Cloud Transfer Time Calculator

How Transfer Times Are Calculated

Calculating network transfer speed is more nuanced than dividing file size by your advertised internet package speed. Network engineers account for the difference between bits and bytes, as well as protocol-level overhead:

• Bits vs. Bytes: File sizes are measured in bytes ($1\text{ Byte} = 8\text{ bits}$), while ISP connection speeds are advertised in bits per second (Mbps or Gbps). A 100 Mbps internet connection theoretically transfers at a maximum of 12.5 MB/s ($100 \div 8$).
• TCP/IP Protocol Overhead: Real-world transfers incur an 8% to 12% overhead due to TCP packet headers, IP packet routing, TLS/SSL encryption frames, and packet acknowledgements (ACKs). Our calculator includes a realistic 10% TCP/TLS overhead buffer.
• Google Drive Resumable Upload Chunking: Google Drive's API accepts uploads in multiples of 256 KiB chunks (SaveInDrive utilizes adaptive 8 MB to 32 MB chunks). Each chunk boundary requires HTTP round-trip negotiation with Google's servers.

The Asymmetric Upload Bottleneck

Most residential cable and DSL internet connections are asymmetric. For instance, a home plan might advertise 300 Mbps download speed but provide only 20 Mbps upload speed.

When transferring a 25 GB video file to Google Drive manually:

1. Downloading takes approximately 13 minutes on a 300 Mbps connection.
2. Re-uploading the file on a 20 Mbps upload connection takes over 3 hours and 15 minutes.
3. Your computer must remain awake and connected during the entire 3.5 hour period, and you consume 50 GB of your ISP data plan (25 GB down + 25 GB up).

Reference Transfer Time Table