[un_pogaz]

@JSWolf Yep? Very incorect.

Try that:

python:
from calibre.gui2.library.bookshelf_view import width_from_pages

def evaluate(book, context):
    val = book.get('#pages')
    try:
        pages = max(0, int(val))
    except Exception:
        return '0.4'
    return str(width_from_pages(pages, num_of_pages_for_max_width=1500))

EDIT: Ah, seem you fix it on own.