Days required to learn web developement??

Answer 1

That depends on you and your goals.

Answer 2

You can probably understand the basics in a day, but discovering all the different technologies, frameworks, languages and architectures will take you a lifetime, especially if you always want to keep up with the most recent trends.
The speed of learning depends a lot on your own cognitive abilities and how much time you practice. And it's impossibe to say what would be a goal of 100% to learn, when the technology landscape is always changing.