Choose how much of the account you accept to lose, set the stop in pips, and get the lot size.
Risk warning. Leveraged products such as forex and CFDs lose money quickly and most retail accounts lose. These calculators do arithmetic on the numbers you type. They are education, not advice, and not a recommendation to trade anything.
Fix the amount you accept to lose first, then let the stop distance decide the size. The risk amount is balance × risk %. The lot size is that amount divided by the stop in pips times the value of one pip per lot.
The result is rounded down to 0.01 lots so the real loss never exceeds the amount you chose.
Spread, commission and slippage add to the loss. Add the spread to the stop distance and keep the risk small.
There is no right number for everyone. Many educators discuss 1% or less. This tool only computes the size for the figure you choose.
So the loss at the stop is never larger than the risk you set.
No. For shares, indices and other instruments use the position size calculator.