What internet speed do you need for 4K streaming?
Netflix recommends 15 Mbps or higher for 4K, and YouTube recommends 20 Mbps sustained. Aim for about 25 Mbps for each 4K screen that may run at once, so there is headroom when the connection fluctuates.
What the streaming services recommend
| Service | Quality | Recommended speed |
|---|---|---|
| Netflix | HD (720p) | 3 Mbps or higher |
| Netflix | Full HD (1080p) | 5 Mbps or higher |
| Netflix | Ultra HD (4K) | 15 Mbps or higher |
| YouTube | HD 1080p | 5 Mbps sustained |
| YouTube | 4K | 20 Mbps sustained |
These are the figures the services publish in their help centres. They describe a steady speed, so a connection that averages 20 Mbps but dips to 8 Mbps can still buffer.
Why our test uses 25 Mbps
SpeedUp's verdict for 4K streaming is a rough guideline, not an official standard. It shows Smooth at 25 Mbps or more, HD only from 8 to 25 Mbps, and Will buffer below 8 Mbps. We use 25 Mbps because it sits above both services' recommendations and leaves room for Wi-Fi losses and a few other devices online.
How many 4K screens at once
| 4K screens at the same time | Minimum (service figures) | Comfortable |
|---|---|---|
| 1 | 15 to 20 Mbps | 25 Mbps |
| 2 | 30 to 40 Mbps | 50 Mbps |
| 3 | 45 to 60 Mbps | 75 Mbps |
Add your other activities on top. A video call or a game download at the same time uses its own share.
If 4K still buffers on a fast connection
Streaming apps lower the picture quality when the speed drops, so a stream that stays blurry or keeps stopping usually has a cause other than your plan:
- Weak Wi-Fi to the TV. Smart TVs often sit far from the router. A cable to the TV, or a closer access point, is the most reliable fix. See how to fix slow Wi-Fi.
- Your subscription. 4K needs a plan that includes it, plus a TV and app that support 4K.
- Other devices using the line. A big download or cloud backup can squeeze the stream, especially if the router queues badly. See bufferbloat.
- A VPN or relay service. These add distance and can lower speed.
- The service itself. Busy evenings can slow a particular service even when your own line is fine.
To check your connection, run the SpeedUp test on a phone or laptop in the same room as the TV. If that shows a good speed and the TV still struggles, the problem is on the TV side.