The Currency Strength Bars indicator computes an “index” using an un-weighted geometric mean of several currency pairs. This is similar to the US Dollar Index (USDX) and FXCM’s USDOLLAR. However, it does this, not just for the USD, but for 7 other currencies too. That’s 8 major currencies in total: USD, EUR, GBP, CHF, JPY, AUD, CAD and NZD.
The indicator uses 28 currency pairs to compute this “raw” average strength value.
The indicator normalizes the "raw" strength data with an RSI, and then ranks the 8 major currencies (high to low) according to this value. The results are plotted as a bar (horizontal or vertical). The indicator supports 4 customizable time-frames, which allows strength to be assessed over short, medium and long timeframes.
This indicator is available from my blog and also on the FXCM Apps site.