GCSE Computer Science J277 - Mr Brown
Smallest to largest, left to right.
Enter an amount, choose its unit, then convert!
Enter a file size in bytes. The tool picks the unit that gives the most sensible number to work with.
Every unit of data storage is built from the one before it. Learn this order!
| Unit | What it is | Size |
|---|---|---|
| bit | A single binary digit — a 0 or a 1 | 1 bit |
| nibble | Half a byte | 4 bits |
| byte | The smallest unit normally used to store a character | 8 bits (2 nibbles) |
| KB | Kilobyte | 1,000 bytes |
| MB | Megabyte | 1,000 KB (1,000,000 bytes) |
| GB | Gigabyte | 1,000 MB (1,000,000,000 bytes) |
| TB | Terabyte | 1,000 GB (1,000,000,000,000 bytes) |
We always convert using 1000 between KB, MB, GB and TB as we are not allowed a calculator in the exam.
Example 1 — bigger to smaller: Convert 2.5 GB to MB. GB is bigger than MB, so multiply.
2.5 GB × 1000 = 2,500 MB
Example 2 — smaller to bigger: Convert 3,000,000 bytes to MB. bytes is smaller than MB, so divide.
3,000,000 bytes ÷ 1,000,000 = 3 MB
For more than one step (e.g. KB to TB), just apply ÷1000 or ×1000 once for each step on the Unit Ladder.
The "best" unit is the largest one that still gives a number of 1 or more — that avoids both a long string of digits and a number that's mostly zeros.
Worked example: a photo is 4,500,000 bytes.
| Unit | Value | Verdict |
|---|---|---|
| KB | 4,500 KB | Too many digits — unwieldy |
| MB | 4.5 MB | ✅ Best — easy to read and compare |
| GB | 0.0045 GB | Too small — mostly zeros |
Try your own file sizes in the Playground's "Pick the Best Unit" tool.