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What bitrate means
Bitrate is the amount of data your video or audio uses each second. It is set by the video file or by the program that is sending your stream.
A higher bitrate usually means more detail, but it is not always better, because the type of codec (the method that compresses and plays video) and what is on the screen also matter.
Some bitrates stay the same all the time (constant bitrate), while others change depending on how busy the scene is (variable bitrate).
What bandwidth means
Bandwidth is how much your internet line can actually carry at that moment. You cannot set it yourself, it depends on your network.
It can change because of Wi-Fi quality, network traffic, or even how far you are from the router.
A speed test tries to measure it. If the video bitrate is higher than your download speed, it will buffer. And if you are streaming live and set your bitrate higher than your upload speed, frames will drop.
Why both show up as Mbps
Both are measured as “data per second”, so they use the same unit: Mbps. That is why many people mix them up.
The easy way to see it: bitrate is the demand, bandwidth is the supply.
When you are streaming live, things work smoothly if your bitrate stays well below your upload speed. If it is too close, even a small drop in internet speed can cause stutter, so it is safer to leave extra room.
Bitrate vs bandwidth using analogy
Both matter when you watch videos and when you stream live. For watching, your download speed is what counts. For live streaming, it is your upload speed.
When demand is too high for fixed capacity
- Think of bandwidth and bitrate like a highway. The number of lanes is your bandwidth, and the cars on the road are your bitrate. If too many cars try to use the highway at once and there are not enough lanes, traffic slows down or stops.
- That is like trying to watch a 4K video on youtube on a slow connection. The video keeps buffering because the road is too crowded for that much traffic.
When capacity itself shrinks from signal loss or congestion
- Another way is a faucet filling a bucket. The faucet size is bandwidth, and the water you let out is bitrate. If the water pressure is weak that day, the faucet can only let out so much, even if you want more.
- That is like when your network slows down because the signal is bad or too many people are online at the same time.
In short, bitrate is the demand while bandwidth is the supply. Problems happen when demand is too high or when supply drops.
Bitrate needed for streaming
Different platforms share their own numbers to guide people:
- Netflix: About 5 Mbps for HD (1080p), around 15 Mbps or more for 4K. It also needs a stable line, not just a speed test spike.
- YouTube Live: For 1080p60, it usually suggests 4–10 Mbps depending on settings. Higher resolutions need more.
- Twitch: For 1080p60, most people use about 6Mbps. This may change with region or account.
These are rough numbers, and what you really need can change with the codec, how busy the picture is, and how steady your internet is.
Does higher bitrate always mean better quality?
Not always. Newer codecs like AV1 can keep the picture clear even with lower bitrates, while older ones like H.264 usually need more.
So, a 6 Mbps AV1 video may look similar to a higher bitrate H.264 video.
It also depends on what is happening on screen. A calm scene may look fine at a low bitrate, but a fast action scene usually needs more.
Keep some space below your internet speed
Most streaming services today can automatically change video quality (like the 'Auto' option on YouTube) when your download speed goes up or down. This is called adaptive bitrate streaming.
But if you are the one streaming live, what matters is your upload speed. Do not set your stream bitrate too close to your maximum upload, because small drops in speed can cause lag.
Source: Reddit (ELI5 Can someone explain the difference between Bitrate and Bandwidth. Both are in Mbps and important in streaming)