Video file size calculator by codec, bitrate and duration.
Pick a codec (ProRes, DNxHR, YouTube's recommended rates or your own bitrate), the resolution, the frame rate and the duration to see how much space the video takes. The calculator also finds the bitrate that fits a target size and adds up storage for a multi-camera shoot.
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How many copies you keep: 2 means the original plus one backup.
- File size
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- Per minute
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- Per hour
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Bitrates in decimal Mbps. Sizes in decimal GB and TB (1 GB = 1,000,000,000 bytes), as on cards, drives and macOS. Windows divides by 1,024 and shows smaller numbers under the same name.
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How to calculate video file size
- 01
Pick a codec or type a bitrate
ProRes and DNxHR carry the rates Apple and Avid publish for each resolution and frame rate; YouTube carries its recommended upload rates.
- 02
Set the audio and duration
Choose the audio (AAC or uncompressed PCM) and type the duration. The size shows per file, per minute and per hour.
- 03
Switch modes when you need to
Use bitrate for a size to fit a limit, or shoot storage to add up hours, cameras and backup copies.
How do I calculate video file size?
Multiply the bitrate by the duration in seconds and divide by 8, since bitrate is in bits and files are measured in bytes. An 8 Mbps video that runs 10 minutes is 8 x 600 ÷ 8 = 600 MB. Add the audio the same way: 384 kbps over 10 minutes adds 28.8 MB.
That is the size of the content. The container (MP4 or MOV) adds well under 1%. Delivery codecs like H.264 and H.265 vary their bitrate with the picture, so the real file can come out a little larger or smaller; ProRes stays close to its target rate, and DNxHR has a fixed size per frame.
| Bitrate | 1 minute | 1 hour |
|---|---|---|
| 8 Mbps (YouTube 1080p) | 60 MB | 3.6 GB |
| 45 Mbps (YouTube 4K, top of range) | 338 MB | 20.3 GB |
| 147 Mbps (ProRes 422, 1080p 29.97) | 1.1 GB | 66.2 GB |
| 884 Mbps (ProRes 422 HQ, 4K UHD 29.97) | 6.6 GB | 398 GB |
How much space does an hour of ProRes or DNxHR take?
Both are editing codecs: big files that are light for your computer to cut. The calculator's rates come from the Apple ProRes white paper (its target data rate table) and the DNxHR bandwidth table Avid publishes. At 1920 x 1080 and 29.97 fps, ProRes 422 runs 147 Mbps and 422 HQ runs 220 Mbps; DNxHR HQ runs about 218 Mbps.
At 4K UHD (3840 x 2160) and 29.97 fps, ProRes 422 HQ reaches 884 Mbps, close to 400 GB per hour. Doubling the frame rate doubles the size. That is what proxies are for: ProRes 422 Proxy and DNxHR LB take a fraction of the space, and you edit with them and relink to the originals for export.
DNxHR HQ and HQX are the same size; the difference is bit depth (HQX is 12-bit). The ProRes 4444 and 4444 XQ figures are without an alpha channel.
What bitrate do I need to hit a target file size?
Run the math backwards: size in bits divided by duration in seconds. For a 10 minute video to fit in 100 MB, the total is 800,000,000 bits ÷ 600 s = 1.33 Mbps. Take out the audio (128 kbps, say) and about 1.2 Mbps is left for video. The bitrate for a size mode does this for you and leaves 2% headroom for the container and for encoders that overshoot.
For YouTube uploads, use YouTube's recommended rates: 8 Mbps at 1080p and 35 to 45 Mbps at 4K for 24, 25 or 30 fps; at 48, 50 or 60 fps, 12 Mbps and 53 to 68 Mbps. The recommended audio is AAC or Opus at 384 kbps stereo. H.265 usually reaches the same quality as H.264 at a lower bitrate.
How much storage do I need for a multi-camera shoot?
Multiply the size per hour by the hours each camera records, by the number of cameras and by the number of copies. An event with 3 cameras recording 2 hours each in ProRes 422 HQ 4K at 25 fps, with 24-bit PCM audio, takes about 2 TB; with one backup, 4 TB. The shoot storage mode shows the total, per camera and without copies.
The same mode tells you how long a card or drive lasts: a 256 GB card at 100 Mbps records about 5 hours and 41 minutes. The capacity printed on a card is decimal, and a little less is left after formatting.
About units: cards, drives and macOS count 1 GB as 1,000,000,000 bytes. Windows divides by 1,024 and shows the result under the same name, which is why a 1 TB drive appears as about 931 GB. The calculator shows both numbers so nothing catches you off guard.
More than a file size calculator. Hours of footage become what matters.
Frequently asked questions
How big is an hour of 4K video?
It depends on the codec. At YouTube's recommended bitrate (35 to 45 Mbps), an hour of 4K is 16 to 20 GB. In ProRes 422 HQ 4K at 29.97 fps (884 Mbps), it goes past 390 GB. Pick the codec and resolution in the calculator to see the exact number.
How do I convert Mbps to MB per second?
Divide by 8. 100 Mbps is 12.5 MB per second, or 750 MB per minute. Mbps means megabits, the unit for bitrate; MB means megabytes, the unit for file size.
Why does Windows show a smaller size?
Because Windows counts 1 GB as 1,073,741,824 bytes (1,024 x 1,024 x 1,024) while manufacturers count 1,000,000,000. The file is the same; only the ruler changes. The calculator shows both: decimal GB and the binary value (GiB) that Windows displays.
How many minutes of video fit on a 128 GB card?
Divide the capacity by the bitrate. At 100 Mbps, a 128 GB card records about 2 hours and 50 minutes; at 200 Mbps, half that. In shoot storage mode, pick the card and see the time for your camera's bitrate.
Where do the ProRes, DNxHR and YouTube rates come from?
From the Apple ProRes white paper (target data rate table), the DNxHR bandwidth table published by Avid and YouTube's recommended upload encoding settings page. They are the makers' references; real files can vary a little with the picture.
Is the calculator free?
Yes. It is free, with no sign-up and no usage limit.
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