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Video Bitrate Calculator
Use this free video bitrate calculator to work out the link between bitrate, file size, and duration for any video. Find the bitrate you need from a target file size and length, check how big a file will be at a given bitrate, or see how long a video you can fit into a size limit. It includes an audio bitrate add-on and one-click presets for 480p, 720p, 1080p, and 4K.
Sizes use 1 GB = 1,024 MB and 1 MB = 1,024 KB. Bitrates use 1 Mbps = 1,000 Kbps. The audio bitrate is added to the video bitrate for total file size.
How it works
Video size, bitrate, and duration are tied together by one simple relationship: the file size is the total bitrate multiplied by the duration. Bitrate is the amount of data used per second, usually measured in megabits per second (Mbps). Multiply that by the number of seconds and you get the total number of megabits, and dividing by 8 turns megabits into megabytes, because there are 8 bits in every byte. Knowing any two of the three numbers lets you find the third, which is why this calculator has three modes.
Watch the units, because they are where most mistakes happen. Bitrates use decimal steps: 1 Mbps is 1,000 Kbps, and 1 Gbps is 1,000 Mbps. File sizes on computers traditionally use binary steps: 1 GB is 1,024 MB, and 1 MB is 1,024 KB. This calculator follows that convention and says so on the tool, because it matches how operating systems and most editing software report file sizes. A 1 GB file is therefore 1,024 MB, or 8,192 megabits, and a 10-minute video of that size needs about 13.65 Mbps.
The audio track is easy to forget and it always counts. The total bitrate of a file is the video bitrate plus the audio bitrate, so a video encoded at 8 Mbps with a 128 kbps audio track actually uses 8.128 Mbps in total. Over an hour that audio adds about 58 MB, and over a two-hour film it adds about 115 MB. This calculator lets you add an audio bitrate from 96 to 320 kbps, and it shows the video-only and total figures separately so you can see exactly what the audio costs.
Presets give you a starting point, not a rule. The 480p, 720p, 1080p, and 4K buttons set common streaming bitrates — 2.5, 5, 8, and 45 Mbps — but the right bitrate depends on what is in the frame. A still slide show or a talking head compresses far better than a football match or falling confetti, because the encoder only has to store what changes between frames. Busy, detailed motion needs a higher bitrate for the same quality, which is why variable bitrate encoding exists: it spends more data on hard scenes and less on easy ones, so the average bitrate matters more than the peak.
Bitrate (Mbps) = file size (MB) × 8 ÷ duration (seconds)
Duration (seconds) = file size (MB) × 8 ÷ total bitrate (Mbps)
Recommended bitrates
| Resolution | 30 fps streaming | 30 fps high quality | 60 fps |
|---|---|---|---|
| 480p | 1–2.5 Mbps | 2.5–4 Mbps | 3–5 Mbps |
| 720p | 3–5 Mbps | 5–8 Mbps | 6–10 Mbps |
| 1080p | 5–8 Mbps | 12–20 Mbps | 12–18 Mbps |
| 1440p | 12–16 Mbps | 18–25 Mbps | 20–30 Mbps |
| 4K | 35–45 Mbps | 45–80 Mbps | 60–100 Mbps |
Worked example
You have a 1 GB video file that is 10 minutes long, with a 128 kbps audio track. What bitrate was it encoded at?
Step 1: Convert the size to megabits. 1 GB is 1,024 MB, and each megabyte is 8 megabits, so 1,024 × 8 = 8,192 megabits.
Step 2: Convert the duration to seconds. 10 minutes × 60 = 600 seconds.
Step 3: Divide the total data by the time. 8,192 ÷ 600 = 13.65 Mbps total bitrate.
Step 4: Subtract the audio. 13.65 Mbps − 0.128 Mbps = 13.53 Mbps of video bitrate.
So the video was encoded at about 13.53 Mbps of video plus 128 kbps of audio. Select "Bitrate", enter 1 GB and 10 minutes, leave the audio at 128 kbps, and the calculator gives exactly that: 13.65 Mbps total, 13.53 Mbps video.
Choosing a bitrate for your own videos
Start from where the video will be watched. A video streamed over a mobile connection needs a lower bitrate than the same video played from a hard drive, because the viewer's connection is the limit. Most streaming platforms publish their own recommended bitrates, and they are a good guide even if you are not uploading to them. For a local archive or a master copy you plan to edit later, use a higher bitrate: storage is cheap and re-encoding a low-quality file later can never bring the detail back.
Frame rate matters too. A 60 frames-per-second video shows twice as many pictures as a 30 frames-per-second one, so it needs roughly 50 percent more bitrate to look equally clean. Resolution matters even more: doubling the width and height quadruples the number of pixels, which is why 4K needs five or six times the bitrate of 1080p rather than twice. If a 4K export looks soft, the cause is usually a bitrate set for 1080p rather than a problem with the camera.
FAQ
What bitrate should I use for 1080p video?
For 1080p at 30 frames per second, a good starting point is 8 to 12 Mbps for streaming and 12 to 20 Mbps for a high-quality local file. Fast-moving scenes, such as sports, need the higher end, while a still presentation or talking-head video looks fine at the lower end. For 1080p at 60 frames per second, add roughly 50 percent.
What is the difference between Mbps and MB?
Mbps measures speed: megabits per second. MB measures size: megabytes. One byte holds 8 bits, so a 10 Mbps stream carries 1.25 megabytes every second. That is why a 10-minute video at 10 Mbps is about 750 MB, not 10 MB.
Does the audio track count toward the file size?
Yes. The total file size comes from the video bitrate plus the audio bitrate, multiplied by the duration. A 128 kbps audio track adds about 1 MB per minute, and a 320 kbps track adds about 2.4 MB per minute. This calculator has an audio bitrate option so you can include it in the maths.
Why is my exported file bigger than the calculator says?
The usual causes are the audio track, which many people forget, and the difference between 1000-based and 1024-based units. Some tools also add container overhead, thumbnails, or subtitles, and variable bitrate encoding can overshoot its target on busy scenes. If your encoder used a quality setting instead of a fixed bitrate, the file size was never fixed in the first place.
What bitrate do I need for 4K video?
For 4K at 30 frames per second, plan on 35 to 45 Mbps for streaming and 45 to 80 Mbps for a high-quality local file or archive. At 60 frames per second, 4K needs roughly 60 to 100 Mbps. A 10-minute 4K clip at 45 Mbps is about 3.4 GB, so storage adds up fast.