See how a starting balance and regular monthly contributions grow over time, and how much of the final total comes from growth rather than deposits.
Ending balance
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Total contributed
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Total growth
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Growth share of the total
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Balance by year
Year by year table
Year
Contributed
Growth
Balance
How it works
Compounding means each year’s growth earns its own growth the following year. Early on the deposits do most of the work; given enough time, growth overtakes them.
The calculator adds your contribution at the end of each month and applies the yearly return at the compounding frequency you pick. More frequent compounding adds a little extra, but time and the rate matter far more.
The formula
Monthly rate = (1 + Rate ÷ n)^(n ÷ 12) − 1, where n is compounding periods per year
Starting with $10,000 and adding $500 a month at 8% a year, compounded monthly, gives about $343,800 after 20 years. You put in $130,000; the other $213,800 or so is growth.
Compound Interest questions
What return should I use?
Use a conservative figure. Broad US stock indexes have returned around 10% a year over very long periods before inflation, with large swings along the way. A lower number gives a safer plan.
Does this account for inflation or taxes?
No. To see the result in today’s dollars, lower the return by your expected inflation rate, for example 8% minus 3% gives 5%.
How much does compounding frequency matter?
Less than most people expect. Going from yearly to daily compounding at 8% adds well under one percentage point a year; the return and the number of years dominate.
For informational and educational purposes only. Not investment advice, and not a recommendation to buy or sell any security. Results are estimates from the numbers you enter.