Your numbers
Final balance
$650,568
You contributed
$185,000
Interest earned
$465,568
Year-by-year growth
Show the mathExpand →
Two compounding streams added together, compounded monthly:
balance = P·(1 + r/12)n + PMT·[((1 + r/12)n − 1) / (r/12)]
P = starting amount · PMT = monthly contribution · r = annual return · n = total months (years × 12).
Assumes same rate every year, monthly contribution at month-end, no taxes/fees/withdrawals. Real markets are lumpier.
How this calculator runs the math
Annuity-due compounding, monthly
We compound your balance month-by-month using the standard future-value-of-an-annuity formula — not a simple-interest approximation.
Pick your own return assumption
7% is a reasonable real (inflation-adjusted) S&P average. 10% is the nominal long-run. Treasuries run 4–5%. You set it.
No taxes, no withdrawals
This projects pre-tax, contributions-only growth. Real results depend on account type (Roth, 401k, taxable) and whether you take any out.