How much does it cost to change your last name?

I wanna change my last name because i really dont like it does anyone know how much it cost's?How much does it cost to change your last name?In the United States it cost about a hundred bucks.How much does it cost to change your last name?first in the uk you have to be over 18 to not have to have parents permission, i just had my 18 yr old surmane changed, just made an appointment with a solicitor %26amp; it cost 50, if you go through the court it is cheaper but more hassle, only took 10 minutes %26amp; it was all done %26amp; legal