Average True Range Trailing Stops Strategy Typically, the Average True Range (ATR) is based on 14 periods and can be calculated on an intraday, daily, weekly or monthly basis. For this example, the ATR will be based on daily data. Because there must be a beginning, the first TR value is simply the High minus the Low, and the first 14-day ATR is the average of the daily TR values for the last 14 days. After that, Wilder sought to smooth the data by incorporating the previous period's ATR value. Current ATR = [(Prior ATR x 13) + Current TR] / 14 - Multiply the previous 14-day ATR by 13. - Add the most recent day's TR value. - Divide the total by 14