What is the difference between KB and KiB?

KB (kilobyte) uses the SI (decimal) definition: 1 KB = 1,000 bytes. KiB (kibibyte) uses the IEC (binary) definition: 1 KiB = 1,024 bytes. The difference grows at higher prefixes - 1 GB = 1,000,000,000 bytes, while 1 GiB = 1,073,741,824 bytes (about 7% more).

How many bytes are in a megabyte?

In the SI (decimal) system, 1 MB = 1,000,000 bytes. In the IEC (binary) system, 1 MiB = 1,048,576 bytes. Hard drive manufacturers use the decimal system (1 MB = 1,000,000 bytes), while operating systems often report sizes using binary units - which is why a "500 GB" hard drive appears as roughly 465 GB in Windows.

How many bits are in a byte?

There are exactly 8 bits in 1 byte. A bit is the smallest unit of digital data (0 or 1). Internet speeds are typically measured in bits per second (Mbps), while file sizes use bytes.

How do I convert MB to GB?

Divide the value in megabytes by 1,000 to get gigabytes (SI). For example, 5,000 MB = 5 GB. If using binary units, divide mebibytes by 1,024 to get gibibytes: 1,024 MiB = 1 GiB.

Why does my hard drive show less storage than advertised?

Hard drive manufacturers measure in decimal (1 GB = 1,000,000,000 bytes), but operating systems like Windows report storage in binary units (1 GB = 1,073,741,824 bytes). A 1 TB drive has exactly 1,000,000,000,000 bytes, which Windows reports as approximately 931 GiB.

Data Storage Converter (KB, MB, GB, TB)

MB vs MiB: what's the difference?

Two systems define storage prefixes. The SI (decimal) system, used by hard drive manufacturers and internet speeds, defines 1 KB = 1,000 bytes. The IEC (binary) system, used by operating systems when reporting RAM and file sizes, defines 1 KiB = 1,024 bytes. The gap widens at larger sizes:

Common storage conversions

Value	Result
1 byte (B)	8 bits
1 KB	1,000 bytes (decimal)
1 KiB	1,024 bytes (binary)
1 MB	1,000,000 bytes
1 MiB	1,048,576 bytes
1 GB	1,000,000,000 bytes
1 GiB	1,073,741,824 bytes
1 TB	1,000,000,000,000 bytes
1 TiB	1,099,511,627,776 bytes
1 TB	≈ 0.9095 TiB
1 Gbps	125 MB/s
1 Mbps	0.125 MB/s

Why does my hard drive show less space?

A 1 TB hard drive stores exactly 1,000,000,000,000 bytes. Windows reports storage using binary GiB, so it shows roughly 931 GiB (≈ 931 "GB" in Windows terms) instead of 1,000 GB. The drive is not defective; it's a units mismatch.

The binary vs. SI gap

The further up the prefix scale you go, the larger the discrepancy between SI and binary:

SI size	Binary equivalent	Difference
1 KB (1,000 B)	0.977 KiB	−2.3%
1 MB (1,000,000 B)	0.954 MiB	−4.6%
1 GB (10⁹ B)	0.931 GiB	−6.9%
1 TB (10¹² B)	0.909 TiB	−9.1%
1 PB (10¹⁵ B)	0.888 PiB	−11.2%

Download time calculator

To estimate download time: time (seconds) = file size (bits) / speed (bits per second). Example: A 500 MB file over 100 Mbps connection:

500 MB × 8 = 4,000 Mb (megabits)
4,000 Mb / 100 Mbps = 40 seconds (ideal)
Real-world: +20–50% overhead from protocol headers, congestion, etc.

RAID storage considerations

RAID arrays consume more raw disks than usable capacity due to redundancy:

RAID 1 (mirroring): 50% efficiency. 2 × 1 TB = 1 TB usable.
RAID 5: (n−1)/n efficiency. 4 × 1 TB = 3 TB usable (one disk for parity).
RAID 6: (n−2)/n efficiency. 6 × 1 TB = 4 TB usable (two parity disks).
RAID 10: 50% efficiency like RAID 1, but with striping for performance.

Real-world file size examples

High-quality MP3: ~1 MB per minute (320 kbps)
FLAC audio: ~30 MB for a 3-minute song (~1000 kbps)
1080p video (H.264): ~5 GB per hour (high bitrate)
4K video (H.265/HEVC): ~8–15 GB per hour
RAW photo (24 MP): 25–50 MB per image
JPEG photo (24 MP): 5–10 MB per image
Modern AAA game: 50–150 GB installed