For example in a trade you first analyze the market fundamentals and technicals then you make a move based on the existing market conditions. There will always be a small chance things change after you executed that trade, that is the risk part.
Calculated risk is something that differs from person to person. Because the amount of investment is different, the amount that people invest in different currencies is different for each one, and the people taking the level of risk are different. So what I am trying to tell you is that "calculated risk" is a vague term; it depends on many factors, so everything can't be spoon-fed. The amount of money that you can afford to lose is called calculated risk. Finding this risk before trading gives you a whole idea of your return amount so that you can analyze your money based on market trends and clearly understand when you want to stop.