Video File Size Calculator
Size from bitrate and length, with the bits-versus-bytes trap avoided.
- Free
- No signup
- Nothing uploaded
- No watermark
File size
384.6 MB
366.8 MiB
In gigabytes
0.38 GB
Bitrate for your target
1205 kbps
video only
How to Use the Video File Size Calculator Online
Give it the length in minutes and the video and audio bitrates in kilobits per second, and it returns the file size in megabytes, mebibytes and gigabytes. The trap is units: bitrate is in bits, size is in bytes, and the difference is a factor of eight. A back-of-envelope estimate that skips the division comes out eight times too large and still looks believable.
Size from bitrate and length, avoiding the bits-versus-bytes trap. Bitrate is quoted in megabits per second and file size in megabytes, a factor of eight — which is why a naive estimate comes out eight times too large and looks plausible enough to believe.
No software to install Free Works on any device
Step-by-Step Guide to Using the Video File Size Calculator
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1. Fill in your own figures or text
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2. The result updates as you type — there is no button to press
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3. The note underneath says what the number means and where the usual version of it is wrong
What is the Video File Size Calculator?
Size from bitrate and length, avoiding the bits-versus-bytes trap. Bitrate is quoted in megabits per second and file size in megabytes, a factor of eight — which is why a naive estimate comes out eight times too large and looks plausible enough to believe.
At a glance
- Inputs: Length in minutes, video bitrate in kbps, audio bitrate in kbps
- Output: Size in MB, MiB and GB
- Formula: (video + audio kbps) × 1,000 × seconds ÷ 8 = bytes
- Units: MB is 1,000,000 bytes; MiB is 1,048,576, which is what some operating systems show
- Runs: Plain arithmetic on the page; there is no file involved
- Price: Free, no signup
Why Use Video Tools in Your Browser?
Phone videos are large, and every app has its own rules for length, shape and format. Trimming, compressing, converting and resizing clips here gets them ready to post or send without uploading your footage to a stranger’s server.
“A shorter, smaller clip is far more likely to get watched.”
- Clips that fit upload limits
- GIFs from short moments
- Subtitles converted and shifted
- Screen recordings without software
- Vertical videos for Reels
- Sound pulled out as MP3
- Only the scenes you want
- Footage kept on your device
Popular Uses for Video Converters
These are the video jobs people come back for again and again.
- Reels and Shorts Crop a landscape clip into a vertical video for Instagram Reels or YouTube Shorts.
- WhatsApp status Cut a long video into short parts that fit a WhatsApp status.
- Email and chat limits Compress an MP4 so it can be sent without a file-too-large error.
- Reaction GIFs Turn a funny moment from a clip into a GIF to share in chats.
- Audio from video Save the soundtrack or speech from a video as an MP3 file.
- Tutorial recordings Record your screen to show a colleague how to do a task.
- Subtitle fixes Convert SRT to VTT or shift subtitle timing when words arrive too early.
- Playback problems Convert MOV, MKV or AVI files to MP4 so they play on any phone or TV.
What You Can Do with the Video File Size Calculator
Understands MP4 structure rather than treating the file as bytes
The calculation happens on your own machine, at your machine's speed
Trimming copies the existing stream where it can instead of re-encoding the whole file
Shows the resulting duration and size before the export starts
Why Use ToolXkit for Video File Size Calculator?
Your files stay with you
Everything runs inside your browser. Nothing you open or type is uploaded to a server.
Free, with no catch
No signup, no watermark and no daily limit on how often you use it.
Fast
Results appear in seconds, because nothing has to travel over the internet and back.
Works on any device
Use it on a computer, tablet or phone, in Chrome, Edge, Firefox or Safari.
Nothing to install
No app, no extension and no desktop program. Open the page and start.
Made for real people
Plain words and clear buttons, built by one developer who wanted tools like this to exist.
Clip Tools for Different Users
Content creators
Trim, crop and resize clips for each platform without a desktop editor.
Teachers and trainers
Record lessons on screen and cut videos down to the useful part.
Small businesses
Make short product videos and GIFs for shop pages and status updates.
Students
Shrink project videos to meet the upload limit of a college portal.
Support teams
Record bugs and walkthroughs, then compress them for tickets and emails.
Families
Share wedding and birthday clips that open on everyone’s phone.
Best Times to Trim or Compress a Video
Video tools are most useful when you are:
- Posting a Reel or Short
- Sending a clip over email
- Playing a file your TV rejects
- Making a GIF for a chat
- Recording a how-to for a colleague
- Adding subtitles to a lesson
- Saving only the best moments
- Pulling music out of a clip
Tips and Good to Know
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Container overhead and variable bitrate are not modelled, so real files land a little above or below.
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For a file you already have, look at its properties; this is for planning an encode or a recording that has not happened yet.
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To go the other way and find the bitrate that fits a size cap, use Video Bitrate Calculator.
Frequently Asked Questions
Answers to common questions about this tool.
Do I need to install anything to use the Video File Size Calculator?
No. Video File Size Calculator runs entirely in your browser — there is nothing to download, no extension and no desktop program. It works the same on Windows, macOS, Linux, Android and iPhone.
Is it safe to use the Video File Size Calculator online?
Safer than the usual alternative, yes. Most online tools upload your file to a server you know nothing about, where it sits until someone deletes it. Here the file never leaves your device — the processing happens in the page itself, so there is no server copy to leak, retain or sell.
Is there a limit on video length or size?
The site sets no limit. Video processing happens on your own device, so long or high-resolution clips need more memory and time. Short phone clips are quick, while hour-long 4K files are better handled on a computer.
Why is Video File Size Calculator slower than a desktop editor?
Video work is heavy, and here it runs inside a browser tab using your device’s own processor. That keeps the footage private, but it can take longer than installed software. Keep the tab open until it finishes.
Will the quality drop after compression?
Some detail is lost when a video is made much smaller. Moderate compression is hard to notice on a phone screen, while very small targets make fast motion look blocky. Try a setting and watch the result before sharing.
Can I turn a landscape clip into a vertical Reel?
Yes. Reels & Shorts Maker and Resize & Crop Video crop a wide clip to the tall 9:16 shape that Reels, Shorts and status updates use. Download the vertical version and it is ready to post.
Further reading
- Web video codec guide (MDN) How video codecs like H.264, VP9 and AV1 work and which browsers support them.
- Video file format (Wikipedia) Why MP4, MKV, MOV and WebM are containers, and what that means for playback.
- Subtitles (Wikipedia) How subtitles are timed and stored, including the SRT and WebVTT formats.
More Video Tools
Other free tools for the same kind of job.
- Compress Video Shrink a clip to get it under a size limit. Open tool
- Trim Video Cut a clip with handles you drag and a timecode you can type. Open tool
- Video Converter Convert between MP4, WebM and MOV. Open tool
- Video to MP3 Pull the soundtrack out of a video file. Open tool
- AVI to MP4 Convert old AVI video to MP4. Open tool
- Change Video Speed Make a clip slow motion, or speed it up. Open tool
- Compress AVI Shrink AVI video files. Open tool
- Compress MKV Shrink MKV video files. Open tool
- Compress MOV Shrink a QuickTime .mov video. Open tool