Position size calculator
This position size calculator answers the question that matters most before a trade: how big should it be? Enter your balance, the percentage you are prepared to risk, the pair and the distance to your stop-loss in pips. The result is the lot size at which hitting the stop would cost that amount, before spreads and fees.
The formula
Units = cash risk ÷ (pips to the stop × dollar value of one pip on one unit)
Lots = units ÷ lot size (100,000, or 100 oz for gold)
That per-unit pip value uses the same maths as the pip calculator. For USD-quoted pairs one pip on one unit is worth $0.0001, which is $10 per standard lot.
Worked example (illustrative figures)
Your account holds $8,000 and you decide to risk 1.5% on a EUR/USD trade with a 30-pip stop.
- Amount at risk: $8,000 × 1.5% = $120.
- Loss per standard lot if the stop is hit: 30 pips × $10 = $300.
- Position size: $120 ÷ $300 = 0.4 lots, or 40,000 units.
If you widened the stop to 60 pips, the same $120 risk would allow only 0.2 lots. The stop distance comes first; the size follows from it.
Reading the position size calculator result
The figure is a maximum, not a target. Round down to the nearest size your platform allows. Remember that a stop-loss is not guaranteed: in fast markets or over a weekend gap it may be filled at a worse price, so the real loss can exceed the planned one. Many traders keep risk per trade to a small percentage precisely because several losses in a row are normal.
Choosing a risk percentage
There is no correct figure, but the arithmetic of losing streaks is worth knowing. Using illustrative numbers, ten losses in a row at 1% each leave about 90.4% of the starting balance; at 5% each they leave about 59.9%. Recovering from the second position requires a gain of roughly two-thirds just to get back to the start. Smaller risk per trade keeps a bad run survivable.
Also check the margin the trade needs with the margin calculator; a correctly sized trade can still be blocked if your free margin is too low.