Data Transfer Time Calculator

The calculator accounts for protocol overhead and network efficiency, but real-world transfers are also affected by disk read/write speeds, server processing time, network congestion, and background processes competing for bandwidth. The efficiency slider (default 80%) accounts for most of these variables.

Protocol overhead is the extra data that network protocols add to ensure reliable delivery. TCP adds acknowledgement packets and error-checking data (~5% overhead), HTTP adds request headers and keep-alive traffic (~10% overhead), while UDP is leaner with only ~2% overhead. This overhead reduces the effective throughput available for your actual file payload.

The formula is: Time (seconds) = (File size in bytes x 8) / (Bandwidth in bps x Protocol efficiency x Network efficiency). The file size is multiplied by 8 to convert bytes to bits, since network bandwidth is measured in bits per second.

Mbps (megabits per second) is the standard unit for network speeds as advertised by ISPs, while MBps (megabytes per second) describes file sizes and storage speeds. Since there are 8 bits in a byte, a 100 Mbps connection delivers roughly 12.5 MBps of actual file throughput before accounting for overhead.