The method of calculating profit on Forex depends on the currency pair quote.
If the base currency of the pair is USD, it is called the direct quote (e.g.USD/JPY, USD/CAD, USD/CHF).
If USD is the counter currency, this is a currency pair with the indirect quote (e.g. EUR/USD, GBP/USD, AUD/USD).
If the currency pair does not include USD, you deal with the cross-rate (e.g. GBP/AUD, GPB/JPY).
Calculation and Formula
You can calculate profit for the direct currency pairs by the formula:
(closing price – open price) / closing price × contract volume × lot size
Here is the formula for currencies with the indirect quotation:
(open price – closing price) × contract volume × lot size
Here is calculation for the cross-rate currency pairs:
(open price – closing price) × base currency rate × closing price × contract volume × lot size