Data Size & Transfer Time Calculator: Bits, Bytes, SI & IEC
Convert decimal and binary data units, distinguish MB from MiB and Mbps, and estimate transfer time at a rate you specify.
Enabling local controls…
1. Size and specified rate
Data stays in page memory. Up to 30 integer and 12 fractional digits (value below 10³⁰ selected units); no negative values, commas or exponent. Uses exact decimal fractions.
1 B = 8 bits; 1 MB = 1,000,000 B; 1 MiB = 1,048,576 B; 1 Mbps = 1,000,000 bits/s. Time = size in bits ÷ rate in bits/s, assuming constant effective rate without protocol overhead, latency or disk limits. This is an estimate, not a speed test.
Original unit reference: NIST binary prefixes and bits / bytes
2. Exact conversions
Enter a value or load a sample, then convert.
How to use this tool
Enter a capacity and its exact unit, then optionally add a transfer rate. Review bit/byte conversions, truncated decimal previews and complete exact fractions.
When not to use it
An arithmetic estimate, not a network benchmark. Protocol overhead, compression, latency, disk speed and changing throughput are not measured or included.