I would like to start a commercial cleaning business. I have worked for others for to long. What I mainly need to know is how to bid a cleaning job on houses that start around 3000 to 5500 square ft.

That is up to you to determine bidding. Look at all your costs, taxes, insurance, licenses, bonding etc, labor costs, auto costs. Then put in a profit factor.

Have you ever worked doing this before long enough to know what is involved, and what the other places charge?

Amazing how many people think its so easy to start a business they probibly never worked in before.

This is a VERY competitive field... by people how know EXACTLY what it costs to run the business and pay the people... and not overbid themselves out of jobs or underbid themselves out of business.

THey have the advantage of experience... something you won't have, and will make many possibly customers hesitant to go with the unknown and unproven.