Tech calculator
Data Storage Converter
Instantly convert between all storage units: bits, bytes, kilobytes, megabytes, gigabytes, terabytes, and their binary counterparts. Understand the difference between decimal and binary storage units.
Converted values
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How the data storage converter works
Enter a storage capacity value and select the unit you're converting from. The converter transforms the value into every other unit, showing both decimal units (KB, MB, GB, TB, PB) and binary units (KiB, MiB, GiB, TiB, PiB), as well as bits and bytes. Everything flows through a single calculation in bytes, the fundamental unit of digital storage.
Decimal versus binary units
Storage manufacturers define units using powers of 1,000 (decimal), but computer systems often measure in powers of 1,024 (binary). This mismatch is the source of much confusion and the reason a "1 TB" hard drive holds only about 931 GB when reported by Windows or macOS.
Hard drive and SSD manufacturers advertise capacity in decimal units: a "1 TB" drive holds 1,000,000,000,000 bytes. Windows and macOS, however, display sizes in binary units (1 GiB = 1,024³ bytes) but label them as GB. Converting: 1,000,000,000,000 bytes ÷ 1,073,741,824 bytes per GiB ≈ 931.32 GiB, which shows as ~931 GB. The drive is not defective; the units are simply different.
All the units defined
Here are the exact definitions used by the converter, with byte factors listed for reference.
- Bit: 1/8 byte (0.125 bytes) — the smallest unit; 8 bits make 1 byte
- Byte (B): 1 byte — the fundamental unit of digital storage
- Kilobyte (KB): 1,000 bytes — 10³ bytes
- Megabyte (MB): 1,000,000 bytes — 10⁶ bytes
- Gigabyte (GB): 1,000,000,000 bytes — 10⁹ bytes
- Terabyte (TB): 1,000,000,000,000 bytes — 10¹² bytes
- Petabyte (PB): 1,000,000,000,000,000 bytes — 10¹⁵ bytes
- Kibibyte (KiB): 1,024 bytes — 2¹⁰ bytes
- Mebibyte (MiB): 1,048,576 bytes — 2²⁰ bytes
- Gibibyte (GiB): 1,073,741,824 bytes — 2³⁰ bytes
- Tebibyte (TiB): 1,099,511,627,776 bytes — 2⁴⁰ bytes
- Pebibyte (PiB): 1,125,899,906,842,624 bytes — 2⁵⁰ bytes
Bits versus bytes
A byte contains 8 bits. File sizes are measured in bytes (MB, GB), but internet speeds are typically measured in bits per second (Mbps, Gbps). A 100 Mbps connection moves 100 million bits per second, which is 12.5 megabytes per second. This 8-fold difference is why downloads often feel eight times slower than your advertised internet speed.
A 1 Gbps (1 gigabit per second) connection, advertised as "gigabit internet", actually downloads at 125 MB/s (1 gigabyte per second ÷ 8). Mixing up Mbps and MB/s is one of the most common sources of confusion in discussions of file sizes and connection speeds.
Frequently asked questions
Why does my 1 TB hard drive show only 931 GB in Windows?
Drive makers use decimal units (1 TB = 10¹² bytes), but Windows displays sizes in binary units (1 GiB = 2³⁰ ≈ 1.07 billion bytes) while still calling them GB. The conversion is 1,000,000,000,000 bytes ÷ 1,073,741,824 bytes per GiB ≈ 931 GiB, shown as ~931 GB. The drive holds its full rated capacity; the units are just different.
What is the difference between MB and MiB?
MB (megabyte) is a decimal unit equal to 1,000,000 bytes. MiB (mebibyte) is a binary unit equal to 1,048,576 bytes (2²⁰). File sizes are often labeled in decimal MB, while operating systems measure in binary units. One decimal MB is about 95.4% of one binary MiB.
How many MB in a GB?
In decimal units, 1 GB = 1,000 MB. In binary units, 1 GiB = 1,024 MiB. Storage manufacturers and download pages typically use decimal units (1,000), while Windows and macOS default to binary units (1,024), which is why the same file shows different sizes on different systems.
Is a kilobyte 1,000 or 1,024 bytes?
According to the International System of Units (SI), 1 KB = 1,000 bytes. The term kibibyte (KiB) refers to 1,024 bytes. Older software and systems used KB loosely to mean 1,024 bytes, causing confusion, but modern standards define KB as 1,000 bytes and KiB as 1,024 bytes.
How many bits are in a megabyte?
Since 1 byte contains 8 bits, 1 MB contains 8,000,000 bits (using decimal units). A 1 Mbps (megabit per second) connection therefore downloads at 125 KB/s, and a 100 Mbps connection downloads at 12.5 MB/s.