Let’s say your website is getting you 1000 usd from adsense. And these earnings are constant from the past year. And you don’t have any marketing/time invested in it. It just keep sending you money.

The PER (price earning ratio) would be 5.

That means you could sell a website for the money you would get from it in the next 5 years.

So, the selling value of a website would be: 1000 usd x 12 months/year x 5 years = 60,000 usd, money you could get now.

Of course, selling value of a website depends on other various factores. The recession, for example. Right now, there are companies in the market with PER 2, or PER 1. That means that if you buy the stocks, you should have 100% profit in the first year.