AQA · GCSE · Computer Science
Course version: 8525 · Version from Sept 2020
Units of information: mega, 1 MB is 1,000 kilobytes
The prefix mega (symbol M) multiplies a unit by one million, so 1 megabyte (1 MB) is 1,000 kilobytes (1 kB).
Checked against the AQA 8525 specification (opens in a new tab) on .
- Point 9 of 12
Study notes
From the checked teaching notes for this specification point.
The idea
The prefix mega (symbol M) multiplies a unit by one million, so 1 megabyte (1 MB) is 1,000 kilobytes (1 kB). This is a decimal, powers-of-ten relationship: 1 MB = 1,000 kB = 1,000,000 bytes. Work it out by multiplying: to convert megabytes to kilobytes, multiply by 1,000; to go the other way, divide by 1,000. For example, a 4 MB file is 4 × 1,000 = 4,000 kB, and a 2,500 kB file is 2,500 ÷ 1,000 = 2.5 MB. Keep the step direction clear: a megabyte is the larger unit, so there are more kilobytes than megabytes in the same quantity. In a multiple-choice question, check whether the option states the correct factor (1,000, not 1,024) and the correct direction of conversion before choosing.
What earns the marks
- States that 1 MB = 1,000 kB, using the decimal factor of 1,000.
- Explains that mega means one million, so 1 MB = 1,000,000 bytes.
- Converts megabytes to kilobytes by multiplying by 1,000 (e.g. 4 MB = 4,000 kB).
- Converts kilobytes to megabytes by dividing by 1,000 (e.g. 2,500 kB = 2.5 MB).
- Recognises that a megabyte is the larger unit, so a quantity in kB has a larger number than the same quantity in MB.
Common mistakes and how to put them right
Using 1,024 as the factor.
Put it right: The specification uses decimal units, so 1 MB is 1,000 kB, not 1,024 kB.
Multiplying when converting kB to MB.
Put it right: Dividing by 1,000 is correct because kB is the smaller unit.
Confusing the prefix mega with giga.
Put it right: Mega is one million (1,000 kB), whereas giga is one thousand million (1,000 MB).
Assuming a larger number of kB means a larger amount of data.
Put it right: 4,000 kB and 4 MB are the same quantity.
Exam tips
- Write the conversion factor (×1,000 or ÷1,000) beside the question before evaluating the options.
- Check the direction: converting to a smaller unit gives a larger number, so multiply.
- Eliminate any option that uses 1,024, since the specification treats these units as decimal.
- Test each option with a quick example, such as 2 MB = 2,000 kB, to confirm it fits.
Try the lesson
The start of the Units of information: mega, 1 MB is 1,000 kilobytes lesson, made from checked teaching notes for this specification point.
Have a go first
A video file has a size of 3 MB. Using the decimal prefix mega, what is the size of the file in kilobytes?
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of Units of information: mega, 1 MB is 1,000 kilobytes
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge