To calculate the bandwidth for an EC2 instance based on Google Analytics data, you will need to follow these steps:

- Log in to your Google Analytics account and navigate to the “Audience” section.
- Select “Overview” and set the date range for the period you want to analyze.
- Look for the “Sessions” metric, which represents the total number of sessions during the selected period. This represents the number of times visitors accessed your website.
- Look for the “Pageviews” metric, which represents the total number of pages viewed during the selected period. This represents the number of pages that were served to visitors.
- Look for the “Avg. Page Load Time” metric, which represents the average amount of time it takes for a page to load. This represents the amount of time it takes to transfer the page data from the server to the visitor’s browser.
- Calculate the total amount of data transferred by multiplying the total number of pageviews by the average page size, which can be estimated based on the average page load time. For example, if the average page size is 1 MB and the average page load time is 2 seconds, the estimated average transfer rate would be 0.5 MB/s. If you had 100,000 pageviews during the selected period, the estimated amount of data transferred would be 100,000 x 1 MB = 100 GB.
- Divide the estimated amount of data transferred by the number of seconds in the selected period to get the average bandwidth usage per second. For example, if the selected period was one month (31 days), the average bandwidth usage per second would be 100 GB / (31 x 24 x 60 x 60) = 0.12 MB/s.

Note that this is an estimate based on the Google Analytics data and the assumed average page size and transfer rate. The actual bandwidth usage may vary based on factors such as the size and complexity of your website, the number of visitors, and the usage patterns. To get a more accurate estimate, you may need to use server monitoring tools or consult with your hosting provider.