Compound growth
Project long-term returns from a starting amount plus recurring monthly contributions.
Inputs
Total contributed
$58,000.00
Investment growth
$86,572.72
Projected balance
After 20 years
$144,572.72
Starting 5 years earlier at the same inputs would mean $74,695.80 more.
Balance over time
ContributedGrowth
How this is calculated
FV = P(1+i)m + C × [ ((1+i)m − 1) ÷ i ]
- FV = projected future balance
- P = starting amount
- C = monthly contribution
- i = annual return ÷ 12 (decimal)
- m = years × 12
- Assumes monthly compounding with contributions made at the end of each month. If i = 0, the formula reduces to FV = P + C × m.
Worked example. Start with $10,000, add $100/month at a 6% annual return for 20 years. That's i = 0.06 ÷ 12 = 0.005 and m = 240 months. You'll have contributed $34,000 in total, but monthly compounding grows the balance to about $79,306 — more than double what you put in.
About the 7% assumption
A 7% annual return is a common long-run assumption for a diversified stock portfolio before inflation. Real returns vary wildly from year to year — up 20%, down 30% — and inflation eats into whatever nominal figure you see here. Fees, taxes, and behavior (selling in downturns) erode returns further. This is a projection based on the numbers you enter, not a promise about what your account will actually do.
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