Download Time Calculator
How long to download a file at a given connection speed.
Result
Time (seconds)
800
Time (minutes)
13.33
How it works
Download time is file size divided by connection speed, once both are in the same unit. The catch is that file sizes come in bytes and connection speeds in bits — and one byte is eight bits, which is why the size is multiplied by 8 before dividing. So a 1,000 MB file on a 100 Mbps line takes 1,000 × 8 ÷ 100 = 80 seconds in theory. That "in theory" matters: real transfers run slower because of protocol overhead, server limits, Wi-Fi losses and other devices sharing the line. Advertised speeds are usually a maximum, not a guarantee, and the bottleneck is often nowhere near your subscription. A distant or throttled server, an old Wi-Fi router or a congested evening on a shared network will each cap the transfer well below what you pay for.
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Frequently asked questions
Why multiply by 8?
Because 1 byte = 8 bits. File sizes use bytes (MB); speeds use bits (Mbps).
Why is the real time longer?
Overhead, server limits and Wi-Fi mean you rarely get the full advertised speed.
Is uploading as fast as downloading?
Rarely. Most ADSL and cable connections are asymmetric, with upload several times slower than download. Fibre is often symmetric — check the two figures separately in your plan.
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