We use the standard formula to calculate the percentage of change for a particular currency pair as follows:
Current Price – Old Price / Old Price * 100
We perform this calculation across 28 Forex pairs for each of the 4 time frames and then group the pairs together to work out the underlying strength of a given currency.
To give you an example, here’s what the calculation may look like for the U.S Dollar (USD):
AUDUSD: -2.1% (+2.1%)*
EURUSD: -3.8% (+3.8%)*
GBPUSD: -1.4% (+1.4%)*
NZDUSD: -3.5% (+3.5%)*
USD Strength = 19%
* We invert positive or negative values when the USD is the quote of a pair, for base pairs the value remains unchanged.