Data Size Converter: MB, GB, TB, GiB and Download Time
Convert data sizes between bits, bytes, kB, MB, GB, TB, PB and KiB, MiB, GiB, TiB, PiB, and see how long a file takes to download at your connection speed.
Things to keep in mind:
- The download time is theoretical: protocol overhead, server speed, Wi-Fi losses and congestion usually make the real time longer.
- Some programs and Windows show binary (1,024-based) values as "KB, MB, GB"; check which family is used before comparing numbers.
- File-system overhead (cluster size, compression) is not considered.
Calculator
Result
Enter the values and press Calculate to see the result here.
About this tool
This tool converts data amounts between two families of units and estimates the download time at a given connection speed.
There are two families:
- SI (decimal) prefixes: 1 kB = 1,000 B, 1 MB = 1,000,000 B, 1 GB = 10⁹ B. Disk makers, network speeds and most product boxes use these units.
- IEC (binary) prefixes: 1 KiB = 1,024 B, 1 MiB = 1,024² B, 1 GiB = 1,024³ B = 1,073,741,824 B. Operating systems and memory (RAM) sizes are mostly computed with these, although Windows labels them "KB, MB, GB".
Also, 1 byte = 8 bits; internet speeds are given in bits (Mbit/s) and file sizes in bytes (MB).
Formulas: result = value × (bits per source unit) ÷ (bits per target unit); download time (s) = total bits ÷ (speed in Mbit/s × 1,000,000).
Example: 1 GB = 10⁹ B ÷ 1,048,576 ≈ 953.67431641 MiB, which is why a "1 TB" drive shows up as about 931 GiB. A 4.7 GB file is 4.7 × 8 × 10⁹ = 37.6 × 10⁹ bits; at 100 Mbit/s it takes 37.6 × 10⁹ ÷ 10⁸ = 376 seconds (6 minutes 16 seconds).
The prefixes follow IEC 80000-13 and the SI prefix definitions.
How to use
- Enter the amount of data.
- Choose the units under From unit and To unit; mind the SI (kB, MB, GB) and IEC (KiB, MiB, GiB) families.
- To see the download time, enter your connection speed in Mbit/s (default 100).
- Select Calculate.
Notes
The main result is rounded half-up (HALF_UP) to 8 decimals, the unit equivalents to 6, the conversion factor to 10, and the download time in seconds and minutes to 2 decimals. The hours/minutes/seconds breakdown uses the time rounded up to whole seconds.
Frequently asked questions
By the SI definition 1 GB = 1,000 MB. The 1,024 relation applies to the binary units: 1 GiB = 1,024 MiB. Because the two meanings get mixed up, the tool lists both families separately.
The maker uses 1 TB = 10¹² B; the operating system divides by 1,024⁴: 10¹² ÷ 1,099,511,627,776 ≈ 0.909 TiB ≈ 931 GiB. Nothing is lost; only the unit differs.
1 GB = 8,000 Mbit, and 8,000 ÷ 100 = 80 seconds (theoretical). The real time is a little longer due to network overhead.
Mbps (Mbit/s) is megabits per second, MB/s megabytes per second. Since 1 MB/s = 8 Mbit/s, a 100 Mbit/s line downloads at most 12.5 MB/s.
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