Why is 1KB=1024B instead of 1000B? How to distinguish decimal and binary?
Computers use binary (powers of 2) internally; 2^10=1024 is closest to 1000, so computer storage uses 1024 as the unit progression multiple (called binary prefixes like KiB/MiB/GiB in IEC standards). However, for calculation convenience, HDD/USB/SSD manufacturers usually use decimal (1KB=1000B, SI standard) for product labeling. This creates the "labeling discrepancy": for example, a nominal 500GB hard drive (500×10⁹ bytes) shows as about 465GiB in the operating system (500×10⁹÷1024³≈465.7 GiB, often labeled as GB by operating systems). This tool converts according to computer binary standards (1024).
What is the difference between bit and Byte? Why does 8Mbps broadband only download at about 1MB/s?
bit is the smallest data unit in computers, with only two states 0 and 1, represented by lowercase b; Byte is the basic storage unit consisting of 8 bits, represented by uppercase B; one English character takes 1B, one Chinese character usually takes 2-3B (UTF-8 encoding). Network bandwidth units use bits (e.g., Mbps megabits per second), file sizes and download speeds use Bytes (e.g., MB/s megabytes per second), so theoretical download speed = bandwidth ÷ 8: 100Mbps broadband has a theoretical peak download speed of about 12.5MB/s, actually about 10-11MB/s due to protocol overhead; 500Mbps is about 62.5MB/s; gigabit broadband is about 125MB/s.
What is the difference between KB and KiB? What about MB and MiB?
This is a unit prefix standard issue: traditionally KB/MB/GB mixed two multiples (1000 and 1024), causing confusion. In 1998 the International Electrotechnical Commission (IEC) introduced new prefixes to distinguish: KiB (kibibyte)=1024B, MiB (mebibyte)=1024KiB, GiB (gibibyte)=1024MiB, using lowercase i to explicitly indicate binary; while KB/MB/GB are defined as 1000 multiples per SI International System of Units. But in practice, operating systems (Windows, Linux), memory, and file size labeling still commonly use KB/MB/GB to represent 1024 multiples; only hard drive manufacturers and Mac OS (some versions) use 1000 multiples. This tool uses 1024 multiples following traditional computing convention.
How big is a 2-hour HD movie? File size reference for different resolutions
Common video file size reference: 480P SD about 500MB-1GB per movie; 720P HD about 1-2GB per movie; 1080P Full HD about 2-5GB per movie (H.264 encoding); 4K UHD about 10-30GB per movie (about 15-20GB with H.265 encoding, up to 40-60GB with H.264); Blu-ray original 1080P about 25-50GB, 4K UHD Blu-ray about 50-100GB. One HD JPEG photo about 3-8MB, one MP3 song about 3-8MB, lossless FLAC music about 20-50MB per song; Word documents tens of KB to several MB; WeChat chat history may take several GB to tens of GB per year.
How much usable space does 128GB/256GB/512GB phone storage actually have?
Phone storage capacity differences come mainly from two points: 1) System usage: iOS/Android system itself takes 8-20GB; 2) Decimal vs binary difference: nominal 256GB actually has about 238GiB available space in the system. Therefore 128GB actually has about 105-115GB available; 256GB has about 215-230GB available; 512GB has about 450-480GB available; 1TB has about 930-960GB available. Daily usage: system + common apps take about 30-60GB, photos/videos (based on 5000 photos + 500 videos) about 50-100GB, WeChat cache (heavy use) up to 50-100GB, games (3-5 large games) about 30-80GB; 128GB is sufficient for light users, heavy users recommend 256GB or more.
How to choose 8GB/16GB/32GB RAM? Memory requirements for different uses
RAM is temporary storage for running programs; data is cleared when power is off. Requirements reference: daily office work (Office, under 20 web pages, video watching) 8GB is sufficient; multitasking office work + light creation (basic PS, light programming, VMs) recommend 16GB; 4K video editing, 3D modeling, large games, heavy multitasking (dozens of browser tabs + multiple IDEs + VMs) recommend 32GB; professional workstations (8K editing, AI training, large simulations) 64GB or more. Note: memory must be converted in 1024 multiples; there is no such thing as "how much actual 16GB RAM there is", all operating systems calculate memory capacity by 1024.
What are hard drive TB and PB? How big is big data?
1TB=1024GB: can store about 250,000 HD photos (4MB each), 250 1080P movies, or hundreds of hours of HD video. 1PB=1024TB≈1 million GB: true big data scale; Google processes about 20PB+ of data per day, Baidu index data is at EB level (1EB=1024PB), Facebook adds about 4PB of data daily. Individual users generate about 1-10TB of data in a lifetime (photos, videos, documents); enterprise data warehouses usually start at tens of TB; large internet company data centers are at EB level.
Why can 32-bit systems only recognize a maximum of 4GB RAM? What about 64-bit?
32-bit CPUs have 32 address lines, can address 2^32=4,294,967,296 memory addresses = about 4GB (4096MB); after deducting system reserved and I/O address mapping, Windows 32-bit systems actually have about 3.2-3.5GB RAM available. 64-bit CPUs theoretically address 2^64=16EB (16×1024⁶ bytes≈18.44 million TB), far exceeding current hardware actual needs; Windows 64-bit systems (Win10/11 Pro) support up to 2TB physical RAM, enough for decades to come. This is why all new computers and new phones are 64-bit systems now.
What is the difference between 128GB SSD and 512GB SSD? Besides capacity, what else differs?
Besides capacity differences, same-model SSDs with larger capacity usually have better performance and longer lifespan: 1) Write endurance (TBW): 512GB TBW (Terabytes Written) is about 4 times that of 128GB because data can be written distributed across more flash particles; 2) Write speed: large-capacity SSDs have more parallel channels, sustained write speeds are usually faster; 3) Full-disk performance: SSD performance drops when utilization exceeds 70-80%, 512GB leaves more free space which helps maintain performance. For most users 512GB-1TB is the sweet spot for value; 128GB is only suitable for light office work or as a system drive.
Is cloud drive "unlimited space" credible? Common cloud drive capacity units
Mainstream cloud drives in China: Baidu Netdisk free version about 200GB-2TB (expandable via events), Alibaba Cloud Drive free 100GB+ paid 1TB-20TB, OneDrive free 5GB+Microsoft365 subscription gives 1TB, Google Drive free 15GB, iCloud free 5GB+paid 50GB/200GB/2TB. Note: "unlimited space" is usually promotional during events or specific plans; cloud drive providers reserve the right to adjust; units-wise cloud drives usually use both 1024 and 1000 (may mix at different stages), actual storable file amount prevails. For important data backup, recommend local + cloud dual backup.
How to convert internet speed Mbps to file size MB/s?
Internet speed (bandwidth) unit is Mbps (megabits per second, lowercase b), download speed is MB/s (megabytes per second, uppercase B); conversion: MB/s = Mbps ÷ 8. Common bandwidth corresponding to theoretical download speed: 10Mbps≈1.25MB/s, 50Mbps≈6.25MB/s, 100Mbps≈12.5MB/s, 300Mbps≈37.5MB/s, 500Mbps≈62.5MB/s, 1000Mbps (gigabit)≈125MB/s. Actual download speed is affected by network overhead (about 5-15%), server speed limits, WiFi loss, etc., usually 80-90% of theoretical value. This tool can directly convert Mbps to MB/s: for example, put Mbps value in bit position for conversion, divide result by 8 to get MB/s.
Which storage units does this tool support? What is the relationship with data transfer rate?
This data storage converter supports 7 units: bit (b), B (Byte), KB (kilobyte), MB (megabyte), GB (gigabyte), TB (terabyte), PB (petabyte), all converted using binary 1024 multiples. Note: this tool converts "data volume/capacity size" (static dimension), not "data transfer rate" (dynamic dimension, units like Mbps/MB/s). Data transfer rate requires dividing capacity unit by time unit (seconds); for network speed Mbps conversion please refer to the bandwidth conversion instructions in FAQ. Data plan units GB/MB are the same units as storage capacity GB/MB; mobile data 1GB=1024MB=1024×1024KB.
