Bandwidth & Transfer Time Calculator
How long will a backup, upload or migration take? Enter the size and link speed – with a realistic overhead allowance.
How long will a 2 TB backup take over a 100 Mbps link? Will tonight’s migration window be enough? Enter the size and the speed, choose a realistic overhead, and get the transfer time – plus a comparison for 10 Mbps to 10 Gbps so you can make the case for a faster link.
Why real transfers are slower
- Bits vs bytes: 100 Mbps is 12.5 MB/s before anything else.
- TCP/IP and encryption headers take 3–10 %.
- Latency limits single TCP streams on long links – use parallel transfers (Robocopy
/MT, rclone, multiple rsync jobs). - Disks, especially many small files, are often the real bottleneck.
Frequently asked questions
Why is 100 Mbps only about 12 MB/s?
Link speeds are in bits; file sizes are in bytes. Divide by 8 – then lose a little more to TCP/IP headers and retransmits.
More tools
All tools →IPv4 Address Converter
Convert an IPv4 address to decimal, hex, binary, octal and its IPv4-mapped IPv6 form – and back.
Open tool NetworkMAC Address Converter
Reformat a MAC address for Windows, Linux or Cisco, check its unicast/multicast and local/global bits, and derive the EUI-64 IPv6 link-local address.
Open tool NetworkIPv6 Cheat Sheet
IPv6 address types, special prefixes and prefix sizes on one page – a quick reference for planning and troubleshooting.
Open tool