Streaming Bitrate and Upload Speed: What You Actually Need

Bitrate is the amount of data your encoder spends describing the picture each second, measured in kilobits or megabits per second (kbps or Mbps). The encoder - either software such as OBS Studio (the free, open-source app most streamers use) a dedicated block on your graphics card, or the encoder built into a hardware switcher such as the ATEM Mini Pro - has that fixed budget and nothing more, so every frame is a negotiation about which details survive.

That is why motion is the enemy. A talking head in a fixed frame barely changes between frames, so the budget goes a long way and the picture stays clean. A fast game, a camera pan or falling confetti forces the encoder to re-describe most of the screen sixty times a second, and when the budget runs out the picture goes soft and blocky. The same bitrate that flatters a podcast will smear an action game.

Bitrate is also a ceiling rather than a quality dial. Resolution and frame rate decide how many pixels the budget has to cover; bitrate decides how well it covers them. Streaming at 1080p60 on a budget that only comfortably covers 720p produces a worse picture than the honest 720p stream, which is why the platform tables below pair every resolution with a number.

Both platforms publish their own encoder guidance, and it is worth reading the primary source rather than a forum thread. Twitch (Amazon's live-streaming platform) sets out its figures in its broadcasting guidelines; YouTube's live figures live in its live encoder settings documentation. The headline numbers:

Two footnotes matter. First, Twitch's 6,000 kbps cap applies to the standard H.264 path every account gets; the newer Enhanced Broadcasting mode, set up from inside OBS Studio, hands encoding decisions to Twitch's servers and can unlock higher totals with newer codecs where a channel qualifies. Treat 6,000 as the dependable planning number. Second, the two platforms differ in what happens after your stream arrives. YouTube re-encodes every stream into a ladder of quality options, so a viewer on a weak connection always has a fallback. On Twitch, those lower-quality options are not guaranteed on every channel - a reason not to max out your bitrate simply because your connection can: viewers who cannot keep up may have no lower rung to drop to.

Broadband is sold on download speed, but a stream travels the other way, and most UK connections are heavily asymmetric. The common fibre-to-the-cabinet product is sold as 80/20: up to 80 Mbps down but only around 20 Mbps up, and the upstream figure degrades with distance from the cabinet just as the downstream does. Full-fibre products change the picture dramatically, with upload speeds that finally match the marketing, but plenty of streamers are still working with a fraction of the upload their download suggests.

A stream also uses that upload differently from anything else you do. A photo backup or a big email finishes; a stream occupies its slice of the upstream continuously for hours, and everything else in the household - video calls, cloud sync, game clients quietly uploading telemetry - competes for what is left. The number that matters is not what your line can burst to, but what it can hold, at the time of day you actually stream, while the rest of the house does what it normally does.

A working rule that keeps streams stable: your total stream bitrate - video plus audio - should use no more than about 70 to 75 per cent of the upload speed a wired speed test measures. The gap is not waste. Speed tests measure a short burst under ideal conditions; a stream is a marathon that has to survive the evening peak, a housemate's video call and your ISP's bad moments, and it fails visibly the instant the connection dips below what the encoder is sending.

Worked through: a full-quality Twitch stream is 6,000 kbps of video plus 160 kbps of audio, call it 6.2 Mbps. Divide by 0.75 and you want a shade over 8 Mbps of measured upload. A 12 Mbps YouTube stream at 1080p60 wants around 16 Mbps. Run the test over ethernet at the time you would normally go live, not at a quiet lunchtime, and treat the lowest of three results as your number.

Live video has no ability to catch up. A file upload that stalls for two seconds simply finishes two seconds later; a live encoder that cannot deliver its output has to throw frames away, and every viewer sees the stutter at once. That is what the dropped-frames counter in OBS Studio is reporting: moments where the connection could not carry what the encoder produced.

This is why a steady 10 Mbps connection is a better streaming line than a spiky 50 Mbps one. Consistency beats headline speed, and the usual source of inconsistency is not the ISP but the last ten metres: wifi. Interference from neighbours, microwaves and the house's own devices produces exactly the brief dips that live video cannot tolerate.

CBR (constant bitrate - the encoder spends the same budget every second regardless of what is on screen) is what both platforms ask for in their own documentation, and it is the right answer for live work. VBR (variable bitrate) is the smarter choice for files you upload later, because it saves data on still scenes and spends it on busy ones. Live ingest servers, though, are built around a predictable, steady flow - and a VBR spike during a busy scene is precisely the surge a marginal upload cannot absorb, at precisely the moment the picture matters most.

Set CBR, set the keyframe interval to 2 seconds, and let the bitrate number do the quality work. If your encoder offers a constrained VBR mode for live use, it exists for special cases; the platform defaults are CBR for a reason.

Treat these as starting points rather than verdicts. Watch the dropped-frames counter across your first few sessions; a clean hour at your chosen settings is worth more than any table, and a persistent 1 per cent drop rate is your cue to step the bitrate down before you fight the encoder settings. If you run a multi-camera setup through a hardware switcher, the same budget rules apply to whatever single feed leaves the encoder - our ATEM Mini multi-camera guide covers that chain, and clean audio at a sensible level (see our gain staging explainer) matters more to viewers than any resolution jump.