If you had glanced at you couldn’t miss the fact that it is free.

Is Ubuntu free to use?

Open source

Ubuntu has always been free to download, use and share. We believe in the power of open source software; Ubuntu could not exist without its worldwide community of voluntary developers.

Is Ubuntu free or paid?

Ubuntu is free as in “costing no money” to use for the default software (there is 3rd party software that can cost money). The only thing Ubuntu costs is the time you invest in getting to learn how it works.