How the calculator works
Size = (video bitrate + audio bitrate) × duration ÷ 8. The tool uses decimal units like file explorers on Mac and most upload forms: 1 MB is 1,000,000 bytes. When you look for a bitrate to fit a limit, it keeps a 5% safety margin for variable bitrate and container overhead.
- Choose whether you want the file size or the bitrate for a limit.
- Enter the length of the video.
- Enter the video bitrate, or the size limit you need to respect.
- Pick the audio bitrate. 192 kbps is a good default for voice and music.
Recommended upload bitrates for YouTube
| Resolution | 24 to 30 fps | 48 to 60 fps |
|---|---|---|
| 720p | 5 Mbps | 7.5 Mbps |
| 1080p | 8 Mbps | 12 Mbps |
| 1440p (2K) | 16 Mbps | 24 Mbps |
| 2160p (4K) | 35 to 45 Mbps | 53 to 68 Mbps |
These are YouTube’s recommended bitrates for standard dynamic range uploads. TikTok and Instagram re-encode heavily, so 1080p at 8 to 12 Mbps is plenty for them.
Common size limits
- Discord: 10 MB per file without Nitro.
- Gmail and most email: 25 MB per message, including the other attachments.
- WhatsApp: about 2 GB per file in recent versions, but sent videos are usually compressed.
Need the right frame size too? See the aspect ratio calculator.
Last reviewed October 2026.
Frequently asked questions
How do you calculate video file size?
File size equals total bitrate multiplied by duration, divided by 8 to turn bits into bytes. A 10-minute video at 8 Mbps video plus 192 kbps audio is about 8.2 Mbps × 600 s ÷ 8 ≈ 615 MB.
What bitrate should I use for YouTube?
YouTube recommends about 8 Mbps for 1080p at 24 to 30 fps, 12 Mbps at 60 fps, and 35 to 45 Mbps for 4K at 30 fps. Higher bitrates give YouTube a better source to re-encode from.
How do I get a video under a size limit?
Choose “Bitrate for a size limit”, enter the limit and the video length. The calculator gives the maximum total bitrate and the video bitrate to set in your editor or encoder after reserving room for the audio.
Why is my exported file a different size?
Encoders using variable bitrate (VBR) aim for an average and can land a few percent above or below. Containers like MP4 also add a little overhead. Keep a 5% margin when you need to stay under a strict limit.
What is the difference between Mbps and MB/s?
Mbps is megabits per second, the unit used for bitrates. MB/s is megabytes per second. One byte is 8 bits, so 8 Mbps equals 1 MB/s.
Is anything uploaded?
No. It is a calculator: you type numbers and the result appears in your browser.