How many units to trade so a loss costs exactly what you decided.
Educational tool only — not financial advice. Verify figures with your broker.
The Position Size Calculator is a risk-and-sizing tool that answers a single question: how many units (or lots) should I trade so that if my stop is hit, the loss equals exactly the amount I decided to risk? It converts a chosen dollar or percentage risk and a stop distance into a concrete position size. It sizes the trade; it does not judge the trade.
Position size = risk amount divided by (stop distance in pips x pip value per unit). The risk amount itself is account equity x risk percent. In words: decide how many dollars you can lose, divide by how many dollars you lose per unit if the stop is hit, and that quotient is how many units keep the loss at your chosen figure.
Many traders cap risk at a small fixed fraction of equity (commonly cited around 1-2%), but the right number is a personal risk decision, not a formula output. The calculator sizes whatever percentage you enter; it does not recommend one.
No. It assumes your stop fills exactly at the stop price. Real fills can be worse during fast moves or gaps, so an actual loss can exceed the figure shown.
Because the loss per unit grows with stop distance. To keep the total risk fixed, the number of units must shrink as the stop widens.
Keep in mind: This number tells you the size that caps a clean stop-out at your chosen risk. It does not tell you whether the trade will win, and it cannot guarantee the actual loss, since slippage, gaps, and requotes can push the real fill past your stop.