Bits & Bytes

💡 The bit

Deep down a computer uses switches that are either OFF or ON, written 0 or 1. One such switch is a bit — the smallest piece of information.

📦 8 bits = a byte

Eight bits grouped together make a byte. One byte can store a single letter, like the 'A' in your name. Your full name is just a few bytes.

🪜 The size ladder

About 1000 bytes = 1 kilobyte (KB). About 1000 KB = 1 megabyte (MB). About 1000 MB = 1 gigabyte (GB). About 1000 GB = 1 terabyte (TB). Each step is roughly a thousand times bigger.

📱 Everyday sizes

A text message is a few bytes. A photo is a few MB. A music track is a few MB. A long HD video or a big app is hundreds of MB to several GB. A phone might store 128 GB.

📶 Speed vs size

Internet speed is measured in megabits per second (Mbps, small b). File size is in megabytes (MB, big B). Since 8 bits = 1 byte, a 16 Mbps link downloads about 2 MB each second — handy to know when buying a data bundle.

Key points

• Deep down a computer uses switches: off or on, 0 or 1. That's a bit.
• Eight bits make a byte, which can store one letter.
• About a thousand bytes is a kilobyte; a thousand KB is a megabyte.
• A thousand MB is a gigabyte; a thousand GB is a terabyte.
• A photo is a few MB; a long video is hundreds of MB to several GB.
• Internet speed is in megabits (small b); files are in megabytes (big B).
• Eight bits per byte, so a 16 Mbps link does about 2 MB a second. Good for bundles!

Try it for real: Size and speed

• Check the size of a photo and a video on your device (in MB or GB).
• Find your phone's total storage and how much is free.
• With a grown-up, note your data bundle speed (Mbps) and estimate the MB per second.