Quick answer: Bitrate is the amount of data used per second of video or audio, and together with the duration it decides how big the file is.
Bitrate explained
Bitrate is how much data a video or audio file uses for each second of playback. It is measured in bits per second, usually Mbps (megabits per second) for video and kbps for audio. A higher bitrate generally means more detail and a bigger file.
You can estimate file size from it: size equals bitrate times duration. A 10 Mbps video lasting 60 seconds holds 600 megabits, which is 75 megabytes.
To make a video smaller for sending, lowering the bitrate is the main lever. A modest reduction is often hard to see, while a large one causes blocky, blurry images, especially in fast motion.
Bitrate to file size: a quick table
The rule is: megabytes per minute = Mbps × 60 ÷ 8. For example, 20 Mbps × 60 = 1,200 megabits, and 1,200 ÷ 8 = 150 MB per minute.
| Bitrate | Per minute | Per hour |
|---|---|---|
| 5 Mbps | 37.5 MB | 2.25 GB |
| 10 Mbps | 75 MB | 4.5 GB |
| 20 Mbps | 150 MB | 9 GB |
| 50 Mbps | 375 MB | 22.5 GB |
| 100 Mbps | 750 MB | 45 GB |
Audio works the same way. An MP3 at 128 kbps uses 128 × 60 ÷ 8 = 960 kB, just under 1 MB per minute; at 320 kbps it is 2.4 MB per minute.
Constant and variable bitrate
Constant bitrate (CBR) uses the same amount of data every second, so the file size is very predictable. Variable bitrate (VBR) spends more data on busy scenes and less on still ones, which usually gives better quality for the same overall size.
Phones and most video exports use variable bitrate. That is why two clips of the same length from the same phone can be quite different sizes: a windy beach needs more data than a person talking against a plain wall.
How to make a video smaller
- Trim it. Cutting unwanted parts reduces size with no quality loss in what remains.
- Lower the bitrate a moderate amount, then check the result on a big screen.
- Lower the resolution, for example 4K to 1080p, if the video will be watched on phones or laptops.
- Or skip compressing and send the original with a download link, up to 20 GB.
Frequently asked questions
What is a good bitrate for 1080p video?
It depends on the codec and the content, but H.264 at 1080p often looks good at around 8 to 12 Mbps. Fast action needs more.
Does a higher bitrate always mean better quality?
Up to a point. Beyond a certain level, extra bitrate adds size without visible improvement.
How do I find out a video's bitrate?
Divide the file size by the length, or check the codec information in VLC or MediaInfo. The video bitrate calculator does the arithmetic for you.
Is bitrate the same as resolution?
No. Resolution is how many pixels each frame has, while bitrate is how much data is spent per second. A low-bitrate 4K video can look worse than a high-bitrate 1080p one.
Ready to send?
Drop your files, get a link, done. Free up to 20 GB — no account needed.
Send files free