High-resolution videos are almost as vivid as the real world. But resolution isn’t the only factor in video quality. Bitrate, or how much data a video needs to play per second, is part of the equation for video creators when creating and presenting videos.
Poor bitrates can cause many common issues, such as dropped frames and bloated file sizes that can throttle internet connections. Not every device can play high-resolution videos, especially without buffering, and bitrate isn’t a matter of “more is better.” It exists in a careful balance with resolution, frame rate, and your video hosting platform’s capacity.
In this guide, we’ll explore what bitrates are and how bitrate affects video quality, and how other factors like file size and compression can make or break a viewing experience.
What does bitrate do in video?: Key concepts
Bitrates influence how viewers perceive video quality, which is a combination of resolution and frame rate. For example, a 1080p video at 60 fps looks crisper and smoother than one at 720p and 30 fps, but it’ll also be a much larger file. That’s because the 1080p video at 60 fps uses more pixels to create each frame, which are then doubled by having twice as many frames per second.
Since bitrates are data in the form of “bits” (units of digital information) from a hosting platform to a device, a high or low bitrate doesn’t affect the video file itself. Instead, it adjusts video buffering and playback quality based on how much of the video can be pushed through an internet connection at a time. In general, a video with higher resolution and frame rate needs a higher bitrate.
Live streaming a video complicates this math because it introduces compression, encoding, and other factors related to internet connectivity that affect video quality on both sides. However, your video’s bitrate determines how much data you can push through at a time so that an optimized bitrate can make a big difference in your live stream.
It’s easy to change a video’s bitrate using video editing software. With tools like Vimeo’s video resizer, you can change a video’s dimensions or resolution to reduce the bitrate you need. This is particularly important for videos shared across multiple platforms (such as social media and standard video hosting platforms) that have different file upload size limits, aspect ratios, and default resolutions.
If your bandwidth, or the viewer’s, can’t accommodate the bitrate streaming, the video will either buffer to catch up (download more packets of data) or become heavily compressed to fit bandwidth limitations, resulting in pixelated, choppy playback. The key to avoiding poor playback is to select the right resolution, framerate, and bitrate from the outset.
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How do you measure video bitrate?
Bitrate is often measured in kilobits per second (Kbps) or megabits per second (Mbps), which are multiples of bits per second. One kilobit is equivalent to 1,000 bits, and one megabit is equivalent to 1,000,000 bits.
Knowing the bitrate can help you diagnose issues with compression, buffering, or video quality. Viewers can check a video’s bitrate on streaming platforms or directly on their devices, and content creators can check it on their hosting platforms before uploading. However, keep in mind that many video services use variable bitrate (VBR), which automatically adjusts the bitrate throughout the video to match the available bandwidth.
Every tool you use to make, edit, and watch a video has its own method of measuring bitrate. Here are a few common ways to check.
File properties and command line
It can be helpful to know your video file’s bitrate before uploading it to an editor, especially if there are file-size constraints. If your video is saved on your local device, you can check its bitrate directly:
- On PC: Right-click the file and select “Properties.” Then, open the Details tab to find the field labeled “Total bitrate.”
- On Mac: Open the file in QuickTime Player and press Command+I to open the Information window. In QuickTime Player, bitrates are called “data rates.” A data rate is another term for bitrate, measuring the speed of the data being transferred.
If you’d like to set or change the file’s bitrate ahead of time, you can use programs like Mplayer to alter the file code via the command line directly.
Streaming software
If you’re live-streaming a video to an audience using streaming software, you can check the bitrate in the program while the stream is active. While the exact placement varies program-to-program, it’s typically in the settings menu, where you can also adjust the bitrate as needed if viewers are mentioning issues with compression or buffering in chat.
Video platform
Some video platforms, especially ones that specialize in live streaming, let viewers check the bitrate of the video they’re watching. It’s typically available in the settings menu, under an “Advanced” category.
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Other factors affecting video quality
Getting the correct bitrate for your videos can be challenging, but it isn’t the only thing that separates high-quality videos from the rest. Here are a few other factors influencing your video quality.
Video frame rate
A video’s frame rate is the number of still images (frames) used to create the video, measured in frames per second (fps). A video with 60 fps appears much smoother than one at 30 fps because more frames are making up every step of the movement you see on the screen. Stop-motion animations are a great example of how frame rate affects video quality: Lower frame rates mean larger jumps, whereas higher frame rates look much smoother and more natural.
Here’s what different bitrates and frame rates do for video performance:
- Higher bitrate, higher video frame rate: The best quality videos have high bitrates and high video frame rates. This is when image clarity is at its best, so they’re ideal for professional gaming, live streaming sports, and other detail-heavy videos with rapid motion. They often come in large file sizes, so be ready to compress the file before uploading it (or choose a streaming platform with built-in compression, like Vimeo).
- Higher bitrate, lower video frame rate: Pairing a higher bitrate with a lower frame rate preserves high-quality streaming, but you may lose details in motion compared to a higher frame rate. This is an ideal balance for films and video content with many lingering close-up shots, or when the little details aren’t as important.
- Lower bitrate, higher video frame rate: A low bandwidth can cause low bitrates even if your video plays at 60fps or higher. This low bitrate means less data is sent to viewers at a time, resulting in lower image quality, such as pixelation and image artifacts, which interrupt the viewing experience.
- Balanced bitrate and video frame rate: As the best option for most content creators, a balanced bitrate and frame rate means viewers don’t have to sacrifice one feature of their video to get the absolute best of the other. A strong balance means smooth motion and crisp images. Adaptive streaming excels at this balance by adjusting both to the viewing device’s capacity.
Video resolution
Video resolution measures the dimensions of a video in pixels. A 1920x1080 (1080p) video has 1,920 pixels horizontally and 1,080 pixels vertically, making a total of 2,073,600 pixels. With so many tiny dots making up the image, a 1080p video offers much greater clarity and detail than the next standard size of 720p, which has 921,600 pixels. However, higher resolutions come with much larger file sizes. There are some newer advanced compression standards, such as HEVC, that support efficient compression of 4k and other high-resolution videos.
Codecs
Codec is short for “coder-decoder” or “compressor-decompressor,” depending on who you ask. Codecs are digital containers that compress a video file to a manageable size and decompress it when needed. Some, like AVI, do minimal compression to ensure videos play at the highest quality without reducing file sizes, which can lead to more lag and buffering. Others, like MPEG-4, are more aggressive with their compression to optimize videos for mobile devices and low-bandwidth internet connections.
FAQ
Why do some videos buffer even with high bitrates?
There are many reasons viewers might get stuck in a buffer loop. Even with a high bitrate, a video might buffer if the user's internet connection's bandwidth isn’t high enough. The higher your bitrate, the higher your bandwidth must be to pass that many bits per second. Other common causes include bottlenecks on the server side (if more people are watching a new release at the same time, straining the server’s bandwidth, for example), outdated device hardware, or a streaming platform that uses an inefficient codec.
How do streaming platforms automatically handle bitrate?
To optimize the viewing experience, streaming platforms use adaptive bitrate (ABR) technology to adjust bitrates to match viewers’ maximum capabilities. ABR generates multiple versions of each video and detects the one that best fits each viewer’s bandwidth, device, and internet speed.
Is there a maximum proper bitrate for different devices or screens?
Technically, but not in practice. The maximum bitrate that’s useful for streaming to any device is equal to the bandwidth of its internet connection. However, devices use bandwidth for more than just playing a video, and many households have more than one device active at a time. Practically, 60% of a viewer’s bandwidth is a good reference point for the maximum proper bitrate.
For example, the average internet download speed in the U.S. is around 200 Mbps. 60% of that is 120 Mbps, which is more than enough bitrate for a 60 fps 4K video. That said, there are still many places with limited bandwidth where your video may buffer or run poorly. England’s average internet bandwidth is just 70 Mbps, for example, so you’re capped at 42 Mbps. Luckily, most streaming platforms use 5 Mbps or less to stream videos up to 4k.
Optimize your videos for multiple platforms with Vimeo
Getting your video’s bitrate right is all about striking the right balance between its resolution, frame rate, and file size. You want smooth motion and crisp visuals, but you also want viewers to be able to watch it from beginning to end without buffering.
Vimeo’s compression tool uses unique techniques to shrink video file size without sacrificing quality. With adaptive streaming that automatically renders the videos in their highest quality based on the viewer’s internet speed, Vimeo hosts beautiful videos from every perspective.
