Pick a length, resolution, codec, and audio bitrate to see the estimated file size. Or enter a size limit and get the video bitrate that fits.
Video length
Hours
Minutes
Seconds
Estimated file size
Breakdown
Transfer time at example speeds
TIP
To cut the size at similar quality, switch to H.265 or AV1. Check first that the devices and apps you are sending to can play them.
Resolution and quality
Codec
Audio bitrate
How to Calculate Video File Size
A video's file size is set mostly by two numbers: bitrate (data used per second) and length. Multiply them, add the audio, and you have the size. Two 10-minute videos at the same resolution can differ many times over in size if one is exported at a higher bitrate.
This calculator lets you choose a resolution preset, codec (H.264, H.265, or AV1), audio bitrate, and length, then shows the estimated size with a video and audio breakdown. You can also type your own video bitrate in kbps.
The second mode works backward. Enter the size you must stay under, such as a Discord, email, or messaging limit, and it returns the total bitrate and the video bitrate to export with.
Common Uses: Exports, Uploads, and Storage
Checking an export before you render
Compare resolution and bitrate combinations in your editor before you export, so you know roughly how big the file will be.
Fitting a chat or email size limit
Pick a target like Discord (free), WhatsApp, or email and get the video bitrate that keeps your clip under the cap.
Comparing H.264, H.265, and AV1
See how much smaller a file gets when the codec changes, using the efficiency factors listed in the notes below.
Planning storage for long recordings
Estimate the size of a lecture, stream archive, or screen recording that runs for hours before you pick a drive or cloud plan.
Steps to Estimate a Size or Find a Target Bitrate
- Set the video length with the hours, minutes, and seconds buttons, or tap a quick length such as 5 min.
- In Calculate size mode, pick a resolution and quality preset. To use your own number, type a video bitrate in kbps.
- Choose a codec and an audio bitrate. Select No audio for silent video.
- Read the estimated size, the video and audio breakdown, and the transfer times. To work from a limit instead, switch to Fit a size limit, pick a target or enter megabytes, and read the bitrate to export with.
Note: The calculation runs in your browser. The values you enter are not sent anywhere.
Accuracy and Limits of the Estimate
- Results are estimates from average bitrate. Variable bitrate, quality-based encoding (CRF), and container metadata can move the final file a few percent in either direction.
- Sizes use 1 MB = 1,000,000 bytes and 1 GB = 1,000 MB, plus 1.5% for container overhead. Some operating systems and apps show sizes in binary units, so the same file can look about 5% smaller there.
- The efficiency factors are H.265 at 55% and AV1 at 35% of the H.264 bitrate. They are rough planning values, and real results depend on the encoder and settings.
- Upload limits change. The values in the target list were current when this page was written, so confirm them with the service before you export.
File Size per Minute of Video: 480p to 4K
Size per minute of video with 128 kbps audio, using the same bitrates as the presets in the calculator. H.265 and AV1 columns apply the 55% and 35% factors to the video bitrate.
| Resolution / quality | H.264 bitrate | H.264 | H.265 | AV1 |
|---|---|---|---|---|
| 480p (SD) | 1 Mbps | 9 MB | 5 MB | 4 MB |
| 720p standard | 2.5 Mbps | 20 MB | 11 MB | 8 MB |
| 720p high | 4 Mbps | 31 MB | 18 MB | 12 MB |
| 1080p standard | 5 Mbps | 39 MB | 22 MB | 14 MB |
| 1080p high | 8 Mbps | 62 MB | 35 MB | 22 MB |
| 1440p (2K) | 16 Mbps | 123 MB | 68 MB | 44 MB |
| 4K standard | 35 Mbps | 267 MB | 148 MB | 94 MB |
| 4K high | 50 Mbps | 382 MB | 210 MB | 134 MB |
Values include 1.5% container overhead and are rounded. Use the calculator above for other lengths, audio settings, or custom bitrates.
Bitrate, Codecs, and Fitting a Size Limit
How the numbers behind the estimate work, and how to plan an export around a limit.
File size equals bitrate times length
Size in bytes = (video bitrate + audio bitrate) × seconds ÷ 8.
Resolution and frame rate affect how good the picture looks at a given bitrate, but the bitrate is what sets the size. At the same settings, halving the bitrate roughly halves the file.
H.265 and AV1 compared with H.264
H.265 (HEVC) and AV1 are designed to reach similar visual quality at a lower bitrate than H.264, which is why this tool applies 55% and 35% factors.
The trade-offs are compatibility and time. Older devices and some apps cannot play them, and they typically take longer to encode. If you are not sure who will watch the file, H.264 is the safe choice.
What audio adds to the total
Audio is small next to video but adds up over long recordings: 128 kbps is about 58 MB per hour, and 320 kbps is about 146 MB per hour.
For meetings, lectures, and screen recordings, 96 to 128 kbps is usually enough. Save higher audio bitrates for music or content where sound quality matters.
Working backward from a size limit
Divide the size you can use by the length to get the total bitrate, then subtract the audio bitrate to get the video bitrate.
For example, a 20 MB limit and a 60-second clip leave about 2,627 kbps in total. With 128 kbps audio, that is about 2.5 Mbps for the video. Fit a size limit mode does this math, including the overhead, for you.
Common Mistakes When Exporting for a Size Limit
Choosing a resolution and ignoring the bitrate
Picking 1080p or 4K in your editor without checking the bitrate can produce a file several times larger than you expected.
💡 See the solution▼
Landing a few megabytes over the limit
The file comes out at 21 MB for a 20 MB limit, and you have to export again. Variable bitrate makes this easy to do.
💡 See the solution▼
Using a codec the viewer cannot play
An H.265 or AV1 file saves space, but it may not open on an older phone, an older TV, or the app the viewer uses.
💡 See the solution▼
Leaving audio at 320 kbps on a long recording
High audio bitrates add roughly 88 MB per hour compared with 128 kbps, which matters when you are near a limit.
💡 See the solution▼
Video File Size and Bitrate FAQ
Q.How do you calculate video file size?
A. Add the video bitrate and the audio bitrate, multiply by the length in seconds, and divide by 8 to get bytes. For example, 5,000 kbps video plus 128 kbps audio for 60 seconds is about 38.5 MB. This calculator also adds 1.5% for container overhead, so it shows about 39 MB.
Q.Does a higher resolution make the file bigger?
A. Not by itself. At the same bitrate, 720p and 4K produce the same file size. But a higher resolution usually needs a higher bitrate to look good, so exports at higher resolutions tend to be larger. The resolution presets in this tool each use a typical H.264 bitrate, and you can type your own.
Q.How much smaller are H.265 and AV1 files than H.264?
A. This calculator assumes H.265 (HEVC) needs about 55% of the H.264 bitrate and AV1 about 35% for similar visual quality. These are planning figures, not guarantees. The real savings depend on the encoder, its settings, and how much motion is in the video.
Q.How do I get a video under Discord's upload limit?
A. Switch to Fit a size limit, choose a Discord option, and enter your video length. The tool shows the total bitrate and the video bitrate that fit. At the time of writing, Discord's free limit is 20 MB (raised from 10 MB in August 2026), Nitro Basic allows 50 MB, and Nitro allows 500 MB. Discord has changed these limits before, so check its help page before you rely on them.
Q.How do I make a video fit a 25 MB email limit?
A. Gmail caps attachments at 25 MB, but attachments grow by roughly a third when email encodes them, so a file of about 18 MB is a safer target. The Email attachment option in Fit a size limit uses 18 MB. For a 1-minute video with 128 kbps audio, that leaves about 2.2 Mbps for the video.
Q.What bitrate should I use for 1080p?
A. The presets here use 5 Mbps for standard 1080p and 8 Mbps for high-quality 1080p, both for H.264. They are starting points for estimating size, not requirements. Fast action, film grain, and screen recordings with lots of change can need more, and still scenes can look fine with less.
Q.How much does audio add to the file size?
A. At 128 kbps, audio adds about 58 MB per hour. At 320 kbps it adds about 146 MB per hour, roughly 88 MB more. For a long lecture or meeting recording where sound quality matters less, 96 to 128 kbps keeps the file smaller.
Q.Is anything I enter sent to a server?
A. No. The calculation runs in your browser, and the length, bitrate, and size values you enter are not uploaded or stored.
Q.Why is my exported file a different size than the estimate?
A. The estimate assumes the bitrate you set is the average over the whole video. Encoders using variable bitrate or quality-based modes (such as CRF) can land above or below that target, and containers add metadata. Expect a difference of a few percent, and more with quality-based encoding.
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