Data storage unit converter from bits to petabytes. Supports both binary (1024) and decimal (1000) bases.
Four tabs: bi-directional unit conversion, a full conversion reference table, storage estimator (photos, video, MP3, documents), and storage-vs-device-capacity check.
Calculator information
📋 How to use this calculator
- Select the Data Conversion tab, then enter a number in the source unit field (e.g., 5 GB) and see the automatic results in all other units (bit, byte, KB, MB, TB, PB).
- Choose a system: Binary (1024-based kibibyte, used for RAM/OS) or Decimal (1000-based kilobyte, used by storage/HDD manufacturers).
- The Conversion Table tab displays a complete reference for converting all units, useful as a cheat sheet.
- The Storage Estimation tab calculates how many files fit in a given capacity: JPEG photos (3-5 MB), RAW photos (25-40 MB), 1080p video (4-6 GB/hour), MP3s (5 MB/song), Word documents (50-500 KB).
- The Storage vs. Needs tab compares device capacities (256 GB, 512 GB, 1 TB) with your estimated usage so you can pick the right size.
🧮 Storage Unit Conversion
Binary: 1 KiB = 1024 B; 1 MiB = 1024 KiB; 1 GiB = 1024 MiB; 1 TiB = 1024 GiB; Decimal: 1 KB = 1000 B; 1 MB = 1000 KB; 1 GB = 1000 MB; 1 TB = 1000 GB
- 1 byte = 8 bits
- Binary (IEC): kibi (Ki), mebi (Mi), gibi (Gi), tebi (Ti), pebi (Pi) - base 2^10
- Decimal (SI): kilo (k), mega (M), giga (G), tera (T), peta (P) - base 10^3
The difference between 1 TB decimal and 1 TiB binary is 1000^4 vs 1024^4 = roughly 10% smaller in binary. That is why a 1 TB HDD only shows as ~931 GB in Windows: manufacturers use decimal, while Windows displays binary. Modern macOS and Linux use decimal for consistency.
💡 Worked example: Checking a 1 TB SSD that appears as 931 GB in Windows
Given:- Capacity listed on the package: 1 TB (decimal)
- Windows Explorer display: 931 GB
- Why the discrepancy?
Steps:- Manufacturers use decimal: 1 TB = 10^12 bytes = 1,000,000,000,000 bytes
- Windows uses binary but labels it GB: 1 Windows GB = 2^30 bytes = 1,073,741,824 bytes
- 1 TB / 1 Windows GB = 1,000,000,000,000 / 1,073,741,824 = 931.32
- So 1 TB decimal = 931.32 GiB (which Windows calls GB)
- No capacity is missing; only the counting method differs
Result: The 1 TB SSD truly holds 1 trillion bytes, equal to 931 GiB as shown in Windows.
❓ Frequently asked questions
What is the difference between KB and KiB?
KB (kilobyte) is the SI decimal unit meaning 1,000 bytes, while KiB (kibibyte) is the IEC binary unit meaning 1,024 bytes. The IEC 80000-13 (2008) standard requires using KiB/MiB/GiB for binary values to avoid ambiguity. Storage manufacturers use decimal (KB), while RAM makers and older operating systems use binary but often label it KB.
How many GB does one hour of 4K video take?
It depends on codec and bitrate. 4K 60fps H.264 at about 100-150 Mbps equals 45-67 GB/hour. 4K H.265 (HEVC) is more efficient: 50-80 Mbps equals 22-36 GB/hour. ProRes 422 for professional editing can reach 600 GB/hour. Netflix 4K streaming is only 7 GB/hour because it uses adaptive bitrate and H.265.
Why does a 1 TB HDD only show 931 GB?
Because of the difference in base counting between storage manufacturers (decimal, 1 TB = 1 trillion bytes) and older Windows systems (binary, 1 GB = 2^30 bytes). No capacity is lost or damaged. The difference is 1 - (10^12 / 2^40) = 9.06%. macOS has used decimal since Snow Leopard, so 1 TB displays as 1 TB.
How much storage is enough for a work laptop?
256 GB is enough for office work (documents, email, a few apps). 512 GB is ideal for software developers (IDEs, containers, libraries). 1 TB is needed for video/photo editors, gamers (modern games are 50-200 GB), or design workstations. For 4K video professionals, plan on a 2 TB internal SSD plus 4-8 TB of external storage.
Bit vs. byte - which is used for internet speed?
Internet speed is always measured in bits per second (bps, Mbps, Gbps), while file transfer speed in the OS is in bytes per second (B/s, MB/s). The conversion is 1 byte = 8 bits, so a 100 Mbps connection delivers a max download of 12.5 MB/s. ISPs use bits because the numbers look bigger (marketing); software uses bytes because files are measured in bytes.
📚 Sources & references
Last updated: May 11, 2026