While it is not the lowest you can find out there, it is more than fair for users as it is set at 1%.
King Dice offers a low house edge for the players playing in the site. This method has been used by other sites in the past and has proven to be a healthy way to run a Bitcoin dice site as it provides the tools to operate a site without worrying about high losses. You can even invest in the site and make money that way through, the way that works is that you provide the site with XX amount of Bitcoins and then you get a monthly share of the dividends dependent on your share of the house bankroll. Their current bankroll is around 150 Bitcoins, which is more than many other sites have and provides a safe place to play.
The site currently has a healthy “house bankroll”, which is the amount of Bitcoins they have in their storage to pay winning players.