In plain English
What Position sizing means
A trader can be correct about direction yet take a position that is too large for the account. Position sizing combines the distance to a stop-loss order, the instrument’s value per price movement, and the amount the trader is prepared to lose if that stop is reached. In forex, lot size changes the monetary value of each pip, so the same stop distance can create very different cash risks.
Why it matters
Position sizing makes risk measurable across trades with different prices, volatility, and stop distances. It also helps distinguish margin required to open a trade from the amount that could be lost. Leverage can permit a large position with a small deposit, but it does not reduce the loss caused by an adverse price move.
Example
Assume a $10,000 account has a $100 maximum loss for one trade. A proposed EUR/USD trade has a 50-pip stop, and each pip is worth $2 at the selected size. Estimated stop loss is 50 × $2 = $100, before spread, slippage, financing, or commissions. The $2-per-pip size fits that limit; a $5-per-pip size would risk about $250.
Quick answers
Common questions
Is position sizing the same as leverage?+
No. Leverage describes how much market exposure can be controlled relative to funds committed. Position sizing is the chosen exposure itself, based on a risk method or trading plan. A trader can use available leverage without using all of it.
What is a basic position-sizing formula?+
A simplified formula is maximum cash risk divided by the loss per unit if the stop is reached. For forex, that loss commonly depends on stop distance in pips multiplied by the pip value at the proposed lot size.
Sources