Growth over time
Year by year
The formula
How it works
Compounding means you earn returns on your returns. Contributions add up linearly, but the growth curve bends upward over time as interest starts earning interest of its own — which is why starting early matters so much.
FAQ
Is this adjusted for inflation?
No — these are nominal figures. Real purchasing power will be lower depending on future inflation.
How often does it compound?
Monthly, with contributions added at the end of each month.
How is compound interest different from simple interest?
Simple interest is earned only on the original principal, so it grows in a straight line. Compound interest is earned on the principal plus all previously added interest, which is why the balance curve bends upward and accelerates over time.
Does increasing the monthly contribution matter as much as the rate?
Both matter, but their impact differs by timeframe. Over shorter periods, contributions tend to dominate the balance, while over longer periods small differences in the assumed annual return compound into much larger gaps in the final figure.
What does the rule of 72 tell me?
Dividing 72 by your annual return gives a rough estimate of how many years it takes your money to double, ignoring contributions. At 7%, for example, that is about 10 years — a quick sanity check alongside the full projection here.
Are taxes on the interest earned included?
No, the future value shown is before any tax on interest, dividends or gains. Depending on the account type and jurisdiction, tax could be due each year or only when funds are withdrawn, which would lower the real growth compared to this projection.
What happens if I stop making monthly contributions partway through?
This calculator assumes a constant monthly contribution for the entire period, so pausing or changing contributions isn’t reflected. To approximate a change, split the timeline into segments and run each one separately, using the prior segment’s future value as the next starting amount.
Why compound interest grows so fast
Compounding means you earn returns not only on your original deposit but also on the returns already added. Over a few years the effect is modest, but across decades the growth curve bends sharply upward as interest starts earning interest of its own. This is why starting early usually matters more than investing larger amounts later on. The balance after months is , where is the monthly rate.
Contributions versus growth
Two forces build the final balance: the money you put in — your starting amount plus every monthly contribution — and the interest earned on it. Early on, contributions dominate. Later, growth takes over and can end up larger than everything you contributed combined. The split shown here makes that crossover visible.
A note on the assumptions
These are nominal figures compounded monthly, with contributions added at the end of each month. Real returns vary from year to year and inflation erodes future purchasing power, so treat the result as a projection rather than a guarantee.