CHMOD Calculator is a free, portable app that lets you check boxes which tell you what number to use to CHMOD a file for access.
It's very simple to use. You have two sets of three rows; Owner, Group, and World. Under each of these, you will find Read, Write, and Execute. Check the boxes needed, and it will calculate the CHMOD for you.
CHMOD Calculator is a unique utility for those who need to calculate CHMOD on a regular basis. Although it's free and portable, those who only need this occasionally can also find online calculators as well.