Every Carpet Cleaning company will have their own price list or pricing structure, it is a competitive market and you may be able to get a discount off their list prices - but only if you ask! The two most common ways though are by the square foot and by the room.
We've noticed very few companies publish their cleaning prices on the internet or anywhere else for that matter, which makes it difficult for people to get an idea of how much the service is going to cost. By requesting a quote, you can get a more accurate idea of prices for your particular area.
When you ask for a quote for carpet cleaning make sure you request the total cost in order to get an accurate price. Cleaning companies will often quote a general rate from their price list without asking for the specific details. It's always best to fully explain what you need in order to get the true price. For example, is the carpet or rugs heavily or lightly soiled?
Also don't forget that carpet cleaning prices vary widely by area, so make sure the cleaning company knows exactly where you live when they quote your price.