Position size calculator
How the position size calculator works
Most costly trading mistakes are sizing mistakes. This position size calculator reverses the usual order of thinking: first decide what share of your account you are prepared to lose if the trade fails, then measure the distance to your stop-loss, and only then work out how large the position can be.
Pip value per lot is $10 for pairs quoted in US dollars; for other pairs the calculator converts using the price or rate you enter.
A worked example
An illustrative account holds $8,000 and the trader risks 1.5% per idea. That is 8,000 × 0.015 = $120. The trade is on GBP/USD with a stop 30 pips from the entry. One lot of GBP/USD is worth $10 per pip, so one lot would lose 30 × $10 = $300 at the stop. To lose only $120, the position must be 120 ÷ 300 = 0.4 lots.
Check it the other way: 0.4 lots is $4 per pip, and 30 pips × $4 = $120. The sums agree.
Reading and using the result
The answer is the largest position consistent with your rule. Brokers trade in fixed steps, often 0.01 lots, so round down if the result falls between steps. Remember that the stop-loss is not a guarantee: in a fast market or over a weekend gap the fill can be worse than the stop price, so the real loss can exceed the planned one.
Risk per trade is a personal choice, and we do not suggest a figure. What the arithmetic makes plain is that small percentages protect an account from a run of losses, which every approach suffers sooner or later. Ten consecutive losses at 1.5% each leave most of the account intact; ten at 15% do not.
Once you have a size, the margin calculator shows how much of your balance it ties up, and the pip calculator confirms what each pip is worth.