The following formula can be used for swap calculations:
Swap = Swap long/short × number of days × lot size
For Example:
You opened a buy (long) order of 1 lot EURUSD with a Standard Account on Tuesday at 15:00 and closed it on Thursday before 24:00 or 12:00 AM.
Calculation:
Lots: 1
Swap Rate: -13.472 points
Number of Days: 5
Standard Swap on Tuesday at 12:00 AM: 1
Triple Swap on Wednesday at 12:00 AM: 3
Therefore,
Swap = -13.472× 4 × 1 = -53.888 USD
This charge is negative and is deducted from your trading account balance. If it were positive, no swap charge would be applied.
Note that this is just an example and this can vary depending on the instrument.