Position Size Calculator
Size a position from account risk, stop distance and volatility.
Runs entirely in your browser · Nothing is sent or stored · No signup
Position size
147 units
$6,248 · 12.5% of account
Risk on this trade
Portfolio
Educational tool
Arithmetic on numbers you provide. Not financial advice, not a recommendation, and no assessment of whether any trade is appropriate for you. Trading involves substantial risk of loss.
Fixed-fractional vs volatility-scaled#
Fixed-fractional risks the same percentage of the account per trade, sized by stop distance. Simple and widely used.
Volatility-scaled additionally normalises by recent volatility, so a quiet instrument and a violent one contribute similar risk. This is usually the better default for a portfolio of dissimilar instruments.
The number to watch#
Not the position size — the total portfolio exposure. Sizing each position sensibly and holding twenty correlated ones at once is a concentrated bet wearing a diversified costume.
Related reading
Why Most Backtests Lie
Backtests fail in a consistent direction — optimistic. Here are the five structural reasons, with a detection method for each. Educational research only.