Range chart control limits are calculated as follows:
Control Limits calculated
from 
Control Limits calculated from 


NOTE: If subgroup size is variable, m is replaced with m_{i} for i^{th} subgroup limits. When subgroup size is variable, the control limit values will not be the same; therefore, the chart may display `city skyline' type control lines (when subgroup size is from 2  25).
Subgroup Range
Lower Control Limit (LCL) (optional)
Upper Control Limit (UCL) (optional)
Warning lines (optional)
Lower Control Limit (LCL)
Upper Control Limit (UCL)
Center Line (CL)