Data Storage
Converter & Data Rates
Convert between TB, GB, MB, and binary units like GiB and TiB. Understand why your 1TB drive shows 931GB. Plus convert internet speeds from Mbps to MB/s with real download time estimates.
Decimal units use multiples of 1000. Binary units use multiples of 1024. Windows labels binary units as GB, TB, etc.
Conversion Result
Show Your Work
Select units and enter a value to see the exact conversion formula and real-world context.
How it works
Pick a mode
Choose Data Storage for TB/GB conversions or Data Rate for internet speed math like Mbps to MB/s.
Select your units
Pick from decimal (1000) or binary (1024) storage units, or bit/byte rate units. The dropdown groups make it clear which system you are using.
See the exact math
Get your result with the full formula, real-world context like download times, and explanations for common confusion points.
Explore more free calculators
Also try our Unit Converter, Cooking Converter, and Calculators Hub.
Frequently asked questions
What is the Best Answer Hub Data Storage Converter?
The Best Answer Hub Data Storage Converter is a free, privacy-first browser tool that converts between data storage units and data rate units. It handles both decimal (SI) units like GB and TB that manufacturers use, and binary (IEC) units like GiB and TiB that operating systems use. It also converts internet speeds from Mbps to MB/s so you understand your real download speeds. Everything runs in your browser with no data collection.
Why does my 1 TB hard drive only show 931 GB?
Your drive is labeled in decimal terabytes where 1 TB equals 1,000,000,000,000 bytes. Windows displays capacity in binary gibibytes where 1 GiB equals 1,073,741,824 bytes. When you divide 1,000,000,000,000 by 1,073,741,824, you get approximately 931. Your drive is not defective — Windows is simply using a different counting system and displaying GiB while labeling it as GB.
What is the difference between GB and GiB?
GB stands for gigabyte and uses decimal counting where 1 GB equals 1,000,000,000 bytes. GiB stands for gibibyte and uses binary counting where 1 GiB equals 1,073,741,824 bytes. The difference is about 7.4%. Hard drive manufacturers advertise in GB because the numbers are larger. Windows and macOS report storage in GiB but label it as GB, which causes confusion. The IEC introduced GiB in 1998 to fix this ambiguity.
How many MB are in a GB exactly?
In the decimal system used by manufacturers, 1 GB equals exactly 1,000 MB. In the binary system used by operating systems, 1 GiB equals 1,024 MiB. This 2.4% difference compounds as you move up the scale. At the gigabyte level the gap is 74 MB, but at the terabyte level it grows to 99 GB. Always check whether a spec sheet uses GB or GiB before comparing capacities.
How do I convert Mbps to MB/s?
Divide the megabits per second by 8 to get megabytes per second. For example, 100 Mbps equals 12.5 MB/s. This is because there are 8 bits in 1 byte. Internet service providers advertise speeds in megabits because the numbers are eight times larger and sound more impressive. Our data rate converter handles this automatically and also shows you the theoretical download time for a 1 GB file.
Why is my internet speed 100 Mbps but downloads are only 12.5 MB/s?
100 Mbps is 100 megabits per second. Dividing by 8 gives 12.5 megabytes per second. This is the correct theoretical maximum. Your actual downloads are often slower because of protocol overhead, network congestion, server limitations, and Wi-Fi interference. A realistic sustained download speed is typically 70% to 90% of the theoretical maximum, so 100 Mbps usually delivers 9 to 11 MB/s in practice.
What is the difference between bits and bytes?
A bit is the smallest unit of digital information — a single 0 or 1. A byte is a group of 8 bits. Network speeds are measured in bits per second because data travels one bit at a time over wires and radio waves. File sizes are measured in bytes because computers process data in 8-bit chunks. This is why you always divide internet speed by 8 to estimate download speed in bytes.
How many gigabytes are in a terabyte exactly?
In the decimal system, 1 terabyte equals exactly 1,000 gigabytes. In the binary system, 1 tebibyte equals 1,024 gibibytes. The confusion arises because Windows labels binary tebibytes as terabytes. So when Windows says a drive has 931 GB, it actually means 931 GiB, which equals exactly 1 decimal TB. Our converter lets you switch between both systems instantly.
What is a tebibyte (TiB)?
A tebibyte is a binary unit of digital information equal to 1,099,511,627,776 bytes, or 1,024 gibibytes. The International Electrotechnical Commission introduced tebibyte in 1998 to distinguish binary multiples from decimal multiples. Before that, both systems were called terabytes, which caused widespread confusion. macOS switched to displaying decimal gigabytes in 2009, but Windows still uses binary gibibytes while labeling them as gigabytes.
Why do hard drive manufacturers use decimal but Windows uses binary?
Manufacturers use decimal because it produces larger advertised capacities — a 1 TB drive sounds bigger than a 0.91 TiB drive. Windows uses binary because computers operate in base-2, so memory and file systems are naturally organized in powers of 2. This mismatch has existed since the 1980s. Apple switched macOS to decimal reporting in 2009, which is why a 1 TB drive shows as 1 TB on a Mac but 931 GB on Windows.
How do I calculate file transfer time?
Divide the file size in bytes by the transfer speed in bytes per second. For example, a 10 GB file is 10,000,000,000 bytes. At 100 MB/s, which is 100,000,000 bytes per second, the transfer takes 100 seconds or about 1 minute 40 seconds. At 100 Mbps, first convert to 12.5 MB/s, then divide: 10,000,000,000 ÷ 12,500,000 = 800 seconds or about 13 minutes. Our data rate converter shows theoretical transfer times automatically.
What is the difference between KB and KiB?
KB stands for kilobyte and equals 1,000 bytes in the decimal system. KiB stands for kibibyte and equals 1,024 bytes in the binary system. The difference is 2.4%. While small at the kilobyte level, it compounds to about 7.4% at the gigabyte level and 9.9% at the terabyte level. The IEC introduced kibibyte and the other binary prefixes in 1998 to remove this ambiguity.
Why does my 500 GB cloud storage hold less than 500 GB?
Cloud providers like Google Drive, Dropbox, and iCloud measure storage in decimal gigabytes where 1 GB equals 1,000,000,000 bytes. If you upload files from a Windows PC, Windows reports file sizes in binary gibibytes where 1 GiB equals 1,073,741,824 bytes. A 500 GB cloud plan can hold approximately 465 GiB of Windows-reported files. The space is not missing — the units are simply different.
How do I convert between storage units quickly?
Use our Data Storage Converter. Select your starting unit — for example, TB for a drive label or GiB for a Windows report — and select your target unit. The tool handles both decimal and binary units and shows the exact formula. For quick mental math, remember that binary units are about 2.4% larger at each step, compounding to roughly 7.4% at the GB level and 9.9% at the TB level.
What is data rate and bandwidth?
Data rate is the speed at which data is transferred, measured in bits or bytes per second. Bandwidth is the maximum capacity of a connection to carry data, also measured in bits per second. A 100 Mbps internet connection has a bandwidth of 100 megabits per second and a data rate of approximately 12.5 megabytes per second. Higher bandwidth allows more data to flow simultaneously, which is why multiple users on the same connection slow everyone down.
Real-world conversions
A 1 terabyte hard drive contains 1,000,000,000,000 bytes. Windows divides this by 1,073,741,824 to report capacity in gibibytes, giving 931 GiB. The drive is not defective — Windows is using binary math while the label uses decimal.
An internet plan advertised as 100 megabits per second delivers a theoretical maximum of 12.5 megabytes per second. In practice, protocol overhead and network congestion reduce this to about 9 to 11 MB/s. This is why a 1 GB file takes roughly 90 seconds to download, not 80.
Google Drive, Dropbox, and iCloud measure storage in decimal gigabytes. If you upload files from a Windows PC, Windows reports those files in binary gibibytes. A 500 GB cloud plan holds approximately 465 GiB of Windows-reported files. The missing 35 GB is not a billing error.
A typical 4K movie download is about 50 GB, which equals 50,000 megabytes. At a sustained download speed of 25 MB/s, the transfer takes 2,000 seconds or about 33 minutes. At 100 Mbps, which is 12.5 MB/s, the same file takes about 67 minutes.
Conversion factors are based on international standards. Real-world transfer speeds depend on network conditions, protocol overhead, and hardware limitations.