Mobile data plans typically provide a fixed amount of data transfer each month for a specific price. For example, you might pay a flat rate for up to 5GB of data transfer in a month. If you exceed your quota, you typically pay per megabyte of overage. Most wireless carriers provide online calculators based on similar estimates of the number of bytes you transfer for activities such as sending email, downloading files and streaming video. However, it's best to closely monitor your account and track your daily usage to ensure you don't exceed your monthly stipend.
Sending and Receiving Email
Wireless carriers estimate the size of an email to be between 10KB and 20KB without any attachments. This means you could send between 250,000 and 500,000 emails in a month and remain within your 5GB limit. When you attach a picture to an email, it raises the size estimate to 300KB per email, and lowers the number you can send to between 16,000 and 17,000. If you took your picture with 2240x1680 resolution, you would be limited to about 5,000 emails.
Surfing the Web
If you spend your time surfing the Web, browsing and reading Web pages, your 5GB monthly limit would enable you view about 10,000 Web pages in a month, or a little more than 300 hours of online surfing.
You'll have to limit yourself to about 2 1/2 hours a day of listening to music from an Internet radio station if you want remain within a 5GB limit for the month. If you prefer to download songs to your computer, 5GB gives you enough bandwidth to download anywhere from 700 to 1,200 songs each month.
Streaming a non-HD video over 3G uses from 125MB to 250MB per hour, which means you could stream between 40 and 80 hours a month, or about one to two hours per day. Streaming HD video or streaming over 4G uses from 300MB to 350MB per hour, giving you about 15 to 17 hours of HD streaming per month, or about 30 minutes of HD streaming per day.
Video Calls and Navigation
Video calls will consume more data than any other online activity. A video call transfers between 480MB and 720MB per hour, depending on the resolution you choose. That limits you to about seven to 10 hours of video calling per month. If you use your device as an online navigation system, you can drive and navigate about 1,000 hours each month before you exceed your quota.
Checking Your Actual Usage
You can check your actual data usage for the month on an AT&T device by dialing "_DATA#"; on Verizon by dialing "#DATA"; and on Sprint by dialing "_4". Calls to your carrier from your mobile device don't typically count against your monthly talk limits.