File Extension SPW File Format Worksheet (SigmaPlot) SPW stands for Worksheet (SigmaPlot). This was last updated in March 2012 By Margaret Rouse Browse File Extensions Alphabetically: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ask a Question. Find an Answer. Ask your peers a question about this file extension. Ask a Question Go to Excel worksheet by clicking on cell Deleting all formulas in a worksheet when unprotected in VBA code Copy and paste in Excel using Visual Basic scripting?