How much mbits download do I need?

How much mbits download do I need if I simultaneously watch online netflix and watch my parents also streming tv would be enough 250mbits?

50mbits are enough, as long as it works silly

A higher contractually guaranteed quota usually makes sure that you have a certain minimum bandwidth and that you do not "fly out" in the event of a power breakdown in the network.

However, what you should also be aware of is your ping (latency), as this indicates the transmission time of individual packets, and, if too high, you ruin your beautiful bandwidth.
If you have a Fritz box, you can view the latency values directly from the web interface (under the network tools).
At Sonsten there are various online tools such as the https://sourceforge.net/...speedtest/, or, for more precise measurements, a "long - term test. (I still find out.

250 MBit / s should be good enough for that, you probably already get along well with 100 MBit / s.

Note, however, that it depends on what actually arrives at the router with you, that does not always have to agree with the rate agreed in the tariff!