Data Storage Converter
Convert digital storage between decimal units (KB, MB, GB) and binary units (KiB, MiB, GiB), which is why your drive looks smaller than the box said.
How it works
There are two systems, and mixing them is the source of nearly every storage confusion. Decimal units step in powers of 1,000: a kilobyte is 1,000 bytes, a megabyte 1,000,000. Binary units step in powers of 1,024: a kibibyte (KiB) is 1,024 bytes, a mebibyte (MiB) 1,048,576.
Drive manufacturers sell in decimal units; operating systems have traditionally reported in binary ones while labelling them with decimal names. A 1 TB drive holds 1,000,000,000,000 bytes, which Windows reports as about 931 GB — nothing is missing, the two are just counting differently.
Both systems are offered here separately rather than averaged, because the difference reaches roughly 10% by the terabyte and grows with each step up.
The formula
GB → MB
MB = GB × 1,000
MB → GB
GB = MB ÷ 1,000
Any pair in this family
result = value × (factor of source ÷ factor of target)
Every unit is defined against the byte, so any combination converts in one step.
Worked examples
| Scenario | Working | Result |
|---|---|---|
| 1 GB to MB (decimal) | 1 × 1000 | 1,000 MB |
| 1 GiB to MiB (binary) | 1 × 1024 | 1,024 MiB |
| A 1 TB drive as the OS sees it | 10¹² ÷ 1024³ | ≈ 931 GiB |
When you'd use it
- Working out why a new drive shows less space than advertised
- Converting a file or backup size
- Estimating bandwidth or transfer volumes
- Reading a spec that mixes MB and MiB
Common questions
Why does my 1 TB drive show as 931 GB?
The manufacturer counts in decimal — 1 TB is a trillion bytes. The operating system divides by 1,024 three times, giving about 931. No space is lost; the two are simply using different definitions of the same prefix.
What is the difference between MB and MiB?
A megabyte (MB) is 1,000,000 bytes; a mebibyte (MiB) is 1,048,576 bytes, about 4.9% more. The binary units KiB, MiB and GiB were introduced specifically to remove this ambiguity, though the older names remain common.
Are megabits and megabytes the same?
No — there are 8 bits in a byte. Internet speeds are usually quoted in megabits per second, so a 100 Mbps connection downloads at about 12.5 megabytes per second. That factor of eight surprises people regularly.
Is anything I enter sent anywhere?
No. Every conversion runs in your browser, so nothing you type is uploaded, logged or stored. There is no account and no record of what you converted.