Downloads
How long does 1 GB take to download at 100 Mbps?
1 min 24 s
to download 1 GB at 100 Mbps, best case. Typical: 1 min 40 s (at 80 % efficiency, our estimate for Wi-Fi and busy servers).
Internet speeds are sold in megabits per second, file sizes in megabytes. A byte is 8 bits, so 100 Mbps moves at most 12.5 megabytes each second.
The arithmetic
- 1 GB × 8 bits per byte = 8 gigabits (8,000,000,000 bits)
- 100 Mbps = 100,000,000 bits per second = 12.5 MB/s at most
- 8,000,000,000 ÷ 100,000,000 = 80 s = 1 min 20 s with zero overhead
- TCP/IP and Ethernet framing use about 5 % of the line (1,460 data bytes per 1,538 on the wire): 80 ÷ 0.949 = 1 min 24 s
If the size is really 1 GiB (some stores and Windows label GiB as GB), it is 7.4 % bigger: 1 min 30 s best case.
| Speed | Best case (95 %) | Typical (80 %, estimate) |
|---|---|---|
| 10 Mbps | 14 min 3 s | 16 min 40 s |
| 25 Mbps | 5 min 37 s | 6 min 40 s |
| 50 Mbps | 2 min 49 s | 3 min 20 s |
| 100 Mbps | 1 min 24 s | 1 min 40 s |
| 300 Mbps | 28 s | 33 s |
| 500 Mbps | 17 s | 20 s |
| 1,000 Mbps | 8 s | 10 s |
Sources and assumptions
- Overhead: 94.9 % efficiency from TCP/IPv4 on 1,500-byte Ethernet frames (computed); 80 % 'typical' is our estimate.