A single point size is a profit obtained when the price moves one point for a position of a specified volume. The formula to calculate is:-
Point Size = (10-Digits) × ContractSize
Whereas we know the contract size of 1.00 standard lot for any forex pair is always 100,000 unit currency. Therefore, the Point Size of any 5 digits forex pair e.g. EurUsd is calculated as followed with respect to its quote currency:-
PointSizeEurUsd = (10-5) × 100,000 = 1.00 USD
That means when you buy 1.00 lot EurUsd, every point movement (movement of every 0.00001) is exactly profit or loss of 1.00 USD.
Meanwhile, the Point Size of any 3 digits forex pair e.g. UsdJpy is calculated as followed:-
PointSizeUsdJpy = (10-3) × 100,000 = 100.00 JPY
That means when you buy 1.00 lot UsdJpy, every point movement (movement of every 0.001) is exactly profit or loss of 100 JPY.