Alongside category, length is the next most important element of an ethernet cable. Partly that’s obviously just a question of how far you need the cable to reach, but it also relates to speed and performance. Speeds can drop off over longer distances, especially with the more modern cables – for example, that Cat7 speed of 100Gbps is only up to a range of 15m, while a Cat5e maintains its highest speed for up to 100m. Still, the average consumer isn’t likely to be cabling anything anywhere 100m, and even 15m is probably longer than many people will need for their homes, so we wouldn’t worry about this too much – just try to avoid buying a 50m cable when you only need it to stretch across one room.