Bitrate File Size Calculator

Calculate file size, bitrate, or duration for audio and video files. Includes presets for common formats and streaming platforms.

Bitrate:

Duration:

h m s

File Size:

Audio Presets

Video Presets

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Results

Understanding Bitrate and File Size

What is Bitrate?

Bitrate is the amount of data processed per unit of time in a digital file, typically measured in bits per second (bps), kilobits per second (kbps), or megabits per second (Mbps). Higher bitrates generally mean better quality but larger file sizes.

File Size Formula

File Size (bytes) = (Bitrate in bps × Duration in seconds) / 8

We divide by 8 because there are 8 bits in 1 byte. Storage is measured in bytes while transmission is measured in bits.

Common Bitrate Ranges

Audio Formats

Format	Typical Bitrate	Quality	Use Case
MP3 Low	64-96 kbps	Acceptable	Voice, podcasts, low bandwidth
MP3 Standard	128 kbps	Good	Music, general listening
MP3 High	320 kbps	Excellent	High-quality music
AAC	128-256 kbps	Good to Excellent	iTunes, YouTube, streaming
FLAC	800-1,400 kbps	Lossless	Audiophile, archival
WAV/PCM	1,411 kbps	Uncompressed	Professional audio

Video Formats

Resolution	Typical Bitrate	Frame Rate	Use Case
480p SD	2.5 Mbps	30fps	Mobile, low bandwidth
720p HD	5 Mbps	30fps	HD streaming
1080p FHD	8 Mbps	30fps	Full HD streaming
1080p FHD	12 Mbps	60fps	High frame rate content
1440p QHD	16 Mbps	30fps	High-quality streaming
2160p 4K	35-45 Mbps	30fps	4K streaming, Blu-ray
4320p 8K	100+ Mbps	30fps	Ultra high-end content

CBR vs VBR Encoding

Constant Bitrate (CBR)

Maintains the same bitrate throughout the entire file
File size is perfectly predictable
May waste space on simple content or compromise quality on complex content
Better for streaming applications

Variable Bitrate (VBR)

Adjusts bitrate based on content complexity
More efficient use of storage space
Better quality at similar average file sizes
File size less predictable (use average bitrate for estimation)

Codec Efficiency

Different codecs compress data with varying efficiency:

H.264/AVC: Widely compatible, good compression, used by most platforms
H.265/HEVC: 25-50% better compression than H.264, same quality at half the bitrate
VP9: Google's codec, similar to H.265, used by YouTube
AV1: Next-gen codec, 30% better than H.265, growing adoption
AAC: Better quality than MP3 at same bitrate
Opus: Excellent for voice and music, very efficient

Storage Planning

When planning storage, consider:

Total duration of content you want to store
Quality level needed for your use case
Available bandwidth for streaming or downloading
Device compatibility (some devices don't support newer codecs)
Overhead from file system and metadata (typically 2-5%)

Pro Tip: For archival purposes, use higher bitrates than you think you need. Storage is cheap, but you can't recover quality lost to aggressive compression. For streaming, match bitrate to your target audience's typical bandwidth.

Example Calculations

Example 1: MP3 File Size

A 3-minute song encoded at 128 kbps:

Duration: 3 minutes = 180 seconds
Bitrate: 128 kbps = 128,000 bps
File Size = (128,000 × 180) / 8 = 2,880,000 bytes = 2.88 MB

Example 2: 1080p Video File Size

A 10-minute video at 1080p 30fps (8 Mbps):

Duration: 10 minutes = 600 seconds
Bitrate: 8 Mbps = 8,000,000 bps
File Size = (8,000,000 × 600) / 8 = 600,000,000 bytes = 600 MB

Example 3: Storage Capacity

How many 3-minute songs at 320 kbps fit on a 16GB device?

File size per song: (320,000 × 180) / 8 = 7,200,000 bytes = 7.2 MB
Available space: 16 GB = 16,000 MB (using 1000MB = 1GB for simplicity)
Number of songs: 16,000 / 7.2 = 2,222 songs

Privacy & Limitations

All calculations run entirely in your browser -- nothing is sent to any server.
Results are computed using standard formulas and should be verified for critical applications.

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Bitrate File Size Calculator FAQ

How do I calculate file size from bitrate?

File size equals bitrate multiplied by duration, then divided by 8 to convert from bits to bytes. For example, a 128 kbps MP3 that is 3 minutes long is about 2.88 MB.

What bitrate should I use for high-quality audio?

For MP3, 320 kbps is considered high quality. For AAC, 256 kbps provides excellent quality. For lossless audio, FLAC typically uses 800-1400 kbps depending on the content.

What is a good bitrate for 1080p video?

For 1080p video at 30fps, 8-12 Mbps is recommended for good quality. For 60fps, 12-16 Mbps is better. YouTube recommends 8 Mbps for 1080p30.

What is the difference between CBR and VBR?

CBR (Constant Bitrate) maintains the same bitrate throughout the file, making file size predictable. VBR (Variable Bitrate) adjusts bitrate based on content complexity, often resulting in better quality at lower average file sizes.

What is the difference between kbps and Mbps?

Kbps (kilobits per second) equals 1,000 bits per second, while Mbps (megabits per second) equals 1,000,000 bits per second. So 1 Mbps = 1,000 kbps. Video typically uses Mbps while audio uses kbps.

How much video can I store on a 64GB device?

It depends on bitrate. At 1080p quality (8 Mbps), about 17 hours. At 4K quality (45 Mbps), only about 3 hours. Lower quality 480p (2.5 Mbps) allows up to 56 hours.