File Transfer Time
Estimate how long a file transfer will take at a given connection speed.
About File Transfer Time
File transfer time is the file size (converted to bits) divided by the link's bandwidth, adjusted upward for real-world protocol overhead — packet headers, acknowledgments, retransmissions, and the fact that connections rarely sustain 100% of theoretical link capacity. This calculator applies an overhead percentage on top of the ideal transfer time to give a more realistic estimate.
Formula
Transfer time with overhead
time = file_size / bandwidth × (1 + overhead%)
- S
- File size in bits
- B
- Bandwidth in bits per second
- o
- Overhead percentage
Worked example
With the default values below, File Transfer Time returns Estimated Transfer Time of 44 seconds. Change any input above and every figure here is recalculated in your browser.
Inputs used
- File Sizeminimum 0 MB
- 500 MB
- Link Bandwidthminimum 0.01 Mbps
- 100 Mbps
- Protocol Overheadaccepts 0–100 %
- 10 %
Results
- Estimated Transfer Time
- 44 seconds
- Transfer Time
- 44.00 s
- Ideal (No Overhead) Time
- 40.00 s
- Effective Throughput
- 90.909 Mbps
Step by step
- 1Values used
- 2Transfer time with overhead
- 3Estimated Transfer Time= 44 seconds
- 4Transfer Time= 44.00 s
- 5Ideal (No Overhead) Time= 40.00 s
- 6Effective Throughput= 90.909 Mbps
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why does the transfer take longer than the theoretical minimum?
Real transfers include protocol overhead: TCP/IP headers on every packet, acknowledgment round-trips, occasional retransmissions of lost packets, and slow-start ramp-up at the beginning of the connection — none of which move actual file data.
What overhead percentage should I use?
10-20% is a reasonable estimate for a healthy wired connection. Congested, high-latency, or wireless links can see 30% or more overhead due to retransmissions and reduced effective window sizes.
Why convert MB to bits instead of just dividing by MBps?
Network bandwidth is conventionally quoted in bits per second (Mbps), while file sizes are quoted in bytes (MB). Converting file size to bits (× 8) before dividing keeps the units consistent and avoids an easy 8x error.
Does this use decimal (SI) or binary (IEC) megabytes?
This calculator uses the SI decimal definition (1 MB = 1,000,000 bytes), matching how bandwidth and storage are marketed. See the Bandwidth Calculator for a version that lets you choose binary (MiB) units.