Same word, two sizes: 1000 or 1024
"KB to MB" has two right answers because there are two standards. Decimal (SI) steps by 1,000; binary (IEC) steps by 1,024. Storage capacity, network speeds and marketing specs use decimal; RAM, operating-system internals and most programming use binary.
The same 1,000 KB reads as a full 1 MB in decimal but only 0.954 MiB in binary — the 1,024 divisor makes each binary unit slightly bigger, so fewer of them fit.
The two conversions
For decimal there is a shortcut: move the decimal point three places left, so 4,500 KB is 4.5 MB. The gap between the two conventions grows as the numbers do — about 2.4% at MB, but a "1 TB" drive shows as ~931 GiB, roughly 7% smaller.
Common values, both ways
| KB | MB (decimal, ÷1000) | MiB (binary, ÷1024) |
|---|---|---|
| 100 | 0.1 | 0.0954 |
| 500 | 0.5 | 0.4768 |
| 1,000 | 1.0 | 0.9537 |
| 1,024 | 1.024 | 1.0 |
| 5,000 | 5.0 | 4.883 |
| 10,000 | 10.0 | 9.537 |
| 100,000 | 100.0 | 95.37 |
A separate trap: internet speed is quoted in megabits (Mb/s), not megabytes. 100 Mbps is only 12.5 MB/s — divide by 8.
Common questions
How many KB are in 1 MB?
In the decimal standard, 1 MB is 1,000 KB. In the binary convention it is 1,024 (written properly as 1 MiB = 1,024 KiB). Which one is correct depends on the context you are in.
Is 1024 KB equal to 1 MB?
Only in the binary convention, where 1 MiB equals 1,024 KiB. Under the official decimal (SI) definition, 1 MB is exactly 1,000 KB. The two answers differ by about 2.4%.
Why does my hard drive show less space than the box says?
Drive makers count in decimal, so a "1 TB" drive holds 1,000,000,000,000 bytes. Windows divides that by 1,024 three times and labels the result "GB," showing about 931. Nothing is missing; the two sides just count differently.
