Video Bitrate Explained: What Bitrate to Use for 720p, 1080p and 4K

File size is simply bitrate multiplied by duration. Because bitrate is measured in bits and file sizes in bytes, divide by 8: file size in megabytes ≈ (video bitrate + audio bitrate in Mbps) × duration in seconds ÷ 8.

For example, a 10-minute (600-second) video at 8 Mbps video plus 0.128 Mbps audio comes to about 8.128 × 600 ÷ 8 ≈ 610 MB. Halve the bitrate and you roughly halve the file. The formula works in reverse too, which is how you calculate the bitrate needed to hit a target size; see our guide on sending large videos for worked examples.

There is no single correct bitrate for a resolution, because the amount of data needed depends on how hard the picture is to compress.

• Resolution: 4K has four times as many pixels as 1080p, but usually needs somewhat less than four times the bitrate because detail compresses more efficiently at higher resolutions.
• Frame rate: 60 fps needs more bitrate than 30 fps, though not twice as much, because consecutive frames are more similar.
• Motion and detail: sports, confetti, water, foliage and handheld camera shake are hard to compress. A static screen recording or a talking head needs far less.
• Noise and grain: low-light footage full of sensor noise eats bitrate, because noise is random detail the encoder cannot predict.
• Codec: H.265, VP9 and AV1 reach similar quality at a lower bitrate than H.264.

A useful public reference is YouTube's published upload recommendations for H.264 in MP4, which at the time of writing (September 2026) list about 5 Mbps for 720p, 8 Mbps for 1080p and 35 to 45 Mbps for 4K at standard frame rates, with higher figures (7.5, 12 and 53 to 68 Mbps) for 48 to 60 fps. Those figures are for uploads that will be re-encoded again by the platform, so they are deliberately generous.

For files people will watch directly, you can usually go lower. The ranges below are practical starting points for H.264 at 24 to 30 fps; for H.265 or VP9 you can typically use a noticeably lower figure.

• 480p: 1 to 2.5 Mbps.
• 720p: 2.5 to 5 Mbps.
• 1080p: 4 to 8 Mbps for general footage; 2 to 4 Mbps is often enough for screen recordings and talks.
• 1440p: 8 to 16 Mbps.
• 4K (2160p): 15 to 45 Mbps depending on motion; archive masters can justify more.
• Audio: 128 kbps AAC is fine for speech and casual viewing; 192 to 256 kbps for music.

Constant bitrate (CBR) spends the same amount of data every second. It is predictable, which suits live streaming, but wastes data on easy scenes and starves complex ones.

Variable bitrate (VBR) aims for an average and lets the encoder spend more on difficult moments and less on simple ones. For a file of a given size it almost always looks better than CBR. Quality-based modes such as CRF in x264 target a consistent quality instead of a size, so the file size varies with the content. Most browser-based encoders, including the WebCodecs encoders our tools use, work with a target bitrate rather than a quality number.

Too little bitrate shows up first where the encoder struggles: blocky patches in dark gradients and skies, smeared detail during fast motion, and a pulsing effect where the picture sharpens on each keyframe. If you only see problems in fast scenes, a modest increase usually fixes them.

Too much bitrate is harder to spot because it looks fine; it just wastes space. A simple test is to encode a short, busy section at two bitrates and compare them at full screen. If you cannot tell them apart, use the lower one.

The Video Compressor is the quickest way to lower the bitrate: its sliders reduce bitrate and resolution as a percentage of the original, and it shows an estimated output size before you start. The Video Converter gives more direct control, letting you choose the codec, resolution and bitrate alongside the output format. Both run in your browser, so files stay on your device.

Raising the bitrate of an existing file never adds detail that was not there. It only makes the file bigger, so there is no benefit to re-encoding a video at a higher bitrate than its source.