Internet speed for streaming: what do you need?
The speed on your broadband contract is only half the story. What decides whether the picture runs smoothly is how much actually reaches the TV – at the moment you are watching. Here is how to find out.
Bandwidth in plain English
Bandwidth is measured in megabits per second (Mbit/s) and describes how much data fits down the line at once. Think of a road: more lanes carry more cars, but that is no help if there is a bottleneck at the exit. In a home, the bottleneck is almost always the wireless network.
Guide figures – not guarantees
Large streaming services typically quote roughly the following per stream:
| Picture quality | Typical guidance |
|---|---|
| Standard definition | 3–5 Mbit/s |
| HD | 5–10 Mbit/s |
| 4K | 15–25 Mbit/s |
These are general rules of thumb, not a promise about any particular service. What applies to your subscription is a question for your provider.
Count the whole household
Add up everything that happens at once on an ordinary evening: a TV in the living room, a tablet in a bedroom, a video call and a games console downloading an update. Suddenly four or five things are sharing one connection. So leave headroom – allow for about twice what you think you need.
Measure where the TV is
- Run a speed test on a computer or phone in the same room as the TV.
- Measure once with a cable straight into the router. That shows what is really being delivered.
- Measure at different times – evenings are busiest.
If the result at the router and the result at the TV are far apart, the problem is in the Wi-Fi, not with your broadband provider.
Wi-Fi quality and router placement
- Put the router out in the open and up high, not in a cupboard or behind the TV.
- Concrete walls, underfloor heating and mirrors dampen the signal heavily.
- 5 GHz is faster but reaches less far than 2.4 GHz.
- In larger homes, a mesh system or a cable to the TV can solve the problem.
More on that in Wi-Fi or Ethernet for streaming.
Megabits and megabytes are not the same
Broadband speed is sold in megabits per second (Mbit/s). File sizes are shown in megabytes (MB). One byte is eight bits, so a 100 Mbit/s line moves at most about 12.5 MB per second. That is why a download never shows the number from your contract.
How much data does one hour of viewing use?
| Bitrate of the stream | Data per hour |
|---|---|
| 3 Mbit/s | about 1.35 GB |
| 5 Mbit/s | about 2.25 GB |
| 10 Mbit/s | about 4.5 GB |
| 25 Mbit/s | about 11 GB |
This matters on mobile broadband with a data allowance. On fixed broadband without a cap you can ignore it.
Why is speed not everything?
- Latency is the delay before data arrives. For watching TV it only affects how quickly a channel starts.
- Jitter is uneven delay. A lot of jitter makes the player’s buffer run dry even on a fast line.
- Packet loss means pieces of the stream never arrive. Even one or two per cent shows as stutter.
Wi-Fi is the usual source of jitter and loss. A line that measures 200 Mbit/s over Wi-Fi with drop-outs is worse for TV than a steady 30 Mbit/s over a cable.
A worked example
A household of four on a weekday evening: one 4K stream in the living room (25 Mbit/s), one HD stream on a tablet (8), a video call (4) and ordinary phone use (3). That is about 40 Mbit/s in use at the same moment. With the rule of doubling for headroom, a line that really delivers 80–100 Mbit/s to the home is comfortable. The same family on a 50 Mbit/s line will usually manage, but will notice it when a console starts a large download.
What do the different connection types mean?
- Fibre gives the most even result; the speed you buy is close to the speed you get.
- Cable broadband is fast but shared in the neighbourhood, so evenings can be slower.
- DSL over the phone line depends on the distance to the exchange; check your real speed before counting on 4K.
- Mobile broadband (4G/5G) varies most with signal strength and time of day. Place the router by a window facing the mast.
What if your measured speed is far below your contract?
Measure with a cable, at three different times, and write the results down. Restart the router and measure again. If the figures are still clearly below what you pay for, contact your broadband provider with the measurements – numbers and times make the conversation short.
If it still stutters
Start by switching the router and the device off and on. If that does not help, there is a step-by-step checklist in Troubleshooting buffering. If you plan to evaluate a service at home, you can use your measurements when you run an IPTV test.