Profit/Loss Calculation
Calculation of formulas

break-even formula
Profit/Loss = [ ( ( Sell price - Buy price ) x contract unit x number of lots ] - Handling Fee ± Interest = [ ( Spread x pip value ) x number of lots ] - Handling Fee ± Interest
Spread formula
( Sell price - Bid price ) / Tick size
Point value formula
Contract unit ( Lot size ) x Number of basis points ( Tick size )
Interest formula
(Straight) | Interest Rate (Rate) x Open Price (Price) x Contract Size (Size) x Lot (Lot) x Days (Days) / 360
(Cross) | Interest Rate x Price x Contract Size x Lot x Days / 360 / Same day closing price of (latter currency)
give an example
The customer bought 2 lots of GBPUSD, when the purchase price of $ 1.75050, put in a margin of $ 1750.5, the closing price of the day for the 1.75100, and the next day to $ 1.75400 to close the position of 2 lots of GBPUSD, his foreign exchange trading profit for:
1.75400 ( Ask ) - 1.75050 ( Bid ) = 0.00350 = 350 points ( Profit )
Transform the above profit or loss into dollars as follows:
350 (pips) x 200,000 (contract units) x 0.00001 (basis points) = $700 (profit)
Handling fee: 50 ( USD / lot ) x 2 = $100 ( Handling fee )
Interest: Buy: -3% Sell: 0%
3% x 1.75050 x 100,000 x 2 x 1 / 360 / 1.75030 = 16.6686 ( interest )
Profit and Loss : 700 - 100 - 16.6686 = 583.3314 ( Net Profit )