I'm trying to start my own cleaning business but not sure how to charge per square footage? Is cleaning products included in my services or do I charge per product used?

Will this be commercial or residential cleaning? And no, you don't charge for the products you use, that is supposed to be inclusive in your estimate, based on square footage of the house, or business. You quote an hourly rate, normally it is $20 per hour where I live in Ontario. You will have to determine how long a two bedroom house, or 3 bedroom house will take you, taking into consideration the number of floors to be vacuumed. Dusting normally takes a long time so I don't have my cleaner do that, I do it myself.

My house is a bungalow, 1200 sq. ft. 2 bedroom, so it takes my cleaner 2 hours to vacuum, tidy kitchen, clean bathroom, scrub shower stall and wash the floors. To give you a rough idea.

You don't charge for products. When you calculate your price (per hour, per room, or whatever), you should have those costs already included into the pricing.