The Future Value Formula
This calculator projects growth using compound interest applied monthly, combining both your existing balance and ongoing contributions:
Future Value = Current Balance × (1 + r)ⁿ + Monthly Contribution × [((1 + r)ⁿ − 1) ÷ r]
Where r is the monthly return rate (annual rate ÷ 12) and n is the total number of months.
How Much Should You Have Saved?
Common rules of thumb suggest aiming for savings equal to roughly 10-12 times your final annual salary by retirement age, though the right target depends heavily on your desired retirement lifestyle, expected Social Security or pension income, and how long you expect retirement to last.
Why Starting Early Matters So Much
Because returns compound on both your contributions and your prior growth, money invested earlier has dramatically more time to compound. Two savers contributing the same monthly amount, but starting 10 years apart, can end up with a significantly different final balance — the earlier starter often ends up with a much larger sum despite contributing the same total amount over their overlapping years.
Important Caveat
This projection assumes a constant annual return, which real investments never provide exactly — actual markets fluctuate year to year. Use a conservative estimated return (historically, diversified stock market returns have averaged around 7-10% annually before inflation over long periods, though individual results vary) and treat this as a planning estimate, not a guarantee.