The formula, worked once
Fixed-fractional sizing runs in two steps. First the dollar risk: a $10,000 account risking 1% puts $100 on the line. Then the size that makes your stop cost exactly that: with a 25-pip stop and a $10 pip value per standard lot, each lot loses $250 at the stop, so $100 ÷ $250 = 0.40 lots. Change any input and the output shifts proportionally — half the stop distance doubles the size at the same dollar risk, which is why tight stops tempt oversizing and why the dollar risk, not the lot number, is the decision that matters.
Pip value is where calculators quietly lie
Most position-size tools hard-code $10 per pip per lot. That's roughly right for USD-quoted majors on a USD account and wrong nearly everywhere else: JPY pairs move in different units, crosses depend on conversion rates that change with price, gold contracts vary by broker, and a EUR-denominated account shifts every value again. This page makes pip value an editable input instead of a hidden assumption — read the real number from your platform's symbol specification (in MT5: right-click the symbol → Specification) and the arithmetic stays honest.
What this calculator refuses to decide
It will not pick your risk percent. One percent per trade is a common default because it survives long losing streaks — ten straight losses cost about 9.6% of the account — but the survivable number depends on your win rate, payoff, and how correlated your positions run. That's a ruin question, not a sizing question, and the risk-of-ruin calculator answers it with your own numbers. Nothing you type here is uploaded; the math runs in your browser.