Trading Compound Interest Calculator
Project how an account could grow from a starting balance, a monthly return and regular deposits. Real returns vary, and losses compound too.
How to use the compounding calculator
Enter a starting balance, an assumed monthly return, the number of months and an optional monthly deposit. The calculator reinvests each month's return and shows the final balance and the total gain over what you put in.
The compounding formula
Each month: new balance = balance × (1 + monthly return) + deposit.
Example: $5,000 growing at 2% a month for 12 months with no deposits ends at about $6,341, a gain of $1,341. The same 2% for 36 months ends at about $10,199.
Use realistic assumptions
Trading returns are uneven. Most months are not average months, and losing months compound as well. A projection is a planning tool, not a forecast. Test assumptions against your own results from a trading journal and a proper backtest.
Before chasing growth, protect the downside: see the drawdown calculator for how hard losses are to recover.
Frequently asked questions
How does compounding work in trading?
Profits are added to the account, so the next period's return is earned on a larger balance. Losses shrink the base in the same way.
What is a realistic monthly return?
There is no reliable figure. Returns vary widely and many traders lose money. Use conservative assumptions and your own track record.
Do deposits change the result much?
Yes. Over long periods, regular deposits often add more to the final balance than the returns themselves.
Is this a forecast?
No. It shows the maths of a fixed return. Real results will differ.