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Understanding Digital Storage Units
Digital storage is measured in bytes: a byte is 8 bits, and each bit is a single 0 or 1 in binary. From there, units scale up by factors of 1,000 (decimal) or 1,024 (binary).
Decimal vs Binary Units
There are two competing standards for measuring digital storage, and the difference matters:
| Decimal (SI) | Binary (IEC) | Difference |
|---|---|---|
| 1 kB = 1,000 bytes | 1 KiB = 1,024 bytes | 2.4% |
| 1 MB = 1,000,000 bytes | 1 MiB = 1,048,576 bytes | 4.9% |
| 1 GB = 1,000,000,000 bytes | 1 GiB = 1,073,741,824 bytes | 7.4% |
| 1 TB = 1,000,000,000,000 bytes | 1 TiB = 1,099,511,627,776 bytes | 10% |
This is why a “1 TB” hard drive shows up as ~931 GiB in your operating system: the manufacturer uses decimal, but your OS reports in binary.
Common Byte Conversions
Decimal Scale
| Unit | Bytes | Abbreviation |
|---|---|---|
| Kilobyte | 1,000 | kB |
| Megabyte | 1,000,000 | MB |
| Gigabyte | 1,000,000,000 | GB |
| Terabyte | 1,000,000,000,000 | TB |
| Petabyte | 1,000,000,000,000,000 | PB |
Quick Conversions
1 GB = 1,000 MB
1 TB = 1,000 GB
1 PB = 1,000 TB
1 byte = 8 bits
1 MB = 8 Mb (megabits)
The lowercase b means bits, uppercase B means bytes. Internet speeds are usually measured in megabits per second (Mbps), while file sizes are in megabytes (MB). To convert: 100 Mbps = 12.5 MB/s.
How Much Storage Do You Need?
| Content Type | Average Size | Files per GB |
|---|---|---|
| Text document | 50 kB | 20,000 |
| High-res photo | 5 MB | 200 |
| MP3 song | 4 MB | 250 |
| 1080p video (per min) | 150 MB | ~7 min |
| 4K video (per min) | 400 MB | ~2.5 min |
Storage Planning Example
Planning storage for a photography project:
| Note | Result |
|---|---|
| photos per shoot = 200 | 200 |
| photo size = 25 MB | 25 MB |
| shoots per month = 4 | 4 |
| monthly storage = photos per shoot × photo size × shoots per month | 20,000 MB |
| annual storage = monthly storage × 12 | 240,000 MB |
The right pane shows monthly storage as 20,000 MB (or 20 GB after monthly storage in GB) and annual storage as 240,000 MB.
Free Byte Converter
Convert between bits, bytes, kilobytes, megabytes, gigabytes, terabytes, and more in both decimal and binary units.
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Example
How many megabytes in 2 TB?
| Note | Result |
|---|---|
| size = 2 TB | 2 TB |
| size in GB | 2,000 GB |
| size in MB | 2,000,000 MB |
The right pane shows 2,000 GB and 2,000,000 MB using the decimal (SI) standard.
Frequently Asked Questions
How many megabytes are in a gigabyte?
In the decimal (SI) standard used by storage manufacturers, 1 GB = 1,000 MB. In the binary (IEC) standard used by operating systems, 1 GiB = 1,024 MiB. The decimal standard is more common in everyday use, but the binary standard reflects how computers actually address memory.
Why does my hard drive show less space than advertised?
Hard drive manufacturers use the decimal standard (1 GB = 1,000,000,000 bytes), while operating systems typically report in binary (1 GiB = 1,073,741,824 bytes). A “1 TB” drive contains 1,000,000,000,000 bytes, which your OS displays as approximately 931 GiB.
What is the difference between Mbps and MB/s?
Mbps (megabits per second) measures network speed, while MB/s (megabytes per second) measures data transfer rate. Since 1 byte = 8 bits, divide Mbps by 8 to get MB/s. A 100 Mbps internet connection downloads at about 12.5 MB/s in ideal conditions.
For converting between number bases used in computing, check our hex to decimal converter. For other unit conversions, see the unit converter. And because storage units scale the same way named numbers do, the large number notation guide shows how to write a petabyte’s worth of zeros as a single suffix.
Convert Data Units in Notes Calculator
Notes Calculator supports both decimal and binary digital storage units:
| Note | Result |
|---|---|
| photo size = 5 MB | 5 MB |
| photos = 10000 | 10,000 |
| total = photo size * photos | 50,000 MB |
| total in GB | 50 GB |
| // Binary units | |
| 1 TB in GiB | 931.32 GiB |
| 1024 KiB in MiB | 1 MiB |
| // Network speed to transfer rate | |
| internet speed = 100 Mb | 100 Mbit |
| internet speed in MB | 12.50 MB |
| // How long to download a file? | |
| file size = 4 GB | 4 GB |
| file size in Mb | 32,000 Mbit |
The app distinguishes between bits (b, kb, Mb, Gb) and bytes (B, kB, MB, GB), and supports binary units (KiB, MiB, GiB, TiB) alongside decimal ones. Variables let you plan storage needs interactively: change photos and see the total update in real time.