See how a starting amount and monthly savings grow over the years, in any currency, with the answer also shown in today's money. Or turn it around and find how much to save a month to reach a goal.
No sign-up, nothing saved, works in any currency.
The lump sum you invest today. Leave it at 0 if you are starting from nothing.
What you add every month, on top of the starting amount.
How many years you keep adding money and let it grow.
years
The average growth you expect each year, before inflation. Pick an average below or type your own. It is a guess, not a promise.
Optional. Adds a low and a high outcome: with a 10.7% return and 2 here, they use 8.7% and 12.7%. Leave 0 for one line.
% points
How often growth is added to your balance. Yearly matches how market averages are quoted; savings accounts often use monthly or daily.
Optional. The yearly price rise you expect, for example 3. The result is then also shown in today's money.
% a year
Enter a starting amount or a monthly contribution, and the number of years.Your projection appears here as you type.
StockFly tracks what your real investments actually did, in any currency.
Questions, answered
What is compound interest?
Growth on top of growth. Each period, the return is added to the balance, and the next period's return is calculated on the bigger balance. Over decades this is why the growth line bends upward instead of rising in a straight line.
How is this different from a simple interest calculator?
Simple interest pays the same amount every period, on the original sum only. Compound interest pays on the original sum plus everything it has already earned. The gap is small in year one and enormous in year thirty.
Which return should I use?
Nobody knows future returns, so use a long-run average and a range. The presets give sourced averages: the S&P 500 returned about 10.7% a year from 1957 to 2026 with dividends reinvested, about 6.8% after inflation. A broad global stock index sits a little lower, bonds lower still. The give-or-take field shows what happens if reality lands a couple of points either side.
Why is the result also shown in today's money?
A million in thirty years buys far less than a million today. Taking the inflation rate off the balance for every year turns it into an amount you can compare with prices you know. At 3% inflation, money loses about 59% of its buying power over thirty years.
How do monthly contributions and the compounding setting work together?
Contributions are pooled for each compounding period and added at the end of it. With yearly compounding, a year's twelve deposits earn nothing until the year ends. With monthly compounding each deposit starts earning the next month. With daily compounding the monthly amount is spread evenly over 365 days. The step-by-step guide linked under the calculator shows the formula.
Is this a forecast?
No. It is arithmetic on the assumptions you enter. Real markets do not return the same percentage every year, and a long-run average says nothing about the next five years. StockFly shows the projection so you can compare choices, and tracks what your real investments actually did so you can see the difference.