MB to KB Converter

A thousand kilobytes, give or take twenty-four

Decimal says 1,000 kilobytes to the megabyte; binary says 1,024. Both are in use, and the switch below picks between them.

1 MB = 1,000 KB (decimal) or 1,024 KB (binary)

This conversion mostly matters for upload limits and web performance budgets, where a target stated in MB has to be checked against file sizes listed in KB.

The megabyte

A million bytes decimal, or 1,048,576 binary — the difference is about 4.9 %. A megabyte holds roughly a minute of compressed music or a medium-sized photograph.

Which convention applies depends on who is counting. Storage makers use decimal; Windows reports binary while calling it MB; macOS and Linux generally report decimal.

The kilobyte

A thousand bytes under the decimal convention, or 1,024 under the binary one. The ambiguity dates from the early days of computing, when memory came in powers of two and 1,024 was close enough to a thousand that people called it a kilobyte.

The standards bodies later split the two: KB for 1,000 bytes and KiB for 1,024. In practice almost nobody writes KiB, so the meaning depends on context.

The working, step by step

Every line updates with whatever you type above. The point is the method, which is the same for any pair of units in this family.

Copy the working

The same quantity, two different numbers

One physical amount, read off two scales. The tick marks do not line up, and the gap between them is the conversion factor made visible.

How much is that?

A number is easier to judge next to something familiar.

Your turn

Reading a method and being able to use it are different things. Answer within half a per cent and it counts as correct.

How to use this converter

1. Type into either box. The other side updates as you go; there is no button to press.
2. Swap the direction with the button between the boxes, carrying your value across.
3. Set the decimals if the default is more or less precision than you need.
4. Copy the answer with its unit, ready to paste.
5. Use the shortcut buttons for the values that come up most often.
6. Share the result. The address bar tracks what you type, so the link you copy opens on the same number.

Common uses and tips

Where these conversions come up

• Buying storage. A drive sold as 1 TB shows up as 931 GB in Windows. Nothing is missing; the two are counting in different bases.
• Upload limits. Attachment and upload caps are stated in MB, and file managers report sizes in MB too — but not always the same MB.
• Mobile data. Allowances are in GB, app usage is reported in MB.
• Broadband speed. Sold in megabits, downloaded in megabytes, eight times apart.
• Backups and disk planning, where a few per cent of convention error compounds into real numbers at terabyte scale.

The big one: decimal against binary

There are two conventions, and both are in daily use.

• Decimal. A kilobyte is 1,000 bytes, a megabyte 1,000,000, a gigabyte 1,000,000,000. This is what the SI prefixes actually mean, and what storage manufacturers use.
• Binary. A kilobyte is 1,024 bytes, a megabyte 1,048,576, a gigabyte 1,073,741,824. Memory is built in powers of two, so this is what operating systems grew up using.

The gap widens with every step: 2.4 % at kilobytes, 4.9 % at megabytes, 7.4 % at gigabytes, 9.95 % at terabytes. That is why a 1 TB drive reports as 931 GB — a difference of 69 GB that looks like missing capacity and is not.

The standards bodies resolved this in 1998 by inventing separate binary prefixes: KiB, MiB, GiB and TiB for the powers of two, leaving KB, MB, GB and TB for the powers of ten. Linux mostly adopted them. Windows did not, and still labels binary quantities with decimal names.

Bits and bytes

Eight bits make a byte. Capitalisation is the only thing distinguishing them: Mb is megabits, MB is megabytes.

Network speeds are sold in bits and files are measured in bytes, which is why a 100 Mbps connection downloads at about 12.5 MB/s. The connection is not underperforming; the units differ by a factor of eight.

Tips worth knowing

• Bitrates are always decimal. A kilobit per second is 1,000 bits per second, never 1,024. The binary ambiguity affects storage, not speed.
• RAM is always binary. An 8 GB memory module is 8 GiB — 8,589,934,592 bytes — because memory is addressed in powers of two.
• Check which convention a figure uses before comparing two of them. Comparing a decimal number with a binary one is where the confusion starts.

Values people look up most

Each one opens the converter with the number already in it.

• 0.5 MB to KB
• 1 MB to KB
• 2 MB to KB
• 3 MB to KB
• 5 MB to KB
• 8 MB to KB
• 10 MB to KB
• 15 MB to KB
• 20 MB to KB
• 25 MB to KB
• 30 MB to KB
• 50 MB to KB
• 75 MB to KB
• 100 MB to KB
• 200 MB to KB
• 500 MB to KB
• 1,000 MB to KB

Quick reference

Decimal convention: 1,000 KB to the MB.

Megabytes	Kilobytes
0.5 MB	500 KB
1 MB	1,000 KB
2 MB	2,000 KB
5 MB	5,000 KB
10 MB	10,000 KB
20 MB	20,000 KB
50 MB	50,000 KB
100 MB	100,000 KB
500 MB	500,000 KB
1,000 MB	1,000,000 KB

Questions people ask

How many KB in a MB?

1,000 decimal, 1,024 binary.

What is 5 MB in KB?

5,000 KB decimal, or 5,120 KB binary.

Which one do email attachment limits use?

Usually binary, since mail servers count in powers of two, but it varies. Leave a margin.