You can calculate the profit/loss for Forex currencies according to the following formulas. Please keep in mind that the calculation methods may differ depending on the trading instrument:
Forex currencies:
For a Buy order:
Profit/Loss = (Contract * ClosePrice)  (Contract * OpenPrice),
For a Sell order:
Profit/Loss = (Contract * OpenPrice)  (Contract * ClosePrice), where:
 Profit/Loss – the size of the profit/loss in the quote currency;
 Contract – contract size in the base currency;
 ClosePrice – closing price of the currency pair;
 OpenPrice – opening price of the currency pair.
For example:
Let's calculate the profit/loss for a Sell order on EURGBP.
LotSize = 0.19.
Trading instrument (currency pair) – EURGBP.
OpenPrice EURGBP = 0.6983.
ClosePrice EURGBP = 0.6883 (100 points = 0.6983  0.6883 = 0.0100).
Now, we need to calculate the deal size:
Deal size = Contract size * Lot size.
Contract size = 100000 EUR.
Deal size= 0.19 * 100000 = 19 000 EUR.
GBPUSD rate = 2.0256 (necessary to convert profit/loss size into US dollars).
Calculation:
 Profit/Loss = (19 000 * 0.6983)  (19 000 * 0.6883) = 13267.7 – 13077.7 = 190 GBP.

Convert one point value into the deposit currency (US dollar). If the US dollar is the first currency in the pair that we are calculating for (like USDCHF), we should divide one point value by the BID PRICE; if the US dollar is the second currency in the pair (like EURUSD)  multiply by the ASK PRICE:
Profit/Loss = 190 GBP * 2.0256 = 384.86 USD.
As for Metals, Energies, Indices, and Stocks, the profit/loss can be calculated according to the following formulas:
For a Buy order:
Profit/Loss = (ClosePrice  OpenPrice) * ContractSize * LotSize
For a Sell order:
Profit/Loss = (OpenPrice  ClosePrice) * ContractSize * LotSize, where:
 ContractSize – contract size in the trading instrument;
 ClosePrice – closing price of the trading instrument;
 OpenPrice – opening price of the trading instrument;
 LotSize– the measure of the order.
For example:
Let's calculate the profit/loss for a Sell order on XAUUSD.
LotSize = 0.02.
Trading instrument (currency pair) – XAUUSD.
OpenPrice XAUUSD = 1911.15.
ClosePrice XAUUSD = 1716.25 (100 points = 1911.15  1716.25 = 194.9).
Contract size = 100 tr oz of gold.
Calculation:
(1911.15  1716.25) * 100 * 0.02 = 389.9 USD.