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Video file size estimator
Estimate how big a video file will be from its length and bitrate, and check it against the upload limit.
Your film
Not sure of the bitrate? Common export settings are listed in your editor's export panel. Use the number it shows, or start with the defaults and export a short test.
Your estimate
A video file is about its length times its bitrate. Multiply the total bitrate in megabits per second by the length in seconds, then divide by eight to get megabytes. A 60 second film at 8 megabits per second is about 60 megabytes.
A video file is big because of two numbers: how long it is, and how many bits it uses every second. That second number is the bitrate. A short film at a low bitrate is small. The same film at a high bitrate can be many times bigger, even though it plays for the same time.
This estimator does the sum for you. Enter the length of the film, the bitrate you export at, and the audio bitrate. It adds them, multiplies by the length and converts the result from megabits to megabytes. Then it checks the answer against an upload limit you choose, so you know before you send.
How the size is worked out
Bitrate is measured in megabits per second. A file's size in megabits is its total bitrate times its length in seconds. Most people think in megabytes, and there are eight megabits in a megabyte, so the last step divides by eight. The formula is simple: size in megabytes equals video bitrate plus audio bitrate, times seconds, divided by eight.
This is an estimate. Containers add a little overhead, and a video that changes a lot, such as fast cuts or lots of movement, usually needs a higher bitrate to look right. Use the number to plan, then check the real file size in your editor after export. Keep a note of the bitrate you used, so you can match it next time.
Why the upload limit matters
Files that are too big to send by email, or too big for a form, cause delays. Many email services refuse large attachments, and a file that is over a limit has to be shared another way. Before you send a film to a client or upload it to a brief, check its size against the limit that applies. The Overnight Cut brief form accepts files up to 50 MB each, so a film under that size goes through directly. Larger files can be shared as a link to a cloud drive instead.
What to change if the file is too big
Lowering the video bitrate is the biggest change, and it usually costs the least visible quality. Lowering the resolution also reduces the size, and so does cutting unused seconds at the start or end. Lower the audio bitrate only a little, because speech stays clear at modest rates. Export a test first, watch it on a phone, and only then decide how far to go.
If you are planning a film, the video cost calculator helps you compare the cost of making it yourself with having it made. The voiceover length checker helps you fit the narration to the length of the film before you record it. For the wider picture, read video aspect ratios for product launches.
undefinedHow to use it
- Enter the length. Type the length of the finished film in seconds. A 1 minute 30 second film is 90 seconds.
- Enter the video bitrate. Use the bitrate from your export settings, in megabits per second. Leave the default if you are not sure, then export a test.
- Enter the audio bitrate. Type the audio bitrate in kilobits per second. 128 is a common value for speech and music.
- Check against the limit. Read the estimate in megabytes and whether it fits the limit you chose. If it does not, lower the bitrate or cut seconds, then check again.
Frequently asked questions
How do I work out the file size of a video?
Add the video bitrate and the audio bitrate in megabits per second, multiply by the length in seconds, then divide by eight. The result is in megabytes. The estimator does this for you as you type, so you can try different bitrates.
What bitrate should I export at?
It depends on how much detail the film has and how much size you can accept. Fast cuts and lots of movement need more bitrate than a calm film. Export a short test, watch it on the device your viewers will use, and choose the lowest bitrate that still looks right to you.
Why is my real file bigger than the estimate?
The estimate uses the bitrate you enter as a steady rate. The container format adds some overhead, and many encoders vary the bitrate from scene to scene. Use the estimate for planning, then read the real size from the exported file.
What is the upload limit for our films?
The Overnight Cut brief form accepts up to 50 MB for each file. A larger film can be shared as a link to a cloud drive. The studio will tell you how to send it when that happens.
Is anything I enter sent anywhere?
No. The calculation runs in your browser, and nothing you type is sent to us. The result is only on your screen until you copy it or close the page.
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