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Data Size Converter & Download Time Calculator

Convert between bits, bytes, KB, MB, GB and TB, and estimate how long a download will take

Data Size Converter

Binary: 1 GB = 1024 MB. Decimal: 1 GB = 1000 MB. Bits and bytes always relate by 8 bits = 1 byte.
UnitValue

Download Time Calculator

Enter a file size and your connection speed to estimate the download time. Connection speeds are in bits per second (Mbps), while file sizes are in bytes, so 8 bits = 1 byte is handled for you.

How to use the Data Size Converter

To convert data sizes, enter a value and its unit and the tool shows the equivalent in bytes, KB, MB, GB, and TB. Use the download time calculator to enter a file size and a connection speed and see how long the download will take. It runs in your browser and is free.

  1. Enter a size and unit Type the value you want to convert and select its unit, from bytes up to terabytes.
  2. Choose decimal or binary Pick 1000-based (decimal) or 1024-based (binary) units to match how the size was measured.
  3. Read the conversions See the value expressed in every other data unit at once.
  4. Estimate download time Enter a file size and connection speed to see how long the transfer will take.

About Data Sizes

Digital data is measured in bits and bytes. A bit is the smallest unit (a single 0 or 1), and 8 bits make one byte. Larger units scale up from there: kilobytes (KB), megabytes (MB), gigabytes (GB), and terabytes (TB).

There are two conventions for scaling. The binary (1024-based) system, used by most operating systems, defines 1 KB as 1024 bytes, so 1 GB = 1024 MB. The decimal (1000-based) system, used by storage and network manufacturers, defines 1 KB as 1000 bytes, so 1 GB = 1000 MB. This tool lets you switch between both.

Download speed is where bits and bytes trip people up. Internet speeds are advertised in bits per second (Mbps = megabits per second), while file sizes are in bytes. Because 8 bits = 1 byte, a 1000 MB file over a 100 Mbps connection takes roughly 1000 × 8 ÷ 100 = 80 seconds, not 10.

Frequently Asked Questions

It depends on the convention. In the binary (1024-based) system used by most operating systems, 1 GB = 1024 MB. In the decimal (1000-based) system used on storage device labels, 1 GB = 1000 MB. Use the toggle above to switch between the two.

A bit is a single binary digit (0 or 1). A byte is 8 bits. File sizes are measured in bytes (KB, MB, GB), while network speeds are measured in bits per second (Kbps, Mbps, Gbps). To convert a speed in bits to a transfer rate in bytes, divide by 8.

Because 100 Mbps means 100 megabits per second, and a 100 MB file is 100 megabytes, which equals 800 megabits. At 100 Mbps that takes about 8 seconds in ideal conditions. Real-world overhead, latency, and shared bandwidth usually make it longer.

Manufacturers label drives using the decimal system, where 1 TB = 1,000,000,000,000 bytes. Operating systems report space using the binary system, where 1 TB = 1,099,511,627,776 bytes. That roughly 7% gap is why a "1 TB" drive shows about 931 GB in your file explorer.

Convert the file size to bits (bytes × 8), convert the connection speed to bits per second, then divide file bits by speed bits per second to get seconds. For example, a 1000 MB file is 8,000 megabits; over a 100 Mbps line that is about 80 seconds. This is a best case that ignores network overhead.

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