What the number describes
A 10 Mbps video spends ten million bits on every second, on average. Across 60 seconds that is 600 million bits — 75 MB — which is why file size is simply bitrate × time ÷ 8. Encoders distribute those bits unevenly: simple scenes get fewer, busy scenes more, and the average lands on the target.
Quality depends on content and codec
Two videos at 8 Mbps are not equal: a static interview is pristine while a handheld shot of a crowd shows artefacts. Codecs shift the entire scale as well — H.265/HEVC reaches H.264 quality at about 40% fewer bits, and AV1 at roughly half, though encoding takes longer and older devices may not decode it in hardware.
Recommended bitrates
- 720p30: 2.5 Mbps · 720p60: 5 Mbps
- 1080p30: 5 Mbps · 1080p60: 8 Mbps
- 1440p60: 16 Mbps
- 4K30: 25 Mbps · 4K60: 45 Mbps
- Live streaming 1080p60: about 6 Mbps (Twitch recommends 6,000 kbps with an 8,500 kbps ceiling)
Variable, constant and quality-based encoding
CBR holds the bitrate steady, which many live platforms require. VBR spends more where needed and less elsewhere, giving better quality at the same average. CRF/CQ targets a quality level and lets the bitrate float — ideal for archives, where consistent quality matters more than a predictable size. For a fixed size limit, use two-pass VBR.