Both sides sit on one screen with no tabs and no toggle: compound growth on one side, the cost of a drawdown and the recovery it demands on the other. Showing growth apart from the cost of a drawdown is what makes compounding calculators misleading, so here they are never separated.
What compounding is and why it looks dramatic on paper
Compounding is the reinvestment of gains, so the base each period is computed on is larger than the one before it. The result is that the absolute profit grows even when the percentage stays exactly constant. The formula is the standard future value equation: the starting balance multiplied by one plus the rate, raised to the number of periods. That is mathematically beyond dispute, but it rests on a single assumption that does not hold in trading, which is the subject of the next section.
The assumption every compounding calculator hides
The assumption every compounding calculator hides is that the same percentage repeats every period without exception. A single losing period breaks the chain completely, and it does not merely deduct itself: it lowers the base every later period is built on. More subtly, the order itself changes the outcome, because a positive return followed by a negative one does not give what a negative followed by a positive gives when the percentages are measured against a moving balance. That is why the notice sits above the ending balance and cannot be dismissed.
Worked example: twelve periods at 5%
Take a starting balance of 10,000 dollars and twelve periods at 5% each. The first period ends at 10,500, the second at 11,025 and the third at 11,576.25. Note that the absolute profit rose from 500 to 525 to 551.25 even though the percentage never changed. After twelve periods the balance reaches 17,958.56 dollars, a total profit of 7,958.56 and total growth of 79.59%. The full period-by-period table appears above.
The other side: losses compound too
The other side uses the same formula with a negative rate and needs not one line of extra logic. But it behaves differently in one important direction: each loss is computed on a smaller balance than the one before, so the absolute loss shrinks. The consequence is that the total drawdown is less than the simple sum of the percentages — ten losses of 5% do not give 50% — while at the same time being far larger than most traders expect when they do the arithmetic in their heads.
Worked example: twenty-five losses at 2%
Take twenty-five consecutive losses at just 2% each, a figure that looks very conservative. The balance falls from 10,000 to 6,034.65 dollars. The resulting drawdown is 39.65%, and the gain needed to recover it is 65.71%. That is the number worth pausing on: a risk percentage its owner would be called disciplined for using produced a drawdown needing more than two thirds of what remains simply to get back to zero.
Why recovery is asymmetric to the loss
Recovery is asymmetric to the loss for one simple reason: the two percentages are measured against two different bases. The loss is measured against the balance before it, and the required gain against the balance after it, which is smaller. A 20% loss needs a 25% gain, 30% needs 42.86% and 50% needs 100%. Past half the capital the curve explodes: 70% needs 233.33% and 90% needs 900%. The reference table above is fixed, does not depend on your inputs, and is shown at all times for exactly this reason.
Worked example: the canonical 50% case
The canonical case the sources publish by name is a 50% loss. A 10,000 dollar balance falls to 5,000, the drawdown is 50%, and the gain required to recover is exactly 100%. Bogleheads states it in words: with a loss of 50%, one needs a gain of 100% to recover. The peer-reviewed Newall paper states it the same way and adds real figures: the 2007 to 2009 fall of 50.8% required a 103.4% return to break even.
What this means for how much you risk
The practical effect on position risk shows up in figures rather than advice. At 2% risk you need roughly twenty-five consecutive losses to reach a 40% drawdown. At 5%, ten losses reach 40.13%. At 10%, about five losses pass 40%. The higher the risk percentage, the shorter the streak needed to create a drawdown that is hard to make back. That is an arithmetic relation you can verify by changing the two fields above, not an opinion about what you should risk.
The limits of this tool
Three explicit limits. The first is that this tool forecasts nothing: it is a calculation on an assumption you supply, and the assumption is the weakest link. The second is that it does not measure the likelihood of the losing streak; it tells you the effect of twenty-five consecutive losses and not the odds of them happening, which is another tool question. The third is that it assumes no distribution of outcomes and no ordering, so it computes one specific case rather than a range of them.
Frequently asked questions
Why does a 50% loss need a 100% gain to break even?
Because the two percentages are measured against different numbers. Losing 50% of 10,000 leaves 5,000, and getting from 5,000 back to 10,000 means adding 5,000 to a balance of 5,000 — that is 100% of it. The base is 10,000 in the first case and 5,000 in the second. Bogleheads puts it as ‘the same dollar amount being expressed as a percentage of two different starting amounts’.
Why does this calculator show compounding and drawdown together rather than separately?
Because showing growth without the cost of a drawdown gives half the picture. A tool that displays a large ending balance after twelve winning periods, with no indication of what a losing streak does, describes only one side. Both sides run on the same arithmetic: a percentage compounding on a moving balance, once upward and once downward.
Can I actually achieve the fixed rate I entered?
No. The calculator assumes an identical rate every period because the arithmetic requires it, but real trading performance includes losing periods, flat periods and periods with widely different results. The figure shown is an arithmetic exercise on an assumption — not a forecast, not a target and not a promise. That is exactly why the fixed warning sits above the result and cannot be dismissed.
What is the difference between the loss streak field and the standalone drawdown field?
The loss streak field builds a drawdown out of consecutive trades at a known loss per trade, answering: what happens if I lose five trades at 2% each. The standalone field accepts a finished percentage, answering: what does recovering a 20% drawdown take, whatever caused it. The first constructs the drawdown; the second receives it.
Why does a small risk percentage like 2% still produce a large drawdown?
Because losses compound the same way gains do. Twenty-five consecutive 2% losses do not add up to 50% by simple addition — they come to roughly 39.65%, because each loss is measured against a smaller balance than the one before. The figure is lower than plain addition, yet far higher than most traders expect, and recovering it takes a gain of about 65.71%.
Does this calculator tell me what risk percentage I should use?
No. It returns arithmetic results for numbers you supply; it recommends no risk percentage, no trade count and no strategy. What it does is put the cost of a drawdown in figures and leave you to read that cost against your own capital and loss tolerance. The decision remains yours.