Free Video Bitrate Calculator — File Size & Bitrate
Every upload limit is really a bitrate question. This calculator converts both ways: tell it your video length and a target file size (a 25 MB email limit, a 16 MB WhatsApp cap) and get the exact video bitrate to type into your editor — or enter the bitrate you plan to export at and see the final file size before you wait for a render. Pure math, done instantly in your browser.
Video Bitrate Calculator
Convert between file size and bitrate before you export — hit your upload limit the first time, every time.
1 Your video
2 Bitrate & size results
🎬 Your numbers
How it works
File size is simply bitrate multiplied by time. The tool takes your duration, subtracts the audio bitrate you choose from the total, and solves for the video bitrate (or works backwards from bitrate to megabytes). Sizes use the decimal megabytes that upload limits and editors use, so the number you see matches the number your platform enforces.
Everyday uses
- YouTubers — check an export’s expected size before a long render.
- Email & messaging — fit clips under 25 MB email or 16 MB WhatsApp limits without trial and error.
- Course creators — keep lesson files under your LMS upload cap.
- Discord & social posters — hit free-tier file limits on the first try.
Frequently asked questions
Should I use constant or variable bitrate?
Two-pass variable bitrate (VBR) gives better quality at the same average size; use the calculator’s number as the average/target bitrate.
Why is my real file slightly bigger than the estimate?
Containers add a little overhead (usually under 2%) and VBR can drift. Aim 5% under a hard limit to be safe.
What bitrate is good for 1080p?
Around 8–12 Mbps for YouTube uploads, 5–8 Mbps for general sharing. 4K needs roughly 35–45 Mbps.