File Size Converter
Convert between bytes, kilobytes, megabytes and gigabytes.
Your figures
Result
How to use this tool
- Enter your figures in the fields on the left.
- Results update instantly as you type — there is no button to press.
- Change any input to see how sensitive the answer is to it.
This uses binary units, where 1 KB is 1024 bytes — the convention operating systems and upload forms use. Storage manufacturers use decimal units where 1 KB is 1000 bytes, which is why a "1 TB" drive shows as about 931 GB.
How it works
The calculation runs in your browser as you type — there is no submit button and nothing is sent anywhere. Change any figure and the results update immediately, which makes it easy to see how sensitive the answer is to each input.
Every formula used here is standard and documented in the questions below. Where a result depends on an assumption, the assumption is stated rather than buried.
Frequently asked questions
Is a kilobyte 1000 or 1024 bytes?
Both conventions exist. Operating systems and upload limits generally use 1024; storage manufacturers use 1000. This converter uses 1024.
Why does my 1 TB drive show 931 GB?
The manufacturer counted 1 TB as a trillion bytes; your operating system divides by 1024 three times, giving about 931 GB. No storage is missing.
What are MiB and GiB?
Explicit binary units — mebibyte and gibibyte — introduced to remove exactly this ambiguity. 1 MiB is precisely 1,048,576 bytes.
Is this calculator free?
Yes, with no account, no limits and no data collection. It runs entirely in your browser.
Should I rely on this for a financial or medical decision?
No. It is a planning estimate built on standard formulas and stated assumptions. For decisions that matter, speak to a qualified professional who can account for your full circumstances.
Is this calculator accurate?
The arithmetic is exact — it uses the standard formula, shown in the questions above. What limits accuracy is the assumptions: the figures you enter, and factors the formula does not model such as fees, taxes and rule changes. Treat the result as a well-founded estimate rather than a quotation.
Do I need to sign up or download anything?
No. It runs in your browser, updates as you type, and stores nothing. There is no account, no download, and no limit on how many times you use it.
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Your files stay on your device. This tool runs entirely in your browser. No file is uploaded, transmitted, or stored. You can verify this by opening your browser's Network tab while using the tool.
Disclaimer. This calculator provides estimates based on standard formulas and the assumptions stated above. It is not financial, medical, tax or legal advice. For decisions that matter, consult a qualified professional. See our full disclaimer.