Data Size Converter
Convert between bits, bytes, KB, MB, GB, TB, PB and IEC binary units (KiB, MiB, GiB).
SI: 1 KB = 1,000 bytes. IEC: 1 KiB = 1,024 bytes.
How to Use
Select the data unit
Choose decimal (KB, MB, GB) or binary (KiB, MiB, GiB) units depending on your context.
Enter the value
Type the amount and all equivalent unit values appear immediately.
Check decimal vs binary
Manufacturers use decimal (1 GB = 1,000 MB); operating systems use binary (1 GiB = 1,024 MiB).
Convert bits to bytes
For internet speeds, divide Mbps by 8 to get the MBps (megabytes per second) download rate.
Understanding Digital Storage Units
Digital storage is measured in bits and bytes. One byte contains 8 bits. Confusion arises from two different systems: decimal (SI) units used by manufacturers and binary (IEC) units used by operating systems. A 1 TB hard drive is actually 1,000 GB in manufacturer's decimal units, but appears as ~931 GB (1 TiB) in your computer's binary system.
SI (Decimal) Units - Used by Manufacturers
- 1 Kilobyte (KB) = 1,000 bytes
- 1 Megabyte (MB) = 1,000,000 bytes
- 1 Gigabyte (GB) = 1,000,000,000 bytes
- 1 Terabyte (TB) = 1,000,000,000,000 bytes
- 1 Petabyte (PB) = 1,000,000,000,000,000 bytes
IEC (Binary) Units - Used by Operating Systems
- 1 Kibibyte (KiB) = 1,024 bytes
- 1 Mebibyte (MiB) = 1,048,576 bytes
- 1 Gibibyte (GiB) = 1,073,741,824 bytes
- 1 Tebibyte (TiB) = 1,099,511,627,776 bytes
- 1 Pebibyte (PiB) = 1,125,899,906,842,624 bytes
The Storage Capacity Discrepancy Explained
When you buy a "1 TB" hard drive, manufacturers rate it as 1,000,000,000,000 bytes (using decimal/SI units). However, Windows and Mac display storage using binary (IEC) units (1,024 multipliers). Result: Your 1 TB drive shows as approximately 931 GiB. This 7% discrepancy occurs with every storage device and is often a source of consumer confusion.
Real-World Storage Conversions
- 1 GB (manufacturer) = 1,000 MB = 1,000,000 KB
- 1 GiB (computer system) = 1,024 MiB = 1,048,576 KiB
- A 500 GB external hard drive = ~465 GiB on your computer
- A 4GB USB drive = 4,000,000,000 bytes claimed vs ~3.73 GiB actually usable
- Internet speeds: 100 Mbps (megabits per second - different from MB/s!)
Common Applications
- Storage Shopping: Understanding why purchased storage appears smaller on your device
- File Transfers: Estimating how long downloads will take based on file size and connection speed
- Cloud Storage: Services quota is typically specified in GB but displayed using both systems
- Video Production: High-quality video files require massive storage; accurate size calculations prevent over-allocating disk space
- Backups: Planning backup solutions requires knowing total data size
Frequently Asked Questions
Why does my hard drive show less storage than advertised?
Manufacturers advertise storage in decimal units (GB). Your operating system displays storage in binary units (GiB). A 1 TB drive (1,000 GB decimal) equals approximately 931 GiB binary. Additionally, operating systems reserve space for boot files and system files, further reducing available space from the advertised amount.
How many gigabytes is a terabyte?
In decimal (manufacturer) units: 1 TB = 1,000 GB. In binary (operating system) units: 1 TiB = 1,024 GiB. Technically, 1 TB = 1,000 GB ≠ 1 TiB (which is larger by 2.4%).
What is a bit versus a byte?
A bit is the smallest unit of data (binary: 0 or 1). A byte contains 8 bits and is the standard storage unit. Internet speeds measure in bits per second (Mbps); storage measures in bytes. This is why a 100 Mbps internet connection downloads ~12.5 MB per second (100 ÷ 8).
Why do different companies use KB, MB, and GB inconsistently?
Storage manufacturers use decimal/SI units (1 KB = 1,000 bytes). Operating systems use binary/IEC units (1 KiB = 1,024 bytes). File managers may label binary units as "KB" even though technically it should be "KiB". This dual-system approach creates consistent confusion.
How much video storage does 1 TB provide?
Depends on video quality and compression: 1 TB holds approximately 250 hours of 720p HD video, or 50 hours of 4K Ultra HD video. Original 1 TB = 1,000 GB decimal ≈ 931 GiB actual usable space.
What is the relationship between Mbps and MBps?
Mbps = Megabits per second (internet speed). MBps = Megabytes per second (file transfer speed). They differ by a factor of 8: 1 MBps = 8 Mbps. A 100 Mbps internet connection theoretically downloads at 12.5 MBps maximum.
Real-World Examples & Use Cases
Storage Device Shopping
Understanding why your purchased storage always appears smaller on your device requires knowing the decimal/binary unit confusion. A 2 TB external drive advertised with decimal units holds 2,000,000,000,000 bytes, but Windows reports it as approximately 1.82 TiB. The missing space is not lost — it is simply described in different unit systems. Knowing this conversion prevents frustration and helps you accurately compare storage products from different manufacturers.
Internet Speed Planning
Internet service providers advertise speeds in Mbps (megabits per second), but file download progress bars show MBps (megabytes per second). A 100 Mbps connection downloads at approximately 12.5 MBps. When planning how long it takes to download a 4 GB game (4,000 MB = 32,000 Mb), dividing by your connection speed in Mbps gives the download time in seconds. Understanding this bits-to-bytes relationship is essential for planning downloads and streaming quality requirements.
Cloud Storage & Backup Planning
Cloud storage services (Google Drive, Dropbox, iCloud) advertise in GB (decimal), while your computer's folder size calculations may vary. When estimating whether your photo library (say, 25,000 photos at average 4 MB each = 100 GB) fits in a storage plan, unit conversion ensures you're making accurate comparisons. Video files especially vary: a 4K video can be 500 MB to 2 GB per minute depending on bitrate and compression codec.
IT & Network Administration
Network administrators calculate bandwidth allocation, storage provisioning, and backup window requirements using data size conversions daily. A 10 Gbps network link can theoretically transfer 1.25 GB of data per second. Planning backup jobs that must complete within a 4-hour maintenance window requires knowing the maximum data throughput in the right units. Database sizes, log file growth rates, and storage RAID capacities all involve converting between bits, bytes, and their decimal and binary multiples.
How It Works
Digital storage uses two competing measurement systems: Decimal (SI) system — used by storage manufacturers: 1 KB = 1,000 bytes (10³) 1 MB = 1,000,000 bytes (10⁶) 1 GB = 1,000,000,000 bytes (10⁹) 1 TB = 1,000,000,000,000 bytes (10¹²) Binary (IEC) system — used by operating systems: 1 KiB = 1,024 bytes (2¹⁰) 1 MiB = 1,048,576 bytes (2²⁰) 1 GiB = 1,073,741,824 bytes (2³⁰) 1 TiB = 1,099,511,627,776 bytes (2⁴⁰) The gap grows with size: - At GB level: 1 GB = 0.9313 GiB (6.9% difference) - At TB level: 1 TB = 0.9095 TiB (9.1% difference) Bits vs bytes: 1 byte = 8 bits. Internet speeds in Mbps ÷ 8 = file transfer speed in MBps.
Frequently Asked Questions
Why does my 1 TB hard drive show less space in Windows?▼
What is the difference between GB and GiB?▼
How fast does a 100 Mbps connection download files?▼
How many MB is 1 GB?▼
How big is a petabyte?▼
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