Is Sun the biggest planet?

Sun isn't actually planet but star. Really big ball made of gases. Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%). Sun is the biggest object in our Solar System. It's 99.86% of the total mass of the Solar System.

... wikipedia is really grat if you have questions like that; )

The sun is not a planet. If it was, it would be the biggest planet but it's not. Jupiter is the largest planet in our solar system. Jupiter is bigger than all the other planets put together.