Key difference: One GB constitutes of 1024 MB. One MB constitutes of 1024 KB.

Gigabyte (GB) and Megabyte (MB) are multiples of the unit byte for digital information storage or transmission. Each GB and MB can store different amounts of data. One GB can store 1024 MB of data. One MB can store 1024 KB of data. One KB can store 1024 bytes of data, and one byte has 8 bits of data.

A bit stands for binary digit. It is the basic capacity of information in computing and telecommunications. It is the smallest unit for data storage. Each bit has a value of either 1 or 0.  Eight bits make up a byte. Historically, a byte was the number of bits used to encode a single character of text in a computer. Thus, the byte is the basic addressable element in many computer architectures.

So, since a byte is the smallest addressable element in computer language, let’s see how much data a MB and a GB can hold in terms of bytes.

1 KB = 1024 bytes

1 MB = 1024 KB = 1024^2 bytes = 1048576 bytes

1 GB = 1024 MB = 1024^3 bytes = 1073741824 bytes

Examples of GB storage:

• Seven minutes of HDTV video is approximately 1 GB.
• 114 minutes of uncompressed CD-quality audio is approximately 1 GB.
• A DVD-R can hold about 4.7 GB.
• A dual-layered Blu-ray disc can hold about 50 GB.

Examples of MB storage:

• A 1024×1024 pixel bitmap image with 256 colors
• A 4 megapixel JPEG image with normal compression is about 1 MB in size.
• About 1 minute of 128 kbit/s MP3 compressed music.
• 6 seconds of uncompressed CD audio.
• A typical English book volume in plain text format (500 pages × 2000 characters per page).
• The human genome consists of DNA representing 800 MB of data.

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