The way percent change is calculated on the StockCharts site is you take the Chg value and divide it by the previous day's close and then multiply by 100.
Calculation: Chg / Prev Close * 100
Keep in mind other websites could use a different calculation so you may find that our percent change value might not match those sources. We recommend checking with the sources you use to learn what calculation they use for percent change.
If you are using BATS real-time data for your charts, the percent change value is delayed by 15 minutes.