3G 250mb of data?

It's not so much hours as how much data. Every web page, every email received or sent, every app download or iTunes or iBook purchase will take some data - thus the answer to your question is that it depends how you use your iPad while it's on the data network.

As a bit of a guide, a typical ebook is about 500Kb (half of 1 megabyte), but an iPad app from the app store could take a tenth of your monthly data or more just to download.

You will get warnings about your data use so you don't exceed the plan, and you can swap between 250 and unlimited plans as and when you wish.

Not how many hours, but how much data.

650 MB is a single uncompressed audio CD.
10 audio CDs can be compressed in standard compression rate for iTunes store music on a single standard audio CD. So imagine 3 audio CDs a month if you had no web usage, and just use iTunes store purchases.
2000 MB is a typical MP4 2 hour movie from the Apple Store.

Tough question. Get a slow enough connection speed and that can last you all month! Get a fast enough speed and it will only last a few hours.

Remember that you will only be using 3G if you are not able to connect to a Wi-Fi connection. You can always browse the app store, view some web pages, send e-mails, and then when you get home THEN download apps and do the bigger things with your Wi-Fi connection.

Virgin Mobile's Broadband2Go uses this table to estimate usage.


http://www.virginmobileusa.com/mobile-broadband

If your on 3G not wifi, you also have to remember that downloading new apps, app updates and things like this all count towards your data use. Probably even just browsing the app and iTunes store too as there is no way to differentiate the data being used.

That 250 megs can go quick. I had an fishing app update last night that was 52 megs alone.

The estimate the website above uses would give you 10-13 hours of web browsing roughly.

I found this from ATT:

What Can You Do With a 250MB Data Plan?

Let us look at how much data is typically needed for the basic things we do. For example, reading emails, browsing the web, downloading songs, and watching videos. Here is the breakdown of data usage/requirement.


Size of an email: ~10KB
Size of a typical webpage: ~150KB
Size of a single page in word/pdf: ~35KB to 100KB
Size of a photo from facebook/picassa: ~60KB
Size of a presentation with 10 slides: ~1MB
Size of a decent photo from a 6MP Digital Camera: ~1.5MB
Size of a ten minute Skype call: ~5MB
Size of an average eBook: ~2MB
Size of a 5 minute MP3 song: ~5MB
Size of a 3 minute You Tube Video: ~2-5MB
Size of a 30 minute show on Hulu: ~250MB(?)