How do I figure out how long it will take to transfer a 2 gig file over a 56k connection?

1 byte = 8 bits
Giga means 1,000,000,000
Kilo means 1,000

So first we convert 2Gigabytes to 2 Kilobits

2 Gigabytes * 8 = 16 Gigabits
16 Gigabits * 1,000,000,000 = 16,000,000,000 bits
16,000,000,000 bits / 1,000 = 16,000,000 kilobits

Assuming you were able to actually transmit at 56 kilobits per second the formula would be:

16,000,000kilobits / 56kbps = 285,714 seconds

Then to get it to some meaningful time measurement:
285,714 seconds / 60 = 4761.9 minutes

4761.9 minutes / 60 = 79 hours
79 hours / 24 = 3.3 days

So your final answer would be 3.3 days.

Now if you’re on a 56k modem, the upload speed is at BEST 33.6kbps. Which comes out to about 5.5 days.

Your best option here is to burn the file to a DVD and stick it in the mail. It will be a lot faster!