Calculate a compounded balance path from a starting balance, periodic rate and number of periods.
How this is calculated
Balance after each period = previous balance × (1 + rate per period ÷ 100) + deposit per period
With no deposits: ending balance = starting balance × (1 + rate ÷ 100) ^ number of periods
Total growth = ending balance − starting balance − total deposited
Total growth (%) = (total growth ÷ starting balance) × 100
Worked example
Starting balance $25,000.00, 2% per month, 24 months, no deposits.
Ending balance = 25,000 × 1.02^24 = $40,210.93.
Total growth = 40,210.93 − 25,000 = $15,210.93, or 60.8% of the starting balance.
Adding a $500.00 monthly deposit raises the ending balance further and adds $12,000.00 to total deposited, which is excluded from the growth figure.
Understanding compounding
Compounding applies each period's return to the balance produced by the previous period rather than to the original balance. The projection is a geometric series, so it grows non-linearly with the number of periods: the first year of a fixed rate adds far less than the fifth, because each period works on a larger base. The chart on this page draws that curve for the inputs you supply so the shape is visible rather than implied.
The model assumes a constant rate, and that assumption is the biggest gap between the curve and a real account. Trading returns vary from period to period and include losing periods, and variance itself reduces the compounded outcome. Two sequences with the same arithmetic average return produce different ending balances when one is choppier than the other, because a loss of a given percentage requires a larger percentage gain to reverse. The smooth line here is the best case for a given average, not the expected case.
The deposit field compounds contributions alongside returns. Each deposit is added after the period's return is applied, which matches how a monthly transfer into a funded account behaves. Total deposited is reported separately and excluded from the growth figure, because money you added is not money the strategy produced — conflating the two is one of the most common ways a track record ends up flattering itself.
Choose the period unit deliberately and keep the rate and the count in the same unit. A 2% monthly rate over 24 months and a 2% weekly rate over 24 weeks describe very different things, and per-trade rates are the easiest of all to mis-scale, since trade frequency is rarely constant. If you are converting from a per-trade figure, use your realistic historical trade count for the window rather than a target count.
Two caveats worth stating plainly. Position sizing usually scales with the balance, so the returns feeding a compounding path are not independent of the path itself, and a drawdown reduces both the base and the size of subsequent positions. And nothing here validates the rate: the output is an arithmetic consequence of the number you typed, not evidence that the number is attainable. Use it to understand the mechanics of compounding, and use your own trade records — not a chosen rate — to decide what is realistic.
Frequently asked questions
Is this a projection of expected returns?
No. It shows the arithmetic result of the constant rate you enter, which is not a forecast of market outcomes.
Why do real results differ from a smooth curve?
Because returns vary. Volatility drags the compounded result below what a constant average rate implies.
Can I model withdrawals?
This version compounds a balance without cash flows. Withdrawals reduce the base that compounds and are not included.
What period should I use?
Any consistent unit — daily, weekly or monthly — as long as the rate and period count refer to the same unit.