The progression is -
1KB = 1000 Bytes
1MB = 1000KB
1GB = 1000MB
1TB = 1000GB
That's in common usage.
Technically, it's 1024 instead of 1000 (2 to the 10th power = 1024), so that
1KB = 2ˆ10 Bytes = 1,024 Bytes
1MB = 2ˆ20 Bytes = 1,048,576 Bytes
1GB = 2ˆ30 Bytes = 1,073,741,824 Bytes
1TB = 2ˆ40 Bytes = 1,099,511,627,776 Bytes
But using 1000 as the factor is a whole lot easier, and is usually close enough.