Storage from Bitrate Calculator
Before you record, stream or archive video, it helps to know how much disk it will eat. File size depends on just two things: the bitrate, which is how many bits of data each second of video carries, and the duration. This calculator multiplies the two to get total bits, then divides by 8 to convert to bytes, because storage is measured in bytes while bitrate is measured in bits. A clip at 8 megabits per second running for one hour, which is 3,600 seconds, carries 28,800 megabits, equal to 3,600 megabytes or 3.6 gigabytes. The page reports the result in megabytes and gigabytes using decimal units, where a gigabyte is 1,000 megabytes, the convention used on drive labels and most upload limits. Use it to plan a memory card, size a backup, estimate an upload time, or compare encoding settings. The figure assumes a constant bitrate; for variable bitrate footage, enter the average bitrate over the clip to get a close estimate, and remember that an audio track and the container overhead will add a little more on top. Every figure is computed deterministically from your two inputs, never estimated, with the method and a worked example shown below for verification.
File size is bitrate times duration, converted from bits to bytes: size = bitrate x time / 8. A stream at 8 Mbps for 3,600 seconds produces a file of 3.60 GB.
Storage from bitrate formula
total bits = bitrate (Mbps) x 1,000,000 x time (s)
bytes = total bits / 8
megabytes = bytes / 1,000,000
gigabytes = megabytes / 1,000 (decimal units)
Bitrate in megabits per second multiplied by seconds gives megabits. Dividing by 8 converts to megabytes, and dividing by a further 1,000 converts to decimal gigabytes.
Worked example
A one-hour clip is encoded at 8 Mbps. One hour is 3,600 seconds.
- Total megabits = 8 x 3,600 = 28,800 megabits
- Megabytes = 28,800 / 8 = 3,600 MB
- Gigabytes = 3,600 / 1,000 = 3.6 GB
The file is 3.60 GB. These are the calculator's default inputs, so the result above matches the widget exactly.
One hour of video by bitrate
Decimal gigabytes for a 3,600 second clip at common bitrates.
| Bitrate | Size for 1 hour |
|---|---|
| 4 Mbps | 1.80 GB |
| 8 Mbps | 3.60 GB |
| 16 Mbps | 7.20 GB |
| 25 Mbps | 11.25 GB |
Units of digital storage and data rate: US National Institute of Standards and Technology (NIST).
Storage from bitrate calculator: frequently asked questions
How do you calculate file size from bitrate?
Multiply the bitrate by the duration to get total bits, then divide by 8 to convert bits to bytes. A stream at 8 megabits per second for 3,600 seconds produces 28,800 megabits, which is 3,600 megabytes or 3.6 gigabytes using decimal units.
Why divide by 8?
Bitrate is measured in bits per second, but storage is measured in bytes. One byte is 8 bits, so dividing total bits by 8 converts the figure into bytes before scaling up to megabytes or gigabytes.
Are these decimal or binary gigabytes?
This calculator uses decimal units, where one gigabyte is 1,000 megabytes and one megabyte is 1,000,000 bytes, which is how storage capacity is usually advertised. Operating systems that report binary gibibytes will show a slightly smaller number for the same file.
Does this account for variable bitrate?
It assumes a constant bitrate for the whole clip. For variable bitrate footage, use the average bitrate over the clip to get a close estimate of the final size. Container overhead and audio tracks add a small amount on top.
Is the result computed automatically?
Yes. The page multiplies bitrate by duration and converts to bytes deterministically. No value is estimated or hard-coded, so changing either input updates the file size instantly.
Official sources
- Units of digital storage and data rate: US National Institute of Standards and Technology (NIST). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.