Bandwidth and Transfer Time Calculator

Estimate file transfer duration with explicit file units and useful-throughput efficiency.

Local calculation · inputs are not sent to a server.

Result

Calculating the example…

How it works

Time in seconds = file bytes × 8 ÷ effective bits per second. Effective rate equals the selected Mbps × 1,000,000 × efficiency fraction. The result is a constant-rate estimate.

Worked example

5 decimal GB at 100 Mbps with 90% useful throughput takes about 444.44 seconds, or 7.41 minutes. At 100% it would take 400 seconds.

Inputs, edge cases & common mistakes

Bits and bytes differ by eight. GB and GiB are not interchangeable. Protocol overhead, congestion, loss, startup, storage speed and competing traffic make real completion times vary. Efficiency is an assumption, not a measurement.

Technical references

RFC 6349

Reviewed 9 September 2026. Found an issue? Send a correction with a reproducible example.