In the decimal SI system, 1 GB equals 1,000 MB. In the binary IEC system, 1 GiB equals 1,024 MiB. For everyday storage estimates, downloads, and data caps, 1 GB is usually treated as 1,000 MB. In operating systems and some technical contexts, the binary relationship of 1,024 may apply instead.

Byte/Bit Converter

Q: What is the difference between bits and bytes?

A bit, written as b, is the smallest unit of digital data and represents a single binary digit, either 0 or 1. A byte, written as B, is made up of 8 bits. File sizes are usually measured in bytes, such as KB, MB, and GB, while network speeds are usually measured in bits per second, such as Kbps, Mbps, and Gbps. To convert between them, multiply bytes by 8 to get bits, or divide bits by 8 to get bytes.

Q: Why does my 1 TB hard drive show as 931 GB in Windows?

Hard drive manufacturers use decimal definitions, where 1 TB equals 1,000,000,000,000 bytes. Windows commonly reports storage using binary units, where 1 TiB equals 1,099,511,627,776 bytes, but often labels the result as GB. Because of this difference in definitions, a drive sold as 1 TB appears smaller in Windows. This is not an error in the drive or the operating system. They are simply using different measurement systems.

Q: How do I convert Mbps to MB/s?

Divide the Mbps value by 8 because 1 byte equals 8 bits. For example, 100 Mbps divided by 8 equals 12.5 MB/s. To convert in the other direction from MB/s to Mbps, multiply by 8. This distinction is important because internet providers usually advertise speeds in megabits per second, while file downloads are often shown in megabytes per second.

Q: What is the difference between KB and KiB?

KB, or kilobyte, in the decimal SI system equals exactly 1,000 bytes. KiB, or kibibyte, in the binary IEC system equals 1,024 bytes. The difference is small at the kilobyte level but grows larger at higher units such as gigabytes and terabytes. The binary terms KiB, MiB, and GiB were introduced to remove confusion, although many systems and users still mix the labels in everyday use.

Q: What is a petabyte and how big is it?

One petabyte, abbreviated PB, equals 1,000 terabytes, 1,000,000 gigabytes, or 10^15 bytes in the decimal system. It is an extremely large amount of data. At that scale, a petabyte can store massive archives, data centers, research datasets, or many tens of thousands of large digital collections.

Q: How much data does streaming use per hour?

Data use depends on the quality level. Standard definition video typically uses about 0.7 GB per hour. High definition 1080p streaming usually uses around 3 to 4 GB per hour. 4K streaming often uses about 7 to 15 GB per hour depending on bitrate and codec. Audio-only streaming generally uses much less, often around 40 to 150 MB per hour depending on quality.

Convert data sizes instantly—bytes (B), KB, MB, GB, TB and more. Enter a value, choose units, and get accurate conversions in seconds. Perfect for file uploads, hosting limits, storage planning, and bandwidth calculations. Free, fast, and easy to use.

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Byte / Bit Converter

The Byte/Bit Converter converts between 14 digital data units: bits, bytes, and six SI-prefixed sizes (kilo through exa) in both bit and byte variants. Enter the value, select the From and To units, and click Convert. Results are displayed immediately.

Digital data units appear in two distinct contexts: storage size (measured in bytes — KB, MB, GB, TB) and data transfer speed (measured in bits per second — Kbps, Mbps, Gbps). These two contexts use the same unit names but different scales, and the bit/byte distinction causes one of the most common points of confusion in computing — particularly when comparing broadband speeds to download speeds.

How to use the Byte/Bit Converter

Enter the data size or speed value to convert.
Select the From unit — the unit your value is currently in (e.g. MB, Gbps, KB).
Select the To unit — the unit you want to convert to.
Click Convert. The result is displayed immediately.
To convert to additional units, change the To dropdown and click Convert again.

Bits vs bytes — the most important distinction

Every confusion in digital unit conversion traces back to one fact: there are 8 bits in 1 byte, and the two are not interchangeable.

File sizes are measured in bytes (B, KB, MB, GB, TB). When your operating system shows a file is 500 MB, it means 500 megabytes = 500,000,000 bytes = 4,000,000,000 bits.
Network speeds and internet connections are measured in bits per second (bps, Kbps, Mbps, Gbps). When a broadband package advertises 100 Mbps, it means 100 megabits per second = 12.5 megabytes per second.
Capital B = bytes. Lowercase b = bits. A 100 Mb/s connection (megabits) is fundamentally different from 100 MB/s (megabytes) — one is 8x faster than the other.

To convert Mbps (megabits per second, a network speed) to MB/s (megabytes per second, a download rate): divide the Mbps value by 8. A 100 Mbps broadband connection downloads files at approximately 100 / 8 = 12.5 MB/s. This is why a 'fast' 100 Mbps broadband connection takes more than a minute to download a 1 GB file — 1,000 MB / 12.5 MB/s = 80 seconds. The download speed table below shows practical download times for common connection speeds.

Decimal (SI) vs binary (IEC) — why storage sizes often look wrong

The second major source of confusion in digital storage is that 'KB', 'MB', and 'GB' are used with two different meanings depending on context:

	Decimal (SI)	Decimal — in bytes	Binary (IEC)	Binary — in bytes
Kilo-	KB (kilobyte)	1,000 B	KiB (kibibyte)	1,024 B
Mega-	MB (megabyte)	1,000,000 B	MiB (mebibyte)	1,048,576 B
Giga-	GB (gigabyte)	1,000,000,000 B	GiB (gibibyte)	1,073,741,824 B
Tera-	TB (terabyte)	1,000,000,000,000 B	TiB (tebibyte)	1,099,511,627,776 B
Peta-	PB (petabyte)	10^15 B	PiB (pebibyte)	2^50 B = 1,125,899,906,842,624 B
Exa-	EB (exabyte)	10^18 B	EiB (exbibyte)	2^60 B = 1,152,921,504,606,846,976 B

Hard drive manufacturers use decimal definitions (1 GB = 1,000,000,000 bytes) because it makes the drive appear larger. Operating systems traditionally use binary definitions (1 GiB = 1,073,741,824 bytes) when displaying storage capacity. This is why a hard drive sold as '1 TB' shows as approximately '931 GB' in Windows or macOS — the drive genuinely contains 1,000,000,000,000 bytes, but the OS is reporting it in binary gibibytes (931 GiB). Neither is wrong — they are using different definitions of the same prefix. The IEC introduced the KiB, MiB, GiB naming standard in 1998 to eliminate this ambiguity, but informal usage of KB/MB/GB for both definitions persists.

All 14 units — values and contexts

Unit	In bytes	Typical context
Bit-based units
Bit (b)	0.125 B (1/8 byte)	The smallest unit of digital data — a binary 0 or 1. Network speeds, wireless standards, and internet connections are measured in bits per second (bps, Kbps, Mbps, Gbps). File sizes are measured in bytes, not bits.
Kilobit (Kb)	125 B (decimal: 1,000 bits)	Low-bandwidth connections: old dial-up modem speeds (56 Kbps), some IoT sensor data rates, telegraph and early digital communication speeds.
Megabit (Mb)	125,000 B	Broadband speed ratings. UK average broadband is approximately 60–100 Mbps. A 100 Mbps connection transfers approximately 12.5 MB of data per second. Wireless standards (Wi-Fi 6 up to ~9.6 Gbps theoretical).
Gigabit (Gb)	125,000,000 B	Gigabit Ethernet (1 Gbps = 125 MB/s), fiber broadband, data center interconnects. A full 1 Gbps connection downloads approximately 125 MB per second.
Terabit (Tb)	125,000,000,000 B	Backbone network capacity, submarine cable capacity, data center aggregation links. Modern transoceanic cables carry hundreds of terabits per second in aggregate.
Petabit (Pb)	125,000,000,000,000 B	Internet backbone aggregate capacity. Total global internet traffic is measured in petabits per month. Rarely encountered in individual system specifications.
Exabit (Eb)	125,000,000,000,000,000 B	Total global data volumes. Global internet traffic is estimated to reach exabit-per-year scale. Rarely used in practical specifications.
Byte-based units (decimal: 1 KB = 1,000 B)
Byte (B)	1 B	The basic unit of digital storage. One ASCII character = 1 byte. A small plain-text email is typically 5–20 KB. Individual pixel colour data is commonly 3–4 bytes.
Kilobyte (KB)	1,000 B	Small files: plain text documents, configuration files, small images (icon files), web page HTML. A typical webpage HTML file is 10–100 KB.
Megabyte (MB)	1,000,000 B	Documents, photos, audio files, mobile app sizes. A typical JPEG photo is 1–5 MB. A minute of MP3 audio at 128 kbps is approximately 1 MB. A typical smartphone app is 20–200 MB.
Gigabyte (GB)	1,000,000,000 B	Video files, game installations, phone and laptop storage. A minute of 1080p video is approximately 0.5–2 GB depending on codec and bitrate. Modern AAA games require 50–150 GB. USB drives and SD cards are commonly 16 GB–2 TB.
Terabyte (TB)	1,000,000,000,000 B	Large hard drives, NAS storage, server volumes, backup archives. Consumer hard drives range from 1–20 TB. A raw 4K video production day generates 1–10 TB of footage.
Petabyte (PB)	10^15 B	Cloud storage totals, large-scale data warehouses, entire web archive snapshots. The Internet Archive stores approximately 100 PB. Hyperscale cloud providers manage exabytes of total storage.
Exabyte (EB)	10^18 B	Global data scale. An exabyte is 1,000 petabytes. Global data creation is projected to reach zettabytes (1,000 EB) annually in the coming decade. Encountered in global data statistics.

Download speed reference — Mbps to MB/s and file download times

The table below converts common broadband speeds from Mbps (network speed) to MB/s (actual download rate) and shows approximate download times for a 1 GB and 1 hour of 1080p video (approximately 4 GB). These are theoretical maximums — real-world performance varies with server capacity, routing, and overhead:

Connection speed	In MB/s	1 GB file download time	1 hour 1080p video (approx 4 GB)
10 Mbps	1.25 MB/s	~13 minutes	~53 minutes
50 Mbps	6.25 MB/s	~2.7 minutes	~11 minutes
100 Mbps	12.5 MB/s	~1.3 minutes	~5.3 minutes
500 Mbps	62.5 MB/s	~16 seconds	~64 seconds
1 Gbps	125 MB/s	~8 seconds	~32 seconds

Common use cases

Server and web hosting configuration

Web server configurations specify upload limits and memory sizes in various units. PHP's upload_max_filesize and post_max_size are set in M (megabytes) or G (gigabytes). Nginx and Apache use bytes, kilobytes, or megabytes for body size limits. A PHP config of upload_max_filesize = 8M means 8 MB = 8,000,000 bytes. When a form validation error says 'maximum file size exceeded', check whether the limit is in MB or MiB — many systems use the binary definition internally.

Broadband and streaming

ISP speeds are advertised in Mbps (megabits per second). Streaming services state their video quality bitrates in Mbps. To compare: Netflix recommends 5 Mbps for HD (1080p) streaming = 0.625 MB/s = approximately 2.25 GB per hour. A 4K stream requires 15–25 Mbps = 1.875–3.125 MB/s = 6.75–11.25 GB per hour. Monthly data caps stated in GB are in gigabytes (byte-based), while speed limits are in Mbps (bit-based).

Storage planning

When planning backup storage or NAS capacity, note that usable space is always less than stated capacity. A 4 TB drive contains 4,000,000,000,000 bytes = approximately 3,637 GiB as shown by most operating systems. RAID configurations reduce usable capacity further: RAID 1 (mirroring) halves the total; RAID 5 loses one drive's worth of capacity for parity. Always calculate required storage with a buffer of at least 20% beyond estimated needs.

Usage limits

Account type	Daily conversions
Guest	25 per day
Registered	100 per day

Related tools

Decimal to Hex — convert decimal integers to hexadecimal notation. Used alongside byte conversion in low-level programming and memory address calculations.
Hex to Binary — convert hexadecimal values to binary. Useful for understanding byte-level data representation.
Percentage Calculator — calculate what percentage of a storage quota is used, or what percentage of bandwidth is consumed.

Frequently asked questions

What is the difference between bits and bytes?

A bit (b) is the smallest unit of digital data — a single binary digit, either 0 or 1. A byte (B) is 8 bits. File sizes are measured in bytes (KB, MB, GB). Network speeds are measured in bits per second (Kbps, Mbps, Gbps). To convert between bytes and bits: bytes x 8 = bits; bits / 8 = bytes. A 500 MB file contains 500,000,000 bytes = 4,000,000,000 bits. A 100 Mbps connection transfers 100,000,000 bits per second = 12,500,000 bytes per second = 12.5 MB/s.

Why does my 1 TB hard drive show as 931 GB in Windows?

Hard drive manufacturers use decimal definitions: 1 TB = 1,000,000,000,000 bytes. Windows reports storage in binary units (gibibytes, GiB): 1 TiB = 1,099,511,627,776 bytes. So 1,000,000,000,000 bytes / 1,099,511,627,776 bytes per GiB = approximately 909 GiB, displayed as '909 GB'. This is not a manufacturer error or an OS error — they are using different but equally valid definitions of the prefix. The drive contains the advertised number of bytes; the OS is displaying in GiB. macOS switched to decimal units in macOS 10.6, so a 1 TB drive correctly shows as approximately 1 TB in macOS.

How do I convert Mbps to MB/s?

Divide the Mbps value by 8. 1 megabyte = 8 megabits. Example: 100 Mbps / 8 = 12.5 MB/s. This is the actual download speed for a 100 Mbps connection. A 1 GB (1,000 MB) file would take 1,000 / 12.5 = 80 seconds on a 100 Mbps connection under ideal conditions. To convert MB/s to Mbps: multiply by 8. Example: 50 MB/s x 8 = 400 Mbps.

What is the difference between KB and KiB?

KB (kilobyte) in the decimal (SI) system = 1,000 bytes exactly. KiB (kibibyte) in the binary (IEC) system = 1,024 bytes = 2^10 bytes. The difference is 2.4% at the kilo level, but grows at higher prefixes: 1 GB (decimal) = 1,000,000,000 bytes; 1 GiB (binary) = 1,073,741,824 bytes — a 7.4% difference. The IEC kibibyte/mebibyte/gibibyte naming was introduced in 1998 to remove ambiguity. In practice, most informal usage of KB and GB means the decimal SI value; operating systems often use the binary value but display it with the SI abbreviation.

How many MB is 1 GB?

In the decimal (SI) system: 1 GB = 1,000 MB = 1,000,000 KB = 1,000,000,000 bytes. In the binary (IEC) system: 1 GiB = 1,024 MiB = 1,048,576 KiB = 1,073,741,824 bytes. For everyday purposes (storage estimates, file size comparisons, data cap calculations): treat 1 GB = 1,000 MB. For OS disk usage displays and some technical applications, 1 GiB = 1,024 MiB applies.

What is a petabyte and how big is it?

1 petabyte (PB) = 1,000 terabytes = 1,000,000 gigabytes = 10^15 bytes. For scale: the human brain is estimated to have a storage capacity of roughly 2.5 petabytes (though this analogy is imprecise). The complete English Wikipedia (text, without media) is approximately 21 GB — you could fit roughly 47,000 complete Wikipedia’s in a petabyte. The entire Library of Congress print collection is estimated at approximately 10–15 terabytes, so 1 petabyte holds roughly 70–100 Library of Congress equivalents.

How much data does streaming use per hour?

Data consumption depends on video quality and streaming service. Standard definition (480p): approximately 0.7 GB per hour. High definition (1080p): approximately 3–4 GB per hour. 4K Ultra HD: approximately 7–15 GB per hour depending on codec and bitrate. Audio-only streaming: approximately 40–150 MB per hour depending on quality (Spotify high quality uses approximately 144 MB per hour). Monthly broadband data caps of 100–200 GB support approximately 25–50 hours of HD streaming.

Is the Byte/Bit Converter free?

Yes. The converter is free within the daily usage limits shown above. Guest users can perform 25 conversions per day without creating an account. Registering a free ToolsPiNG account increases the daily limit to 100 conversions per day.