Netflix recommends a 25 Mbps speed for streaming in 4K, while amazon needs at least 15 Mbps for the highest quality video. Watching Netflix on one tv will only use about 25 Mbps, so using two tvs at the same time will use around 50 Mbps. If this is more than you were wanting you could always go back to just using one tv or you can buy a new plan with a higher download speed. You can also disconnect other devices that connect to the internet if your speeds are running too slow to stream on two tvs. This was for Ultra HD quality, if you are willing to sacrifice the quality to watch on more tvs or to watch longer before your data plan runs out then you can switch the quality to 1.5 Mbps for streaming SD or 5 Mbps for HD. If you were to change the quality to HD then you would be able to stream on about 10 different tvs if nothing else was connected to the internet. The size of the tv and the brand makes no difference in how much data you are using so it will be the same usage for each tv screen or device. It is good to keep an eye on what devices are being run on the internet if you have a data cap because it will just waste data if you forget about it.