share of your portfolio at depressed prices.
What This Calculator Doesn't Account For
This projection is a simplified model built for planning conversations, not a financial guarantee. It assumes a constant annual return and constant inflation rate every year, which real markets never deliver; actual returns vary year to year and the order of good and bad years matters (sequence-of-returns risk).
- Taxes on withdrawals (traditional 401k/IRA) or on growth (taxable brokerage accounts)
- Social Security or pension income, which supplements personal savings for most retirees
- Employer 401k matching, which effectively increases your contribution rate
- Healthcare costs, which typically rise faster than general inflation
- Changes in spending needs across retirement (often higher early on, lower later)