Download Time Calculator
Estimate how long a download will take from a file size and your connection speed — or work out the speed you need to finish in a given time.
How download time is calculated
The math is simple: time = file size ÷ speed, once both are in the same unit. The catch is bits versus bytes. Internet plans are sold in megabits per second (Mbps), but file sizes are in megabytes (MB), and there are 8 bits in a byte. So a 100 Mbps connection moves about 12.5 MB every second — the calculator handles that conversion for you.
Why real downloads run slower
This is a theoretical best case. Expect real transfers to land 10–30% slower because of TCP/IP overhead, the server's own upload limits, Wi-Fi signal, and network congestion. If you regularly download large files like Linux ISOs, a nearby mirror usually beats a distant origin server.
Quick reference
| Connection | Throughput | 1 GB takes |
|---|---|---|
| 25 Mbps | ~3.1 MB/s | ~5m 20s |
| 100 Mbps | ~12.5 MB/s | ~1m 20s |
| 500 Mbps | ~62.5 MB/s | ~16s |
| 1 Gbps | ~125 MB/s | ~8s |
Frequently asked questions
How is download time calculated?
Download time equals the file size in bits divided by the connection speed in bits per second. We convert your file-size and speed units to a common base, account for bits versus bytes, then format the result.
Why is my real download slower than the estimate?
The estimate assumes you get your full advertised speed with no overhead. In practice protocol overhead, server limits, Wi-Fi, and congestion mean real transfers are usually 10-30% slower than the theoretical figure.
What is the difference between Mbps and MB/s?
Mbps is megabits per second and is how internet plans are advertised. MB/s is megabytes per second, what download managers usually show. There are 8 bits in a byte, so 100 Mbps is about 12.5 MB/s.
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