MB Networks
Speed · Size · Time
How long will your transfer take?
Enter a file size and link speed — see theoretical and real-world transfer times instantly.
Theoretical time
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Wired (~88%)
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Wi-Fi (~65%)
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Throughput
0MB/s
Size
0GB
Configuration
File size quick-pick
Link speed quick-pick
Why the estimate isn't just size ÷ speed
A raw division of file size by link speed gives a theoretical best case that real transfers never actually hit — TCP overhead, protocol framing, and (for Wi-Fi specifically) the fundamentally half-duplex nature of wireless all eat into usable throughput. This calculator applies realistic efficiency figures (roughly 88% for wired connections, roughly 65% for Wi-Fi) instead of the theoretical maximum, which is why its estimates land much closer to what you'll actually see in a real transfer.
Why Wi-Fi is so much worse than the math alone suggests
Wired Ethernet is full-duplex — send and receive happen simultaneously on separate physical paths. Wi-Fi is fundamentally half-duplex — a device can't transmit and receive at exactly the same instant on the same channel — on top of contention with every other device sharing that same wireless channel. That combination is why a "1 Gbps Wi-Fi 6" link realistically transfers far closer to 600–700 Mbps in practice, not the number on the router's box.
Why is my actual transfer slower than my rated connection speed?
Real transfers never hit theoretical maximum — TCP protocol overhead, framing, and (for Wi-Fi) the fundamentally half-duplex nature of wireless all reduce usable throughput below the rated link speed. This calculator applies realistic efficiency estimates (~88% wired, ~65% Wi-Fi) instead of the theoretical maximum for a more accurate result.
Why is Wi-Fi so much less efficient than wired for large transfers?
Wired Ethernet is full-duplex (send and receive simultaneously on separate paths); Wi-Fi is half-duplex and shares its channel with every other device using it. Both factors reduce real Wi-Fi throughput well below its rated speed, more so than wired connections experience at their rated speed.
Does this tool account for the bottleneck being the slowest link in the chain?
It calculates based on the single link speed you enter — if your actual transfer path includes a slower link anywhere in the chain (a Wi-Fi hop, an older switch port, a slow destination drive), that slowest link is your real bottleneck regardless of how fast the rest of the path is. Enter the speed of whichever link you expect to be the constraint.
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Open →Wired efficiency ~88% accounts for TCP overhead and protocol framing. Wi-Fi ~65% reflects typical real-world half-duplex losses. Actual speeds vary with hardware and congestion.