Position Size Calculator
Decide what you are willing to lose, then let the stop decide the size. Enter a balance, a risk figure, an entry and a stop, and the position that risks exactly that much comes out.
Position size
units at the entry price
You risk
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Stop distance
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Position value
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Leverage
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This is a calculator, not advice. It works only on the numbers you type in — it has no market data and no opinion on what you are trading. Nothing here is a recommendation to open, close or size a position, and technical analysis describes probabilities rather than outcomes. Fees, spread and slippage sit on top of the risk figure shown.
The part a calculator cannot do
This page does the arithmetic once you have an entry and a stop. Choosing where the stop goes is a question about the chart — Chart AI reads a photo of one and talks through the trend, the levels, the volatility and the volume on it, and keeps every analysis in a history you can compare against later.
The whole formula
Position sizing has exactly one equation, and it is short enough to do in your head: size = what you are willing to lose ÷ distance to your stop. Risking 100 on a stop that sits 5 away from the entry means 20 units. The same 100 on a stop 0.5 away means 200 units. Nothing else in the calculation matters — not how confident you are, not how good the setup looks, not what the instrument is.
Everything else on the panel is derived from that one number. Multiply the size by the entry and you get the position value; divide the position value by the account and you get the leverage the trade implies. Those two are worth glancing at, because a size that looks reasonable can quietly turn into a position several times the size of the account when the stop is tight.
Why the stop has to come first
The order matters more than the arithmetic. A stop is a statement about the chart: this is the price at which the reason for the trade no longer holds. Below a level that held three times, past the swing that defined the trend, outside the range the instrument moves in on an ordinary day. Once that price is chosen, the size is not a decision at all — it is a division.
Doing it the other way round is what turns this calculation into theatre. Deciding the size first and then finding a stop that "fits" it produces a stop sitting inside the instrument's normal noise, which gets hit for reasons that have nothing to do with whether the idea was right. The account still loses the same 1%, but it loses it to randomness rather than to being wrong.
Fixed fractional sizing, and what it does over time
Risking a set percentage of the current balance — rather than a set number of dollars — is what makes drawdowns shrink as they deepen. Each loss is taken from a smaller balance, so the losses get smaller in absolute terms, which is why an account risking a fixed fraction cannot arithmetically reach zero from losses alone. The same property works against you on the way back up: recovering takes longer than the drop, because a 20% fall needs a 25% rise to undo.
What this page does not know
It has no market data. It does not know whether your stop is in a sensible place, whether the instrument gaps over weekends, or how wide the spread gets in the hour you plan to trade. It assumes you are filled at the entry price and stopped at the stop price, and both of those are approximations — a gap through a stop level is filled wherever the market reopens, which is the one case where the loss is not capped at the figure shown here.
Questions
What percentage should I risk per trade?
That is a decision about your own money and this page cannot make it for you. What it can tell you is what each choice costs arithmetically: a run of ten losing trades takes about 9.6% off an account risking 1% each time, 22% at 2.5%, and 40% at 5%. Losing streaks of that length are ordinary at any win rate below about 60%, so the figure you pick is really a statement about the drawdown you can sit through without changing your mind.
Does this work for stocks, forex and crypto?
Yes. The formula does not care what is being traded, as long as the price and the account balance are quoted in the same currency — then the answer comes out in whatever the price is per unit: shares, coins, or contracts. Forex is the one that needs a second step, because the result is in units of the base currency and you have to divide by the contract size (100,000 for a standard lot, 10,000 for a mini) to get the lot size.
Why is the position bigger than my whole account?
Because a tight stop needs a large position to put the same amount of money at risk. If your stop is 0.5% away and you are risking 1% of the account, the position has to be roughly twice the account to lose exactly that 1%. That is what the leverage figure on the panel is telling you, and it is only possible on a margin or derivatives account. On a cash account you cap the size at what you can actually buy and accept that the trade risks less than your budget.
Should the stop go where the size works out nicely?
It is the wrong way round, and it is the most common way this calculation gets misused. The stop belongs at the price that says the idea was wrong, which is a question about the chart. The size is then whatever falls out of that. Moving the stop closer to afford a bigger position does not reduce the risk — it just makes it more likely the trade is closed by noise before anything is settled.
Does it account for fees and slippage?
No, and both make the real loss slightly bigger than the figure shown. Commission, the spread you cross on the way in and out, and the gap between your stop price and your actual fill all sit on top. On liquid instruments with a wide stop the difference is small; on a thin market, or a stop a few ticks away, it is not, and gaps through a stop price are the case where the loss is not capped at all.
