Pip value calculation = Contract Size X position size X price change (FX: 0.00010)

Note: price change is calculated in terms/counter currency, which is the back currency for FX pairs (or Margin Currency for CFDs). This will convert automatically to your account currency in MT4.

To check Contract Size/Margin Currency (MT4): right click any product in Market Watch, then select Specification. See "Contract Size" and "Margin Currency."

E.g.
All FX: 100,000 (units per lot) X position size X pips (0.00010)
All Equity index: 1 (contract per lot) X position size X price change
Energy/Oils: 1000 (contracts per lot) X position size X price change
XAUUSD: 100 (ounces per lot) X position size X price change, etc.