This indicator is based on the Average True Range.
You can use the following MT4 indicator (attached bellow) named ATR Monitor to check instantly what the Average True Range is in Pips for the last 9 periods for up to 10 currencies.
You can use the above to check how the volatility changes over time by seing how the Average True Range (ATR) values change over the time lags.
When you attach the indicator to the chart you get the following options
Period : Averaging period for calculation of the Directional index
TIP: Setting the period equal to 1 will give how many pips the given instrument had moved the given period
Currency #: Which currency pair to be analysed at position #
This indicator is also available in Multi Time Frames Version. Check it out here Average True Range Monitor Multi Time Frame Version.