How to calculate value of my site

Good Morning, I am the owner of a celebrity blog and forum, I have seen that its possible to sell website on the internet so I was checking an online tool and I found the value of my site is around $75,000. I really would like to sell it as soon as possible. Can you guys give me a confirmation about the metric and system used to evaluate my website? Please take a look to http://www.valueofwebsite.us Thank you a lot!