Trading Account Compounding Calculator
Enter a starting balance, a per-period return and any regular withdrawal, and this projects the account forward — showing how quickly withdrawals overtake growth when the rate assumption is optimistic.
What this is useful for
Comparing scenarios. Does withdrawing $500 a month materially change the two-year outcome? At what point does a fixed withdrawal exhaust the account? Is it better to compound for a year first and then start drawing? Those are real questions and this answers them cleanly.
What it is not useful for
Predicting anything. The model assumes an identical return every single period, and no trading account has ever produced that. Real accounts have losing months, and losing months interact with withdrawals in a way that a smooth model cannot show: the withdrawal comes out of a smaller balance, so the recovery has less capital to work with, and the effect compounds.
Set the return to 3% a month and the calculator produces roughly a 100% gain over two years. A real account averaging 3% a month with normal volatility ends up meaningfully below that, because losses cost more than equivalent gains return.
The monthly return trap
3% a month sounds modest. It compounds to 42.6% a year, and 10% a month compounds to 213% a year. Anyone projecting a trading account at 10% monthly is projecting a return that would make them one of the best traders alive, sustained, with no losing months. The arithmetic is what makes these figures so popular in trading marketing — the compounding does the exaggerating for you.
A useful discipline: put your own measured monthly return in the field, taken from a complete record. If you do not have a complete record, the honest input is that you do not know the number yet.
Withdrawals change the risk profile
A fixed withdrawal is a fixed cost against a variable return, which converts a volatile-but-growing account into one that can hit zero. Set the return to 1% and the withdrawal to $500 in the default and watch the account get exhausted. Traders funding living expenses from an account frequently discover this the expensive way: the strategy did not fail, the withdrawal schedule did.
Compounding cuts both ways
Kelly's 1956 result is the reason this curve is so sensitive to the risk input: growth is maximised at a finite fraction of capital, and betting above it lowers long-run growth even when the edge is unchanged.[1]
The number is the easy part
Everything above is arithmetic, and anyone opening this page gets the same answer. What no calculator can settle is whether you took the trade on these terms, or are describing — afterwards — the version of it that worked out.
That is what a trade recorder is for: the trade committed before it resolves, timestamped and sealed on the spot, on a Merkle-anchored log a stranger can check without kappi's cooperation. The plan you typed here stops being a plan you remember having. $15/month, no free tier.
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Frequently asked questions
How do I project trading account growth?
Multiply the balance by (1 + return) each period, subtracting any withdrawal after the return is applied. This calculator iterates that period by period.
Is a 10% monthly return realistic?
It compounds to 213% a year with no losing months. Sustained, that would place a trader among the best in the world — which is why the figure appears so often in marketing and so rarely in audited records.
Why do withdrawals hurt more than they appear to?
A fixed withdrawal against a variable return takes capital out of a smaller base after losing periods, so the recovery has less to work with. The effect compounds.
Why does a smooth return overstate real growth?
Volatility drag. A sequence averaging 3% a month with real ups and downs ends below a constant 3%, because a loss needs a larger percentage gain to undo.