Download Time Calculator
How long will that download take? Enter a file size and your connection speed — or pick a preset like a 4K movie or a 100 GB game — and get the time, including a real-world estimate with protocol overhead.
Theoretical download time
33 min 20 sec
Real-world estimate with ~10% protocol overhead: 36 min 40 sec
File sizes are in megabytes (MB); connection speeds are in megabits per second (Mbps) — 8 bits per byte is why a 100 Mbps line moves only 12.5 MB each second.
The Bits-vs-Bytes Math
Files are measured in bytes (MB, GB) but connections in bits per second (Mbps) — and one byte is eight bits. That factor of eight is the single most common source of confusion: a 100 Mbps connection moves 12.5 megabytes per second, not 100.
Formula
Seconds = (File size in MB × 8) ÷ Speed in Mbps Example (25 GB movie on 300 Mbps): 25,000 MB × 8 = 200,000 megabits 200,000 ÷ 300 = 667 sec ≈ 11 minutes
Frequently Asked Questions
How long does a 100 GB game download take?
Theoretical times: about 2 hours 13 minutes at 100 Mbps, 44 minutes at 300 Mbps, and 13 minutes at 1 Gbps. Real downloads run 10–30% longer due to protocol overhead and server-side limits — launchers like Steam often cap below your line speed.
Why are my downloads slower than the speed I pay for?
Your plan speed is the line's maximum, but real downloads are limited by protocol overhead (~5–10%), the serving host's own caps, Wi-Fi conditions, and other devices sharing the connection. Hitting 80–90% of the advertised rate on a wired connection is normal and healthy.
Does Wi-Fi make downloads slower than ethernet?
Often, yes. Even fast Wi-Fi loses throughput to distance, walls, and channel congestion — it's common for a 500 Mbps plan to test at 200–350 Mbps over Wi-Fi but the full rate over a cable. For huge downloads, plugging in can halve the wait.
Do upload speeds matter for downloading?
Barely — downloads send small acknowledgment packets upstream, so only a severely constrained upload (heavily loaded, or sub-1 Mbps) throttles a download. Upload speed matters for video calls, cloud backup, and streaming yourself, not for pulling files down.