http://www.numion.com/calculators/
Traffic in megabytes per day =
UsersPerDay * ResourcesPerUser * ResourceSize / 1048576
Traffic in gigabytes per month =
UsersPerDay * ResourcesPerUser * ResourceSize * 30.41 / 1073741824
Traffic in megabytes per visitor =
ResourcesPerUser * ResourceSize / 1048576
Minimum bandwidth needed =
UsersPerDay * ResourcesPerUser * ResourceSize * 8 / (86400 * 1000)
Maximum bandwidth needed =
UsersPerDay * ResourcesPerUser * ResourceSize * 8 * 3 / (86400 * 1000)
Users per second =
UsersPerDay / 86400
Users per day = (input field)
Users per month =
UsersPerDay * 30.41
Resources per second =
UsersPerDay * ResourcesPerUser / 86400
Resources per day =
UsersPerDay * ResourcesPerUser
Resources per month =
UsersPerDay * ResourcesPerUser * 30.41
Download time per page =
86400 / (UsersPerDay * ResourcesPerUser)
Simultaneous visitors =
UsersPerDay * ResourcesPerUser / 1440