File size converter — KB, MB, GB, KiB, MiB, GiB
Compare file sizes in decimal units such as MB and GB and binary units such as MiB and GiB. Enter a connection speed for an idealised download-time estimate.
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Binary (1024-based)
Decimal (1000-based)
GB and GiB use different units: 1 GB is 1,000,000,000 bytes; 1 GiB is 1,073,741,824 bytes. A 1 TB drive is about 931 GiB before formatting.
Download time assumes a steady connection at the speed entered. Network overhead and changing speeds can make transfers take longer.
How to use
- Enter the size and its labelled unit. MB and MiB are separate choices. For example, 1 MiB equals 1,048,576 bytes, or 1.048576 MB before display rounding.
- Compare the two tables. They describe the same number of bytes using powers of 1,000 or 1,024.
- Enter a positive speed in Mbps. A 1 GB file at a constant 100 Mbps takes 80 seconds, or 1 minute 20 seconds, before transfer overhead and other delays.
Questions
Why might a 1 TB drive appear as about 931?
1 TB is 1,000,000,000,000 bytes, which is about 931.32 GiB. Some systems label a binary value as GB. Formatting and reserved space can also affect available capacity, so compare the units before interpreting the difference.
What is the difference between Mbps and MB/s?
Mbps means megabits per second; MB/s means megabytes per second. There are eight bits in a byte, so 100 Mbps is 12.5 MB/s before overhead. This calculator’s speed input expects Mbps.
Why does an actual download take longer?
The estimate assumes the full entered speed is available to that file for the whole transfer. Server limits, shared bandwidth, Wi-Fi, pauses and protocol overhead affect real transfers; there is no fixed percentage adjustment that fits every connection.
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