TRADE ANALYSIS
Compound Growth Calculator
Set a starting balance, a return per week or month, and a horizon — with optional contributions — and watch the curve. Compounding is the quiet argument for consistency over home runs.
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THE MATH
Growth on top of growth
Each period's return is earned on everything the account already holds — the original stake, every previous gain, and every deposit made along the way.
balance(n) = balance(n−1) × (1 + r) + contributionWithout contributions this collapses to the familiar start × (1 + r)ⁿ. The consequence is geometric, not linear: at 1.5% per month an account doesn’t grow 18% a year, it grows 19.6% — and after four years it hasn’t doubled once, it’s at 2.04×. The curve is deceptively flat at the start and steep at the end, which is exactly why traders underrate small consistent returns and overrate big sporadic ones.
Contributions bend the early curve upward where compounding is weakest. A modest deposit each month does most of its work in the first years, then hands over to the compounding itself.
COMPOUND GROWTH CALCULATOR
LiveFINAL BALANCE
$28,910.39
after 36 months
TOTAL GAIN
+$9,910.39
growth beyond deposits
MILESTONES
Assumes the same return every period — real trading returns are lumpy, so treat this as a trajectory, not a forecast.
WORKED EXAMPLE
$10,000 at 1.5% a month, three years
A trader compounds $10,000 at 1.5% per month for 36 months, adding $250 at the end of each month.
The stake alone grows to 10,000 × 1.015³⁶ ≈ $17,091. The $9,000 of contributions, each compounding from the month it arrives, adds roughly $11,818 more — a final balance near $28,900. Total gain beyond deposits: about $9,900, on an account that never had a spectacular month. Halve the horizon and the picture changes sharply: at 18 months the balance is only ≈ $18,200. The second half of the horizon produced nearly two-thirds of the growth — that back-loaded shape is the signature of compounding, and the reason quitting early is so expensive.
Now the darker symmetry: compounding works identically in reverse. One −20% month undoes about fifteen months of +1.5% grinding, because losses subtract from the base that every future return multiplies. Consistency beats home runs not because home runs aren’t nice, but because the blow-up months that come with swinging for them are geometrically expensive.
HONESTY CLAUSE
No account grows in a straight line
A fixed return per period is an idealization — useful for setting expectations, useless as a forecast.
Real trading returns are lumpy: flat weeks, drawdowns, the occasional outsized month. The projection here shows what a given average implies over time, not what any particular year will look like. Two things make the idealization more honest: use a per-period return you have actually sustained over a meaningful sample (your journal’s monthly expectancy, not your best month), and stress-test the same edge with the Monte Carlo simulator to see the dispersion the smooth curve hides.
FAQ
Is a fixed return per period realistic?＋
No — and the calculator says so on its face. Real returns vary period to period, and the sequence matters for drawdowns even when the average holds. Use the tool to understand what an average implies over a horizon, then use a Monte Carlo simulation to see the realistic spread around that path.
What monthly return should I plug in?＋
The one your own records support. World-class long-run track records compound near 1.5–2.5% per month; consistently profitable retail traders are often below that. If you're tempted to type 10% per month, note that would turn $10,000 into roughly $3M in five years — the market pays that to almost no one, sustainably to no one.
How are contributions handled?＋
Each contribution is added at the end of its period, after that period's return — so a deposit starts compounding from the following period. Total gain is reported net of deposits: final balance minus starting balance minus everything you contributed.
Weeks or months — which should I use?＋
Match the rhythm you actually measure yourself in. Weekly compounding at small rates and monthly compounding at the equivalent rate produce nearly identical outcomes; what matters is that the return you enter was measured over the same unit you select. The horizon is capped at 520 periods — ten years of weeks.
Why does the curve look flat at the beginning?＋
Because early gains are earned on a small base. Compounding is back-loaded: in a typical multi-year projection, well over half the total growth arrives in the final third of the horizon. That's the mathematical case for staying consistent long enough to reach the steep part.
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Real equity curve from imported trades · weekly and monthly breakdowns