File size (kilobytes) = bitrate (kbps) × duration (seconds) ÷ 8. Divide by 1,000 for megabytes. For one minute: 96 kbps gives 0.72 MB, 128 kbps gives 0.96 MB, 160 kbps gives 1.2 MB, 192 kbps gives 1.44 MB, 256 kbps gives 1.92 MB, and 320 kbps gives 2.4 MB. Use the reference table and the calculation method below to answer questions like how many songs fit on 1 GB.
The Formula for MP3 File Size Per Minute
Calculating the file size of an MP3 is straightforward. The core relationship: bitrate (in kbps) times duration (in seconds) equals the total number of kilobits of audio data. Divide by 8 to get kilobytes. Divide by 1,000 for decimal megabytes. This works for any length of audio.
To find the size of a 320 kbps MP3 for one minute: 320 kbps × 60 seconds = total kilobits. Divide by 8 for kilobytes. Divide by 1,000. The result is 2.4 MB. The same method works for any bitrate and duration.
MP3 File Size Per Minute at Every Bitrate
Use these numbers to estimate the size of any song or batch. They cover every bitrate offered by this site.
- 96 kbps: 0.72 MB per minute
- 128 kbps: 0.96 MB per minute
- 160 kbps: 1.2 MB per minute
- 192 kbps: 1.44 MB per minute
- 256 kbps: 1.92 MB per minute
- 320 kbps: 2.4 MB per minute
To compare, a 4-minute song at 320 kbps is about 9.6 MB. At 192 kbps it is about 5.8 MB. At 96 kbps it is about 2.9 MB.
How Many Hours Fit on Common Storage Sizes
1 GB of Storage
At 192 kbps, 1 GB (1,000 MB) holds roughly 694 minutes of audio. That is about 11.5 hours. At 128 kbps you can fit more: 1,000 MB ÷ 0.96 MB per minute gives roughly a few more hours. At 320 kbps, 1,000 MB ÷ 2.4 MB per minute gives roughly a longer duration.
Other Storage Sizes
Divide the total MB by the MB per minute for your chosen bitrate. A 2 GB drive at 192 kbps holds about a long duration (many hours). A 4 GB drive at 128 kbps holds about 69 hours.
WAV vs MP3 File Size Comparison
CD-quality WAV audio (16-bit, 44.1 kHz stereo) has a fixed bitrate of 1,411.2 kbps. That works out to about 10.6 MB per minute. A 320 kbps MP3 is 2.4 MB per minute. That makes it roughly a few times smaller. At 128 kbps, an MP3 is about 11 times smaller than the original WAV. This compression is why MP3 dominates portable music and file sharing.
How to Use Bitrate to File Size for Batch Conversion
Plan Your Total Output Size
When converting multiple files, the formula lets you plan your total output size. Follow these steps:
- Determine the total duration of your audio or video files in minutes.
- Choose your target bitrate: 96, 128, 160, 192, 256, or 320 kbps.
- Multiply the total minutes by the MB per minute for that bitrate (for example, 2.4 MB for 320 kbps).
- The result is your approximate total file size in MB.
Account for Overhead
Tags and embedded album art add a small amount on top of the audio. Actual file sizes will be slightly larger than the calculation. Batches on this site are capped at 300 MB total upload. Use this method to stay within the limit.
Practical Examples of File Sizes
To make these numbers concrete:
- A 3-minute pop song at 128 kbps: 3 × 0.96 MB = a few MB
- A 5-minute podcast at 96 kbps: 5 × 0.72 MB = a few MB
- A 10-minute live recording at 256 kbps: 10 × 1.92 MB = a larger amount
- A 45-minute album at 320 kbps: 45 × 2.4 MB = a much larger amount
Bitrate-to-file-size relationships scale linearly with time.
Choosing the Right Bitrate for Your Needs
Match Bitrate to Content
Lower bitrates like 96 kbps suit speech or podcasts where space is a priority. Mid-range bitrates (128 and 160 kbps) offer a good balance for general music listening. Higher bitrates (256 and 320 kbps) preserve more detail. They are preferred for critical listening or archival purposes, at the cost of larger files.
Make the Trade-Off
Use the per-minute sizes above to decide what fits your storage and quality requirements.