Network Transfer Time Calculator

Why real transfers are slower than link speed

Ethernet speed is measured in bits per second, while file sizes are usually shown in bytes. Protocol overhead, storage speed, CPU load, file count, encryption, Wi-Fi conditions, and retransmissions reduce application throughput.

For a healthy wired link and large sequential files, 90-94% efficiency is a useful planning range. Small files, Wi-Fi, slow disks, SMB signing, and busy systems can be much lower.

Use the slower component

A 2.5GbE link cannot make a source drive read faster or a destination write faster. If storage throughput is known, convert it to network speed and use the lower limit.

Measured 1GbE example

Our EQi12 large-file SMB test sustained about 102.95–107.15MiB/s over Gigabit Ethernet with matching SHA-256 hashes. Entering a measured application rate is more accurate than assuming the nominal 1Gbps link. A continuous 1TiB transfer near 105MiB/s takes roughly 2.7 hours before additional filesystem or verification work.

The same machine moved 10,000 small files much more slowly because each file adds metadata, open/close, security, and protocol work. Use the network and SMB test to see why one large file and a directory tree need different planning margins.

Choose an efficiency value

Decimal and binary units

This calculator uses decimal GB/TB and decimal Mbps/Gbps, matching network and drive marketing. If your file manager reports GiB or TiB, expect a unit difference. Always state the unit when publishing a result.