There are many companies on the web offering appraisal services for domain names. Some, such as SwiftAppraisal.com (which is free) perform this function entirely through automated software that checks for certain features, such as the presence of hyphens, total length, or an estimation of the market size. Other sites charge between $10 to $35 for a personal appraisal, which may be more nuanced. The problem with this approach is that every sale of a domain name is completely unique, and ultimately the value of a domain name is worth whatever a buyer will pay for it.

In general, it is worthwhile to look at sales figures for other domains in the same category, but even a cursory glance will reveal that final prices vary widely even for similar names.

However, a general guideline does exist. The most valuable domain names are the .coms, followed by .net, .org and .biz. Single word websites sell for the most money, though not all single words will have the same high value. Concatenated phrases are slightly less valuable than single words, and hyphens decrease the value further. Short words and phrases are preferable.

Not all words have the same commercial potential, and most domain names have no resale value at all. For example, Trucks.com might sell for more than a million dollars; GMCTrucks.com could sell for tens of thousands; Your GMCTrucks.com would be lucky to sell for a few hundred dollars, if at all; and YourSiteForGMCTrucks.com is commercially worthless. So before anticipating massive profit from the sale of your domain name, think about whether the domain name is unique and irreplaceable, like Sex.com (which sold for $12 million) or just a long concatenated phrase with dozens of variations that anyone registering a website could come up with. Also, replacing letters with number, "4" for "for", or using common misspellings lowers the domain name value.

However, long phrases are not always worth less than single words if they are frequent web search terms with commercial value: for instance, FreePhoneService.com is worth more than Grammer.com. Commercial potential is a subjective value, and often not considered enough by domain name appraisers, who may not know the size of the industry covered by the name.

One sure indicator that you have a valuable domain or website is unsolicited offers to buy it. Clearly, if customers are so eager that they make offers without the domain even being listed for sale, it has great commercial potential.

Also, content and links add value to niche-market domain names, and if a site is producing income, it can be sold as an internet turnkey business. This is similar to commercial real estate, where a business with clientele and inventory will sell for much more than an empty storefront. Not only will this increase the value, this method will provide you with income while waiting for a buyer. In addition, the more popular your site is, and the more visitors you have, the more chance a potential buyer will see it.