Converting Between Units

Converting between units means changing a value from one data unit to another while keeping the same amount of data. The number changes because the unit changes.

Bits and bytes

A bit is one binary digit and a byte is 8 bits. To convert bits to bytes, divide by 8. To convert bytes to bits, multiply by 8. For example, a short sensor reading is 640 bits, which is 640 ÷ 8 = 80 bytes, and 80 bytes is 80 × 8 = 640 bits.

Larger and smaller units

From bytes upwards, each unit is 1,000 times the one before: 1 kilobyte is 1,000 bytes, 1 megabyte is 1,000 kilobytes, 1 gigabyte is 1,000 megabytes, 1 terabyte is 1,000 gigabytes and 1 petabyte is 1,000 terabytes. To move to a larger unit, divide by 1,000 for each step. To move to a smaller unit, multiply by 1,000 for each step. So 5,600,000 bytes is 5,600 KB, then 5.6 MB. Going the other way, 3.5 TB is 3,500 GB, then 3,500,000 MB.

File sizes and comparisons

The standard formulas for text, image and sound files give a size in bits. Convert that answer by dividing by 8 to get bytes, then divide by 1,000 for each step up. Suppose a calculation gives 4,800,000 bits. That is 600,000 bytes, 600 KB and 0.6 MB. A calculation might be requested in bits, bytes, kilobytes, megabytes or gigabytes, so always finish by converting your answer to the unit asked for. To compare capacities or file sizes, convert every value to the same unit before comparing. A storage device has a fixed capacity: a 6 GB memory card holds 6,000 MB, so it has room for a 5,500 MB video collection but not for a 7,000 MB video collection.