In Forex trading, a pip (percentage in point) is the smallest unit of measurement for the change in the value of a currency pair. The pip value is determined by the currency pair being traded, the size of the trade, and the exchange rate of the currency pair.

Most currency pairs are quoted to four decimal places, with the exception of the Japanese yen pairs which are quoted to two decimal places. In a currency pair that is quoted to four decimal places, a pip represents the fourth decimal place. For example, if the EUR/USD currency pair is trading at 1.2345, a move to 1.2346 represents a one-pip movement.

To calculate the pip value, you need to know the pip size of the currency pair you are trading and the size of your trade in lots. A lot is a standardized trading size in Forex and is typically 100,000 units of the base currency. Some brokers offer smaller lot sizes, such as a mini lot (10,000 units) or a micro lot (1,000 units).

The formula for calculating the pip value is as follows:

Pip Value = (Pip size in decimal places / Exchange rate) * Trade size in lots

For example, if you are trading the EUR/USD currency pair at an exchange rate of 1.2345 and your trade size is one standard lot (100,000 units), the pip value would be:

Pip Value = (0.0001 / 1.2345) * 100,000 = $8.10

This means that for every one-pip movement in the EUR/USD currency pair, you will make or lose $8.10, depending on whether the movement is in your favor or against you.

To calculate the profit or loss on a trade, you need to know the number of pips gained or lost and the pip value. For example, if you bought the EUR/USD currency pair at 1.2345 and sold it at 1.2365, you would have gained 20 pips. Using the same trade size of one standard lot and pip value of $8.10, your profit would be:

Profit = Number of pips * Pip value * Trade size in lots

Profit = 20 * $8.10 * 1 = $162

In this example, you would have made a profit of $162 on the trade. Conversely, if you had sold the EUR/USD currency pair at 1.2345 and bought it back at 1.2325, you would have lost 20 pips. Using the same trade size and pip value, your loss would be:

Loss = Number of pips * Pip value * Trade size in lots

Loss = 20 * $8.10 * 1 = $162

In this example, you would have lost $162 on the trade.