Calculators / Transfer Time Calculator
📡 Data Transfer Time Calculator
How long will that 500 GB backup, S3 migration, or dataset download actually take? Get realistic estimates that account for protocol overhead.
Uses decimal units (1 GB = 1000 MB) and accounts for real-world protocol overhead (TCP/IP, TLS, retransmits) — typically 5–15% on a healthy link.
Bits vs bytes — the classic trap
Internet speeds are sold in megabits per second (Mbps), but file sizes are measured in megabytes (MB) — and 1 byte = 8 bits. So a "100 Mbps" line moves at most 12.5 MB/s, before overhead. That's why downloads always feel slower than the plan's headline number.
Why add protocol overhead?
TCP/IP headers, TLS encryption, acknowledgements and retransmissions eat 5–15% of raw bandwidth on a healthy connection — more on high-latency or lossy links. The default 10% gives estimates that match real-world transfers much better than the theoretical maximum.
Cloud migration tip
If the estimate runs into weeks, that's exactly why services like AWS Snowball and Azure Data Box exist — for tens of terabytes, shipping disks beats the wire. See our AWS guides for data migration strategies.