Bandwidth
Enter the size of the file and the link speed and compute the transfer time, minding bits vs bytes and decimal (SI) vs binary (IEC) units. Includes overhead factor, inverse mode and unit converter.
The size in other units
| Unit | Value | Base |
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The speed in other units
| Unit | Value | Note |
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How it is calculated · bits, bytes and units
1. Network speeds are measured in
bits per second; files in bytes.
1 byte = 8 bits.
2. time (s) = size_in_bits / speed_in_bps,
where size_in_bits = size_in_bytes × 8.
3. Decimal (SI, base 1000): kB=10³ B,
MB=10⁶, GB=10⁹. Binary (IEC, base 1024):
KiB=2¹⁰ B, MiB=2²⁰, GiB=2³⁰.
4. Overhead multiplies time by
(1 + overhead): 10 % overhead takes 10 % longer.
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How it works
The calculator estimates how long a file takes to transfer given its size and the link speed, taking care of the classic bits versus bytes confusion: network speeds are measured in bits per second while files are measured in bytes, with 1 byte = 8 bits. It also distinguishes decimal units (SI: MB = 10⁶ B, GB = 10⁹ B) from binary units (IEC: MiB = 2²⁰ B, GiB = 2³⁰ B), accepts a protocol overhead factor, and has an inverse mode that computes the speed you need to meet a target time.
The base formula is time (s) = size_in_bytes × 8 ÷ speed_in_bps; overhead (TCP/IP headers, retransmissions) multiplies the time by (1 + overhead), or demands proportionally more speed in inverse mode. It also reports the effective throughput and conversion tables for the size and the speed in every unit.
Example: how long does 1 GB take over a 100 Mbps link?
- Size in bits:
1 GB = 10⁹ bytes × 8 = 8 × 10⁹ bits. - Ideal time:
8 × 10⁹ ÷ 100 × 10⁶ = 80 s(1 min 20 s). - With 10 % protocol overhead:
80 × 1.10 = 88 s, for an effective throughput of about 91 Mbps.