Think about how your household actually uses the internet
Before any numbers, think about real usage. A retired couple who email and watch iPlayer need something very different to a family of five with teenagers gaming, parents on video calls, and a 4K TV in the living room.
Rough guide: what different speeds support
10-30Mbps: Basic browsing, emails, and standard definition video. Fine for one or two people, not for simultaneously demanding tasks.
30-60Mbps: HD streaming on a couple of devices at once, regular video calls, general browsing for 2-3 people.
60-100Mbps: The sweet spot for most families. Multiple HD or 4K streams, someone working from home, gaming, all manageable at once.
150-300Mbps: Large households, multiple heavy users, home businesses, frequent large uploads.
500Mbps-1Gbps: Future-proofing, professional content creation, or households where everyone runs demanding applications simultaneously.
Count devices, not just people
Smart TVs on standby, phones on WiFi, smart speakers, security cameras, thermostats, all draw on your bandwidth even when nobody is actively using them. A modern household of two people can easily have 15 or more connected devices.
Do not forget upload speed
If you work from home and do lots of video calling, upload matters just as much as download. A Zoom or Teams call needs around 3-5Mbps upload per participant.