See this FAQ for Skype bandwidth requirements:
The question was, how much data does a call use, not bandwidth. These are two different, but related things. Bandwidth is how big of a pipe you need to sustain a good quality, call. Data is the number of bits or bytes you move through that pipe. The call may only use the full bandwidth every once in a while, e.g. if there is a lot of movement in the picture. Skype recommends 300kbps for a video call, both up and down. If you use the full bandwidth, that would consume 60x300k = 18Mb of data in a minute, or 1.08Gb in an hour. And that's only one way, so a two-way video call would use 2.16Gb per hour maximum. That's the theoretical maximum. Is there anyone that knows what a typical video call would use, e.g. average of half the bandwidth? A quarter?
I would suggest that you've disproved your own argument that knowing how much bandwidth is required doesn't tell you how much data will be used. You simply multiple the bandwidth by the amount of time you want to reference and come up with data use for that time period.
I agree with your math but I think it worth mentioned that the 2.16 Gb you calculated is gigabits. Data plans are typical in bytes, not bits, and the 2.16 Gb is .27 GB, or gigaytes. It may be more meaniful yet to state that as 276 megabytes per hour.
Now that we've crunched the math, let me speak of real world experience. The fact is that video call data use will vary tremendously depending on a numer of factors, those including actual bandwidth available and both ends of the call, the quality of the connection between the contacts on the call, the specific webcams in use and the amount of processing power that's available.
When I'm on a 1920x1080p HD call the typical bandwidth used is ~650 kB/s. A 720p call will run around 350 kB/s, and a good 640x480 SD call ~150 kB/s. I've also had calls where conditions only allow 320x240 and data used can be as litle as 15-20 kB/s. You can do the math if you want data use per minute or hour.
Here's the bottom line....the bandwidth requirements outlined by Skype will tell someone what kind of results they can expect with bandwidth they have available. You can't expect HD video if you only have a .2 mb/s upload connection to the Internet. But to know how much you actually use, I suggest a utility like DU Meter. It will let you monitor your data throughput real time, and also keep track of how much you've used over a given time period.
Let's see....thus far this month I've used 35.64 GB upload @ download; 2.11 GB in the past 24 hours; and 12.8 mB so far today. It's clear as a bell.
I know I am a tad late to the party here but I took the liberty to work out the data usaged based on the recommended bandwidth ammounts set by the following FAQ page:
100kbps/100kbps = 200kbps total.
200kbps = 25KB/sec
25KB/sec = 1.5MB/min
1.5MB/min = 90MB/hour
Video Calling/Screen Sharing (Low Quality):
300kbps/300kbps = 600kbps total.
600kbps = 75KB/sec
75KB/sec = 4.5MB/min
4.5MB/min = 270MB/hour
Video Calling (High Quality):
500kbps/500kbps = 1mbps total.
1mbps = 125KB/sec
125KB/sec = 7.5MB/min
7.5MB/min = 450MB/hour
Video Calling (High Definition):
1.5mbps/1.5mbps = 3mbps total.
3mbps = 375KB/sec
375KB/sec = 22.5 MB/min
22.5MB/min = 1.35GB/hour
Group Video (3 People):
2mbps/512kbps = 2560kbps
2560kbps = 320KB/sec
320KB/sec = 19.2MB/min
19.2MB/min = 1.15GB/hour
Group Video (5 People):
4mbps/512kbps = 4608kbps
4608kbps = 576KB/sec
576KB/sec = 34.5MB/min
34.5MB/min = 2.07GB/hour
Group Video (7+ People):
8mbps/512kbps = 8704kbps
8704kbps = 1088KB/sec
1088KB/sec = 65.2MB/min
65.2MB/min = 3.91GB/hour
I hope this helps anyone with a data usage enquiry.
Many thanks for all of your help with this.
I have a related problem that you may be able to help with?
I have to buy a device to enable my kids (young and requiring assistance to operate devices) to Skype video call me in the UK from the USA. In practice there will be video calls 3 times per week for a total of about 2 hours (at most). I do not want the device used for anything else by the kids or anyone else.
Sadly the kids mother is "less than helpful" and is likely to use the cellfone signal all the time rather than the free wi-fi option.
Which device would you recommend and which cellfone service?
thanks in advance