Bandwidth & Transfer Calculator
Real transfers rarely reach line rate. 85 to 95% is typical for TCP on a clean path.
The same size in other units
Sizes, link speeds and honest transfer times, with the bits-versus-bytes confusion handled.
Bandwidth and transfer FAQs
Why does my 1 Gbps link only move about 110 MB per second?
Network speeds are quoted in bits per second and file sizes in bytes: eight bits to the byte. A 1 Gbps link therefore tops out at 125 MB/s before protocol overhead, and a healthy TCP transfer typically delivers 85 to 95% of that, which lands near 110 MB/s.
What is the difference between GB and GiB?
GB is decimal, 10^9 bytes; GiB is binary, 2^30 bytes, about 7% larger. Storage vendors and network engineering use decimal, operating systems often display binary. The calculator shows both so the numbers reconcile.
How long does 10 TB take to transfer?
At a full 1 Gbps, about 22 hours; at 100 Mbps, over nine days. This is why large migrations plan bandwidth first, and why shipping physical drives remains rational for very large datasets over slow links.
What efficiency figure should I use?
90% is a reasonable default for TCP on a clean low-latency path. Use lower figures for high-latency links without tuning, many small files, or encrypted tunnels with small MTUs. Line rate, 100%, is a theoretical bound rather than an expectation.
Is anything I enter sent to a server?
No. The math runs in your browser and the page works offline.