How long does it take to download 20 GB at 100 Mbps?
26 min 40 sec Theoretical minimum at full line rate (12.5 MB/s), real downloads typically run 5–15% slower. Edit the calculator and this updates live.
Mbps vs MB/s, why the math says 26 min 40 sec
Internet plans are sold in megabits per second (Mbps, small b). File sizes are shown in megabytes (MB, big B). One byte is 8 bits, so a 100 Mbps connection moves at most 12.5 MB of file data per second, divide your plan speed by 8 to get the number your download manager shows.
That factor of 8 is why a "100 meg" plan doesn't download a 100 MB file in one second: it needs 8 seconds in theory, and a little more in practice once protocol overhead (typically 5–15%), Wi-Fi conditions, and server limits are counted.
time = (20 GB × 8 bits/byte) ÷ 100 Mbps = 26 min 40 sec
20 GB at every common speed
| Connection speed | Download time |
|---|---|
| 5 Mbps | 8 hr 53 min 20 sec |
| 10 Mbps | 4 hr 26 min 40 sec |
| 25 Mbps | 1 hr 46 min 40 sec |
| 50 Mbps | 53 min 20 sec |
| 100 Mbps (this page) | 26 min 40 sec |
| 200 Mbps | 13 min 20 sec |
| 300 Mbps | 8 min 53 sec |
| 500 Mbps | 5 min 20 sec |
| 1 Gbps | 2 min 40 sec |
Other file sizes at 100 Mbps
| File size | Download time |
|---|---|
| 100 MB | 8 sec |
| 250 MB | 20 sec |
| 500 MB | 40 sec |
| 1 GB | 1 min 20 sec |
| 2 GB | 2 min 40 sec |
| 5 GB | 6 min 40 sec |
| 10 GB | 13 min 20 sec |
| 20 GB (this page) | 26 min 40 sec |
| 50 GB | 1 hr 6 min 40 sec |
| 100 GB | 2 hr 13 min 20 sec |
| 250 GB | 5 hr 33 min 20 sec |
| 500 GB | 11 hr 6 min 40 sec |
| 1 TB | 22 hr 13 min 20 sec |
| 2 TB | 1 day 20 hr 26 min |
Frequently asked questions
How long does 20 GB really take at 100 Mbps?
The theoretical minimum is 26 min 40 sec. Real downloads lose 5–15% to protocol overhead, Wi-Fi conditions, and server throttling, so plan on roughly 29 min 20 sec to 30 min 40 sec.
What is 100 Mbps in MB/s?
100 megabits per second equals 12.5 megabytes per second (divide by 8, because one byte is 8 bits). Your download manager reports MB/s, which is why the number looks smaller than your plan speed.
What speed do I need to download 20 GB in under 10 minutes?
At least 267 Mbps of real throughput. Add ~10% headroom for overhead when choosing a plan.
How long would 20 GB take on gigabit (1 Gbps)?
2 min 40 sec, about 10× faster than 100 Mbps.