Data Size Converter
Convert between bits, bytes, kilobytes, megabytes, gigabytes, terabytes and more.
Bits, bytes, and the binary number system
A bit (binary digit) is the smallest unit of digital information — it can only be 0 or 1. Everything stored or transmitted digitally is ultimately a sequence of bits. Eight bits form one byte, which can represent 256 different values (2⁸). A single ASCII character occupies one byte; a Unicode character can take 1–4 bytes depending on encoding.
All conversions on this page use the bit as the base unit. Every larger unit is a power-of-two multiple: 1 KB = 2¹⁰ bytes = 1,024 bytes = 8,192 bits. This binary (base-2) progression is inherent to how computers address memory.
Binary (IEC) vs. decimal (SI) prefixes: the source of endless confusion
The most significant source of confusion in data sizing is that the same prefix — "kilo", "mega", "giga" — means two different things depending on who is using it.
| Common name | Binary (IEC) — used by OSes | Decimal (SI) — used by drive makers | Difference |
|---|---|---|---|
| Kilobyte | 1 KB = 1,024 bytes (KiB) | 1 KB = 1,000 bytes | 2.4% |
| Megabyte | 1 MB = 1,048,576 bytes (MiB) | 1 MB = 1,000,000 bytes | 4.9% |
| Gigabyte | 1 GB = 1,073,741,824 bytes (GiB) | 1 GB = 1,000,000,000 bytes | 7.4% |
| Terabyte | 1 TB = 1,099,511,627,776 bytes (TiB) | 1 TB = 1,000,000,000,000 bytes | 10.0% |
This is why a 1 TB hard drive (1,000,000,000,000 bytes by the manufacturer's definition) shows as approximately 931 GB in Windows or Linux — those operating systems report in binary gigabytes (GiB), each of which is 1,073,741,824 bytes. The drive is not "missing" storage; the two systems simply count differently.
This converter uses binary (IEC) prefixes throughout, consistent with how operating systems report file sizes and memory capacities.
Bits vs. bytes: when each is used
Bytes (capital B) measure storage: file sizes, RAM, disk capacity. Bits (lowercase b) measure transfer speed: internet connection speed, network throughput, video bitrate. Confusing the two is extremely common and leads to misunderstanding advertised internet speeds.
Internet plan: 100 Mbps = 100 megabits per second
Download speed in bytes: 100 ÷ 8 = 12.5 MB/s
A 1 GB file at 100 Mbps:
1,024 MB ÷ 12.5 MB/s = ~82 seconds to download
Video streaming (4K HDR): ~25 Mbps = ~3.1 MB/s per streamCommon real-world uses
Reference: full binary size table
1 byte = 8 bits
1 KB = 1,024 bytes = 8,192 bits
1 MB = 1,048,576 bytes = 8,388,608 bits
1 GB = 1,073,741,824 bytes
1 TB = 1,099,511,627,776 bytes
1 PB = 1,125,899,906,842,624 bytes
Typical file sizes:
Plain text email: ~5 KB
MP3 song (3 min): ~3.5 MB
JPEG photo: ~3–8 MB
4K movie (2hr): ~50–100 GBTips for avoiding data size mistakes
- Capital B = Bytes; lowercase b = bits. 100 Mbps is megabits per second. 100 MBps is megabytes per second — eight times larger. Check the capitalisation before comparing any two specs.
- Advertised drive capacity is in decimal GB. A "2 TB" SSD holds 2,000,000,000,000 bytes. Your OS will display it as ≈ 1.82 TiB (binary terabytes). Neither number is wrong — they use different counting systems.
- Internet speed ÷ 8 = download rate. A 500 Mbps connection delivers roughly 62.5 MB/s of usable download speed — not 500 MB/s. Overhead from protocols (TCP/IP headers, SSL) typically reduces real-world throughput by another 5–15%.
- Streaming bitrate and file size are directly linked. A video encoded at 10 Mbps generates 10 megabits per second = 1.25 MB/s = 75 MB per minute = 4.5 GB per hour. Knowing this lets you estimate storage before recording or downloading.
Frequently asked questions
How many megabytes are in a gigabyte?
Using the decimal standard, 1 GB equals 1,000 MB. Using the binary standard (gibibytes), 1 GiB equals 1,024 MiB. Storage is usually sold in decimal units.
What is the difference between a bit and a byte?
A byte is 8 bits. File sizes are normally measured in bytes (KB, MB, GB), while network and connection speeds are usually measured in bits (Mbps).
Why does my hard drive show less space than advertised?
Manufacturers count storage in decimal (1 TB = 1,000,000,000,000 bytes), but operating systems often display it in binary, so a 1 TB drive shows as about 931 GiB.
How do I convert megabits to megabytes?
Divide megabits by 8. A 100 Mbps connection transfers about 12.5 MB per second.
Uses binary prefixes: 1 KB = 1,024 bytes = 8,192 bits. Click any tile to use that value as new input.