The market price of a house is calculated using Comparative Market Analysis. CMA compares your house to similar houses in the area to determine its value. However, while evaluating the asking price of a home, it is important to know that the price listed is many times based off of more than its true market price.
The listed price of a house is often not reflective of only its market price, but is also calculated by what the seller paid, the improvements that have been made, and how much in addition the seller needs for their next house. It is rare for sellers to get their own appraisal of their house. They may do this to verify its value, but in most cases appraisals are done through banks for mortgage purposes.
Therefore, the market price of the house is sometimes actually lower than what the seller is asking for. If you know the appraised value, you should offer to pay the lower market value of the house.
It is a very different scenario if you are looking to buy a new house. There is not as much room for bargaining the price of houses that were just built. In this case, the builders set the price based off their construction expenses and the asking price is often non-negotiable.
Each case is different and so there is no specific rule guiding buyers how to calculate an offer in response to a seller's asking price. Despite this, it is always helpful for buyers to keep in mind the market price of the house when making an offer on their new home.