Can anyone guide me on how to estimate the amount of hours for a software project from the requirements provided by the client. Also how to calculate the hourly rate if I'm an intermediate Javascript developer. I've done some small freelance works, and I think my estimations were not correct for those works.

AFAIK everyone gets it wrong. There are so many factors that affect the progress. To get approx estimation , i ask as many questions as possible to client to understand the requirements clearly. I break down the individual page into many components and estimate for that particular component finally i tell the client the sum of all those estimations. Even though i fail to get correct estimation all the time atleast the margin is decreasing. To fix a rate for your work . Analyse the average salary you would get as an employee, you should be making atleast 2x of that amount when you freelance.

Get your estimated hours and make it 3x. It will allow to fill any gap, if there are. You can check rates on upwork, comparing your tech and, experience. That'll give you a good start. Hope this helps you 👍

Thanks guys ☺️