Data Size Converter
Byte, kilobyte, megabyte, gigabyte, terabyte – convert decimal (SI) and binary (IEC)
Calculated in your browser – your inputs are not transmitted and are kept on this device only if you choose
You can type in either field.
Result in Gigabyte (GB)
0.001GB
0.0011 MB equals 0.001 GB.
In all units
Tap a unit to make it the target.
Your value is about 1,000,000 × One text character (ASCII).
- One text character (ASCII)0.000000001 GB
- Your value0.001 GB
- 3.5-inch floppy disk (“1.44 MB” = 1,474,560 B)0.001475 GB
- DVD, single layer (≈ 4.7 GB)4.7 GB
- Blu-ray, single layer (≈ 25 GB)25 GB
Bars on a logarithmic scale, values rounded.
How this was calculated
Both units are converted via the base unit B: 1 MB = 1,000,000 B and 1 GB = 1,000,000,000 B.
RZ-26 · headon.pro
Data sizes: decimal vs. binary
SI system (KB = 1,000 B) and IEC system (KiB = 1,024 B) explained
In information technology there are two systems for file sizes: the decimal SI system and the binary IEC system. In the SI system, all prefixes are powers of ten (kilo = 10³, mega = 10⁶, giga = 10⁹). In the IEC system they are powers of two (kibi = 2¹⁰ = 1,024, mebi = 2²⁰ = 1,048,576, gibi = 2³⁰ = 1,073,741,824). This seemingly small difference adds up significantly for large amounts of data: for a petabyte (PB decimal = 10¹⁵ bytes) compared to a pebibyte (PiB binary = 2⁵⁰ bytes), the difference is already about 12.6%.
Hard drive manufacturers use the decimal system because it makes capacity appear larger. Operating systems (Windows, macOS, Linux), on the other hand, traditionally display capacities in binary units – often mislabeled as "GB" even though GiB is meant. The IEC introduced its own prefixes for the binary system in 1998 (originally in IEC 60027-2, today IEC 80000-13): KiB, MiB, GiB, TiB, PiB. macOS switched to the decimal system in 2009 (with Snow Leopard), which meant the same hard drive suddenly appeared "larger" on macOS than on Windows.
In practice this means: a hard drive advertised as 1 TB (1,000,000,000,000 bytes decimal) is shown by Windows as about 931 GiB. For a 256 GB SSD it would be 238 GiB. The difference grows with size: at 1 TB it is almost 70 GB – nearly 7% of the total capacity. On a 10 TB NAS, an apparently "missing" 680 GB is simply down to this unit difference – the storage capacity is actually present, just calculated differently.
For internet speed and data transfer, the decimal system is almost always used: 100 Mbit/s (megabits per second) means 100,000,000 bit/s = 12.5 MB/s (megabytes per second). Important: internet providers state speeds in Mbit/s, while file sizes are given in MB (megabytes). 1 byte = 8 bits, so: MB/s = Mbit/s ÷ 8. Downloading a 4K video file (about 50 GB) at 100 Mbit/s takes about 50,000 MB ÷ 12.5 MB/s = 4,000 seconds ≈ 66 minutes.
In the cloud and server world, precise data size figures are business-critical: cloud providers bill storage costs in GB (decimal). Database backups, log rotation and storage quotas on Linux systems frequently use GiB. IT administrators should know the difference: a backup script meant to stop at "50 GB" must be configured as 50 GB (decimal) or 46.6 GiB (binary) depending on the system. Our converter shows both systems side by side to help avoid such configuration errors.
Decimal vs. binary: direct comparison
SI system vs. IEC system
- 1 KB = 1,000 bytes
- Decimal (SI): hard drive manufacturers
- 1 KiB = 1,024 bytes
- Binary (IEC): RAM, operating systems
- 1 MB = 1,000,000 bytes
- Decimal: network transfer, modem
- 1 MiB = 1,048,576 bytes
- Binary: file sizes in the operating system
- 1 GB = 1,000,000,000 bytes
- Decimal: hard drives, SSD marketing
- 1 GiB = 1,073,741,824 bytes
- Binary: display in the operating system
Calculation examples
- Formula
- MB ÷ 1,000 = GB
- Value
- 500 MB
- Divisor
- 1,000
- Result
- 0.5 GB
- Hard drive
- 1,000,000,000,000 bytes
- Formula
- Bytes ÷ 1,073,741,824 = GiB
- Divisor
- 1,073,741,824
- Displayed in OS
- ≈ 931.32 GiB
- Formula
- Mbit/s ÷ 8 = MB/s
- Value
- 100 Mbit/s
- Divisor
- 8 (1 byte = 8 bits)
- Result
- 12.5 MB/s
Frequently asked questions about the data size converter
Everything about byte, KB, MB, GB, TB and the decimal/binary difference
How many MB are in a GB?
It depends on the system used. In the decimal SI system: 1 GB = 1,000 MB. In the binary IEC system: 1 GiB (gibibyte) = 1,024 MiB (mebibyte). Hard drive manufacturers use the decimal system (1 GB = 1,000,000,000 bytes), which is why a drive sold as "1 TB" often shows only about 931 GiB in the operating system.
What is the difference between GB and GiB?
GB (gigabyte) = 10⁹ = 1,000,000,000 bytes (decimal SI system). GiB (gibibyte) = 2³⁰ = 1,073,741,824 bytes (binary IEC system). The difference is about 7.4%. Operating systems like Windows display hard drive sizes in GiB, while manufacturers advertise in GB (decimal) – hence the apparently "smaller" capacity in the operating system.
How many bytes does a kilobyte have?
Decimal (SI): 1 kB = 1,000 bytes. Binary (IEC): 1 KiB (kibibyte) = 1,024 bytes. Historically, "kilobyte" was often used for 1,024 bytes (since 2¹⁰ = 1,024 is the nearest power of two to 1,000). To resolve the confusion, the IEC introduced the binary prefixes Ki, Mi, Gi, etc. in 1998.
Why does my 1 TB hard drive only show 931 GB in the system?
Hard drive manufacturers advertise 1 TB = 1,000,000,000,000 bytes (decimal). The operating system displays the size in GiB (binary): 1,000,000,000,000 ÷ 1,073,741,824 ≈ 931 GiB. The hard drive actually has the stated capacity – it's just a matter of units. Our converter shows both systems so you can compare the difference directly.
How fast does a 4 GB file download at 100 Mbit/s?
4 GB = 4,000 MB = 32,000 Mbit. At a speed of 100 Mbit/s: 32,000 ÷ 100 = 320 seconds ≈ 5 minutes 20 seconds. Important: internet speeds are given in Mbit/s (megabits per second), while file sizes are given in MB (megabytes). 1 byte = 8 bits, so convert file sizes to bits and divide by the bitrate.