What bitrate actually is
Bitrate is how much data your video spends per second, in kilobits (kbps) or megabits (Mbps). It's the budget your encoder gets: too low and fast motion smears into blocks; comfortably high and quality is limited by resolution and codec instead. That's why recommendations depend on resolution and frame rate — more pixels per second need more bits per second.
Upload vs live streaming
Uploads (YouTube) can afford generous bitrates — the platform re-encodes everything anyway, and a higher-quality source survives that re-encode better. Live streams are different: every kilobit must fit through your upload connection in real time, and Twitch's standard guidance tops out around 6,000 kbps. Rule of thumb: your consistently available upload should be about 25% above the stream's total bitrate.
The file size formula
Size in GB = (video kbps + audio kbps) × seconds ÷ 8 ÷ 1,000,000. One hour at 12,000 + 384 kbps ≈ 5.6 GB. The reverse tab of this calculator runs the same formula backwards — handy when a course platform or email gateway gives you a hard size limit.
Honest caveats
These numbers assume H.264, the safest default. HEVC or AV1 can look as good at roughly half the bitrate. And bitrate is a ceiling, not a guarantee — a noisy, shaky source eats bits fast, while clean footage looks great below the recommendation.
FAQ
Good bitrate for 1080p?
8,000 kbps at 30 fps, 12,000 kbps at 60 fps for YouTube uploads; ~6,000 kbps for Twitch 1080p60 streams.
And for 4K?
40,000–60,000 kbps depending on frame rate (SDR upload).
Is higher always better?
No — past the recommended range you mostly get bigger files, slower uploads and no visible gain.
How big is an hour of 1080p60?
About 5.6 GB at recommended rates.
What upload speed do I need to stream 6,000 kbps?
Roughly 8 Mbps of stable upload — headroom matters more than peak speed.