In this article
After reading, you'll understand:
- What bitrate is and how it's measured
- How bitrate relates to resolution and codec
- Recommended target bitrates, and how to estimate file size
- CBR vs VBR, and how adaptive streaming uses bitrate
What is bitrate?
Bitrate is the amount of data used to represent one second of video, measured in bits per second — usually kilobits (kbps) or megabits (Mbps). A higher bitrate means more data spent per second, which generally means more detail and a larger file; a lower bitrate means a smaller file that can look soft or blocky if pushed too far.
It is the core lever behind streaming quality. Two videos at the same resolution can look completely different depending on bitrate: a 1080p clip starved of bitrate will show compression artifacts, while the same clip at a healthy bitrate looks crisp. The codec matters too — modern codecs achieve the same quality at a lower bitrate.
Recommended bitrate by resolution
Industry-standard target bitrates for H.264 (AVC) encoding. H.265 and AV1 achieve similar quality at roughly half these values.
| Resolution | Name | Min bitrate | Recommended |
|---|---|---|---|
| 360p | SD | 300 kbps | 500–800 kbps |
| 480p | SD | 600 kbps | 1–1.5 Mbps |
| 720p | HD | 1.5 Mbps | 2.5–4 Mbps |
| 1080p | Full HD | 3 Mbps | 5–8 Mbps |
| 2160p | 4K | 10 Mbps | 15–25 Mbps |
Highlighted rows are the sweet spot for most audiences.
Bitrate and file size
Bitrate is also what determines how much a video weighs — and therefore what it costs to store and deliver. The rule of thumb is simple:
Rough estimate
File size ≈ bitrate × duration ÷ 8. A 10-minute (600 s) video at 5 Mbps is about 5 × 600 = 3,000 megabits — divide by 8 to get bytes, so roughly 375 MB. Variable bitrate and the audio track shift the real figure, but it's how you sanity-check storage and bandwidth before you commit.
This is also why adaptive streaming saves money at scale: a viewer on a slow connection is served a lower-bitrate rendition, so they pull far less data than a viewer getting full 1080p — and the delivery bill follows the bits actually sent.
CBR vs. VBR, and adaptive streaming
Constant Bitrate (CBR) holds the same data rate across the whole video — predictable, but it wastes data on simple scenes and can starve complex ones. Variable Bitrate (VBR) spends more on complex scenes and less on simple ones, giving better quality per megabyte.
Adaptive bitrate streaming adds another layer: the video is encoded at several bitrates (a rendition ladder), and the player switches between whole renditions in real time to match each viewer's bandwidth — preventing buffering on slow connections while serving maximum quality on fast ones.
How Kinescope handles this
You never set a bitrate on Kinescope. Transcoding builds a full ladder of resolution-and-bitrate renditions from your source automatically, and the adaptive player serves each viewer the right one over the CDN. Upload once; every viewer gets an appropriate bitrate for their connection, and you pay for the bits actually delivered.
Read the Kinescope docsFrequently asked questions
What is a good bitrate for 1080p video?
For H.264 at 1080p, a recommended target is roughly 5–8 Mbps (with a minimum around 3 Mbps). 720p sits around 2.5–4 Mbps, 480p around 1–1.5 Mbps, and 4K around 15–25 Mbps. H.265 and AV1 reach similar quality at roughly half these values.
Is higher bitrate always better?
Up to a point. Higher bitrate means more detail and a larger file, but beyond a certain level the eye stops noticing while the file and bandwidth cost keep rising. The goal is the lowest bitrate that still looks great for a given resolution and codec — which is exactly what a well-built rendition ladder targets.
What is the difference between bitrate and resolution?
Resolution is the pixel dimensions of the frame (720p, 1080p, 4K); bitrate is how much data is spent per second describing those pixels. A 1080p video at too low a bitrate looks blocky despite its resolution — both need to match for a sharp result.
What is CBR vs VBR?
Constant Bitrate (CBR) spends the same data rate throughout, which is predictable but wasteful on simple scenes. Variable Bitrate (VBR) spends more on complex scenes and less on simple ones, giving better quality per megabyte. Adaptive streaming layers on top: the player also switches between whole renditions based on bandwidth.
How do I estimate video file size from bitrate?
Multiply the bitrate by the duration. A 10-minute (600-second) video at 5 Mbps is about 5 × 600 = 3,000 megabits, or roughly 375 MB (divide by 8 to convert bits to bytes). It is a rough figure — variable bitrate and audio shift it — but it is how you sanity-check storage and bandwidth costs.
Do I need to set a bitrate on Kinescope?
No. Kinescope transcodes each upload into a full ladder of resolution-and-bitrate renditions automatically, so every viewer gets an appropriate bitrate for their connection. There are no encoding settings for you to tune.
Further reading
- Bit rate — Wikipedia — a vendor-neutral overview.
