How big will the video be, and how long will it take to send
Bitrate times duration is a file size; a file size is a waiting time on your line and a pass or fail against every app that has a limit. This calculator gives you all three before the upload starts.
The Video Size and Upload Time calculator estimates a video’s file size from its bitrate and duration, then shows how long it takes to upload at your connection speed. A 300 MB file on a 20 Mbit/s upload takes about two minutes.
Bits, bytes and the eight that separate them
Bitrate is measured in bits per second, file size in bytes, and there are eight bits in a byte. A 10 Mbps stream for 60 seconds is 600 megabits, which is 75 megabytes. That factor of eight is the whole reason a "100 Mbps" connection downloads a gigabyte in about eighty seconds rather than ten, and it is where most size estimates go wrong first.
The second correction is that networks never deliver their advertised number. Wi-Fi loses packets, the far end throttles, TLS adds a little overhead, and the last ten percent of a transfer crawls while the other side finishes writing. Counting on 85% of the line speed is optimistic enough to be useful and pessimistic enough to be honest.
The third is the container: an MP4 adds an index, timestamps and metadata around the streams, which is roughly two percent for a normal single-audio file. Small enough to ignore in conversation, large enough to break a limit that is enforced to the byte.
What one gigabyte costs on each connection
| Connection | 1 GB upload | 250 MB upload |
|---|---|---|
| 5 Mbps (poor 4G) | 33 min | 8 min |
| 10 Mbps (typical 4G) | 16 min | 4 min |
| 25 Mbps (home upload) | 6 min 40 s | 1 min 40 s |
| 50 Mbps (fibre) | 3 min 20 s | 50 s |
| 100 Mbps | 1 min 40 s | 25 s |
| 1 Gbps | 10 s | 3 s |
Three inputs, three answers
Bitrates and length
The video and audio bitrate your export uses, and the real duration of the file.
Read the size
Megabytes for the file, and megabytes per minute so you can scale it to the next cut.
Read the waiting time
Pick your upload speed and see the transfer time next to the limits of the apps you send through.
A limit is not a target
Every app below accepts a file up to a number, and almost every one of those numbers is smaller than people expect. Discord's free tier stops at 10 MB, which is a fifteen-second 1080p clip; WhatsApp's document limit is 16 MB, not the 64 MB that the app's own media sender uses. Email is stuck at 25 MB across almost every provider, because the limit belongs to the protocol, not to the mailbox.
The list in the tool checks your file against each of them and marks what fits. It is meant to be read before the export, not after: a two-minute video that lands at 12 MB is fine everywhere except three of those apps, and knowing that early is the difference between one export and three.
Limits move. Platforms raise them quietly and lower them during busy periods, and a paid tier changes the answer completely. Treat the list as the order of magnitude, and the app's own error message as the truth.
- check_circleDivide by eight before you compare bits to bytes
- check_circleAdd the audio stream to the video stream
- check_circleAssume 85% of the line, not the advertised number
- check_circleCheck the app's limit for the file type you are sending
- check_circleLeave headroom for the container
- check_circleSend a link instead of the file when it is over 100 MB
Questions about size and time
Why is my exported file bigger than the estimate?expand_more
Does the calculator know my real internet speed?expand_more
Is the upload time the same for YouTube as for a file host?expand_more
How do I make a video smaller without re-encoding it?expand_more
Why does 1 GB take so long on a 25 Mbps line?expand_more
Do these numbers work for audio files?expand_more
Know the size before the render
Two bitrates and a duration, and the export stops being a surprise.
fact_checkQuick facts
- Upload time is the file size divided by the upload speed: 300 MB at 20 Mbit/s takes two minutes, because 300 × 8 = 2,400 Mbit and 2,400 ÷ 20 = 120 seconds.
- The upload speed of an ADSL or cable line is usually a fraction of the download speed, which is why large files take longer than expected.
- H.264 is the codec that made HD video practical on the web: it is decoded by every current browser and phone without a plugin.menu_bookITU-T
- Lowering the bitrate of H.264 throws away detail in fast movement first, which is why sport and confetti are the hardest scenes to compress.menu_bookITU-T
- WebM was published as a royalty-free alternative to H.264 and uses VP8, VP9 or AV1 for the picture and Vorbis or Opus for the sound.menu_bookThe WebM Project
helpQuestions people ask
How long does it take to upload a 1 GB video?expand_more
Why are uploads slower than downloads?expand_more
How can I make a video smaller before uploading?expand_more
hubWhat this page is about
- H.264 / AVCopen_in_new
The video codec standardised by ITU-T as H.264 and by ISO/IEC as MPEG-4 AVC, decodeable by every current browser.
- WebMopen_in_new
A royalty-free container from the WebM Project for VP8, VP9 or AV1 video with Vorbis or Opus audio.
library_booksOfficial sources cited on this page
Keep going with the next tool
The tools in this group that do the next piece of the same work, all switched on right now.
Switched-off tools are not listed here: only what works right now.