This question is asked by thousands of people a month and the answer is never clear. Unlike stocks, real estate, commodities and other more popular assets, domain names have many x factors which contribute to value.
Some of these factors are tangible such as the elements of the domain name (dictionary word, three letter dot com, etc) but the most valuable factors are intangible. A seller’s relative value of money, a buyer’s need for the domain, the buyer’s relative value of money etc.
Many articles and tools exist to help measure how much a domain name is worth. Some articles have value. Some tools have value. But there is no magical formula accurate enough to broadly value domain names in general. In fact, it’s mathematically impossible due to the numerous amount of x factors included in the foundational data set of comparison.