File size = bitrate × duration ÷ 8 — solve any one of bitrate, length or size, add audio, copy in one click — browser-only
- Runs locally
- Category Calculator
- Best for Checking file type, size, metadata, and obvious mismatch signals before sharing.
What this tool does
Free video bitrate and file size calculator for editors, streamers and anyone who exports footage. Three numbers are locked together by one formula: file size (MB) equals total bitrate (Mbps) times duration (seconds) divided by 8. Give the tool any two and it solves the third. Pick a target size and a clip length, and it tells you the bitrate to set in your encoder. Set a bitrate and a length, and it predicts the export size before you wait twenty minutes for the render. Set a size and a bitrate, and it tells you how many minutes fit on the card or under an upload cap. Video and audio bitrate are entered separately and summed, so a 8 Mbps 1080p stream plus 192 kbps AAC is handled correctly. Presets for YouTube 1080p, 4K, Instagram and a tight Discord upload get you close in one tap. Everything runs in your browser, with one-click copy and a shareable link. 100% client-side, nothing uploaded.
Tool details
- Input
- Numbers
- The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
- Output
- Live result + Copy
- The result area focuses on usable output, with copy, download, or preview actions when supported.
- Privacy
- Browser-side processing
- The main tool logic does not call an external API, so inputs normally stay in the current tab.
- Save / share
- Shareable URL state
- Key settings are encoded in the URL so another person can reopen the same setup.
- Performance budget
- Initial JS <= 9 KB
- No WASM budget is declared, keeping the tool quick to open on mobile.
- Best fit
- Calculator · Content Creator
- Category and role tags drive related tools, internal links, and quick fit checks.
How to use
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1. Input
Paste or drop your content into the tool panel.
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2. Process
Click the button. All processing is local in your browser.
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3. Copy / Download
Copy the result or download to disk in one click.
How Video Bitrate Calculator fits into your work
Use it before upload, handoff, archive, support review, or any moment where a file needs one local check before it leaves your machine.
File jobs
- Checking file type, size, metadata, and obvious mismatch signals before sharing.
- Preparing mixed folders for upload, archive, intake, or review.
- Keeping sensitive files in the browser instead of sending them to an account-based service.
File checks
- Do not treat the extension alone as proof of the real file type.
- Review metadata before a file goes to customers, vendors, or a public page.
- Keep the original file until the copied, converted, or exported result is verified.
Good next steps
These links move the current task into a more complete workflow.
- 1 Aspect Ratio Calculator Calculate aspect ratio — fix any 1 of [width, height, ratio], get the other two. Open
- 2 Data Storage Converter Convert bytes, KB, MB, GB, TB and bits — decimal (1000) and binary (1024, KiB/MiB/GiB) side by side, with the hard-drive 931 GiB gotcha explained — browser-only Open
- 3 Unit Converter Convert between length, weight, temperature, area, volume, speed, time — instant, browser-only Open
Real-world use cases
Hit a hard upload size cap
A platform caps uploads at 25 MB and your clip is 40 seconds. Switch the mode to solve for bitrate, type 25 MB and 40 seconds, and the tool returns the exact total bitrate to set in your encoder. Subtract your audio and you have the video bitrate. Now the export lands under the cap on the first try instead of after three re-encodes.
Predict the export size before rendering
A 10-minute screencast at 8 Mbps video plus 160 kbps audio is a long render to find out it is too big. Enter the bitrates and the duration and read the predicted size before you start. If 612 MB is too much for the client share, drop the bitrate and watch the number fall in real time, then commit to the export you actually want.
Plan how long a recording card will hold
A camera writes a 50 Mbps codec to a 64 GB card. Solve for duration: enter 64000 MB and 50 Mbps and the tool tells you the card holds about 170 minutes. Now you know whether one card covers the shoot or you need a spare in your pocket before you leave for the location.
Match YouTube and platform recommended bitrates
You are exporting for YouTube but unsure between 1080p and 4K settings. Tap the 1080p preset (8 Mbps) or the 4K preset (45 Mbps), set your real clip length, and compare the predicted file sizes side by side. The preset seeds the recommended number so you start from a known-good value rather than a guess.
Common pitfalls
Forgetting the divide-by-8. Multiplying 8 Mbps by 60 seconds and reading 480 MB confuses bits with bytes. The right answer is 60 MB because 8 bits make 1 byte. The tool always divides by 8 for you, so the size it shows is already in megabytes.
Leaving audio out of the budget. On a short clip 128 kbps audio is negligible, but over an hour it is roughly 56 MB that quietly pushes you past an upload cap. Enter the audio bitrate in its own field so the total reflects both streams.
Mixing kbps and Mbps. Typing 8000 in the Mbps field instead of 8, or 192 in a Mbps field that wanted kbps, throws the result off by a thousand. The tool labels each field with its unit — Mbps for video, kbps for audio — so check the label before you trust the number.
Privacy
Every calculation here — the bitrate formula, the audio sum, the unit conversions and the presets — is plain JavaScript running in your browser tab. No clip name, bitrate or size ever leaves the page, and nothing you type is logged. The one caveat: the shareable link encodes your numbers and mode in the query string, so a link pasted into chat records those values in the recipient server's access log. For a confidential project budget, use the copy button and paste the text instead of sharing the URL.
FAQ
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