Question: irfanview how to batch resize?
Answer: Download the free software called IrfanView and IrfanView plugins (www.irfanview.com). ... 
In Irfanview Go to File (top left) and select Batch conversion/Rename.
In the Batch Conversion Window 'Add' the images you would like to resize or 'Add all'. ... 
Specify an Output Directory (on the left).