Magento – 4 Spalten

With the catalog.xml:
LINK: How to change the number of columns in Magento catalog grid

LINK: Magento – 4 Spalten / Columns bei der Gitter / Grid Ansicht im Frontend

Open
app/design/frontend/default/YOURTHEME/catalog/product/list.phtml
and the below code.

$row_count = 5 //or whatever you want
$this->setColumnCount($row_count);