When we talk about data transfer rates most people use kbps, Mbps, Gbps. But a lot of programs use KB/sec. The table below can be used as a cheat sheet for quick conversions.
The table below uses "Kilo/Mega/Giga bits" for connection speed and "Kilo/Mega/Giga bytes" for download speed.
| Connection Method | Connection Speed |
Maximum Theoretical Download Speed |
File Transfer Time 1 GB File |
| 28.8K Modem | 28.8-kbps | 3.6-KB/sec | 2+ Days |
| 33.6K Modem | 33.6-kbps | 4.2-KB/sec | 2 Days 18 hours |
| 56K Modem | 53.3-kbps | 6.6-KB/sec | 2 Days |
| One-channel ISDN | 56-kbps | 7-KB/sec | 1 Day 18h 36m |
| One-channel ISDN | 64-kbps | 8-KB/sec | 34h 43m |
| Two-channel ISDN | 115.2-kbps | 14.4-KB/sec | 21h 30m |
| Two-channel ISDN | 128-kbps | 16-KB/sec | 17h 21m |
| Fractional T-1 | 256-kbps | 32-KB/sec | 8h 40m |
| 384K DSL | 384-kbps | 48-KB/sec | 6h |
| Satellite | 400-kbps | 50-KB/sec | 3h 55m |
| Fractional T-1 | 512-kbps | 64-KB/sec | 4h 20m |
| DSL/Fract. T-1 | 768-kbps | 96-KB/sec | 3h |
| 1-mbps DSL | 1,000-kbps | 125-KB/sec | 2h 10m |
| T-1 (1.544-mbps) | 1544-kbps | 193-KB/sec | 1h 26m |
| E1 2 Mbps | 2000-kbps | 250-KB/sec | 1h 5m |
| 10-Base-T | 10-Mbps | 1.25-MB/sec | 13m |
| ATM25 | 25.6-Mbps | 3.2-MB/sec | 5m |
| E3 | 34-Mbps | 4.25-MB/sec | 3m |
| DS3/T3 | 45-Mbps | 5.63-MB/sec | 2m 55s |
| OC1 | 51-Mbps | 6.38-MB/sec | 2m 35s |
| 100Base-T | 100-Mbps | 12.5-MB/sec | 1m 20s |
| OC3 | 155-Mbps | 19.38-MB/sec | 51s |
| OC12 | 622-Mbps | 77.75-MB/sec | 12s |
| 1000Base-T | 1-Gbps | 125-MB/sec | 8s |
| OC48 | 2.4-Gbps | 300-MB/sec | 3s |
| OC192 | 10-Gbps | 1.25-GB/sec | 1s |
The following factors need to be considered when measuring network speeds:
- Latency & jitter
- physical signaling overhead
- TCP overhead
Typically on a clean line you will see anywhere from 10% to 25% loss due to factors mentioned above.
