This data transfer time calculator tells you how long a file, backup or server migration will take over a given link, what speed you need to finish within a maintenance window, and how decimal and binary units compare. It runs entirely in your browser: nothing you type is sent to our server.
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Table of Contents
How the time is calculated
Time = data size in bits ÷ (link speed × usable share). Link speeds are always in bits per second (1 Gbps = 1,000,000,000 bits/s) while files are measured in bytes, so the calculator multiplies by 8. The usable share covers TCP/IP overhead and real-world conditions: about 90-95% on a clean wired link, less over VPNs, Wi-Fi or long distances.
| Example | At 100% | At 90% |
|---|---|---|
| 500 GB over 1 Gbps | 1 h 6 min 40 s | 1 h 14 min 4 s |
| 2 TB within 8 hours | 556 Mbps needed | 617 Mbps needed |
GB or GiB?
Disk makers and network speeds use decimal units (1 GB = 1,000,000,000 bytes). Linux tools such as df -h and du -h and Windows Explorer use binary units (1 GiB = 1,073,741,824 bytes), often still labelled GB. A “1 TB” disk therefore shows about 931 GiB. Use the converter to compare like with like.
Planning a server migration
- Measure real throughput first: copy a 1 GB test file with
rsync --progressor runiperf3between the two servers. - Many small files (mail, WordPress uploads) transfer far slower than one large file; plan extra time or archive them first.
- Do a first full sync in advance and a short final sync during the cutover. See migrating cPanel accounts to a new server.
How we checked it
We checked the results against hand calculations on 11-12 October 2026: 500 GB at 1 Gbps (4,000 s at 100%), 2 TB in 8 hours at 90% (617.28 Mbps) and the TB/TiB conversions (1 TB = 931.32 GiB).
Frequently asked questions
How long does it take to transfer 1 TB at 1 Gbps?
About 2 hours 13 minutes at the full 1 Gbps, or about 2 hours 28 minutes at a realistic 90%.
Why is my transfer slower than the calculation?
Disk speed, many small files, encryption overhead, latency on long links and other traffic all reduce throughput. Measure with iperf3 to separate network limits from disk limits.
What is the difference between MB/s and Mbps?
MB/s is megabytes per second, Mbps is megabits per second. 1 MB/s = 8 Mbps, so a 1 Gbps link moves at most 125 MB/s.