MundoKit

File transfer time calculator

Enter file size and network speed with explicit units. Adjust network efficiency and add disk speed limits to estimate a steady transfer.

Inputs
%
100% is the ideal example, not a claim about real networks.

Results

Estimated transfer time
80 seconds
Minutes
1.3333
Hours
0.0222
Effective throughput
100 Mbps
Bottleneck
Network
  • Assumes a steady transfer, with disk reads, network and disk writes overlapping. Setup time, latency, congestion, small-file costs and retransmissions may increase elapsed time. Network efficiency applies before disk caps.

Results update as you type. The share link stores your inputs after the # in the address, which is not sent to our server, but anyone you send it to can read them.

How it works

NIST lists 1 byte = 8 bits, 1 GB = 10⁹ bytes and 1 GiB = 2³⁰ bytes. Mbps uses a million bits per second; MB/s uses a million bytes per second. Binary MiB/s uses 2²⁰ bytes per second.

network bps = entered speed in bps × efficiency / 100 effective bps = min(network bps, source read bytes/s × 8, destination write bytes/s × 8) seconds = file bytes × 8 / effective bps

Disk terms apply only when enabled. This assumes reads, transfer and writes overlap. Efficiency is your assumption and defaults to an ideal 100%; there is no universal overhead percentage. RFC 7323 describes TCP window and latency constraints, but this tool does not simulate TCP.

No intermediate values are rounded. Seconds display to three decimals (scientific notation below 0.001 seconds), minutes and hours to four. Zero-sized files give zero transfer time; setup time is excluded. Compression, many small files, contention and changing speed can change actual elapsed time.

Worked examples

Ideal decimal gigabyte

1 GB at 100 Mbps and 100% efficiency takes 1,000,000,000 × 8 / 100,000,000 = 80 seconds.

Binary size with an efficiency assumption

1 GiB at 100 Mbps and an assumed 80% efficiency takes 1,073,741,824 × 8 / 80,000,000 = 107.374 seconds after display rounding.

Frequently asked questions

Are Mbps and MB/s different?
Yes. One MB/s equals 8 Mbps. Capital B means byte; lowercase b means bit.
How much bigger is a GiB than a GB?
A GiB is 1,073,741,824 bytes while a GB is 1,000,000,000 bytes. A GiB is about 7.37% larger than a GB; a GB is about 6.87% smaller than a GiB.
What efficiency should I enter?
Use a measured or assumed sustained fraction of the stated network speed. The default 100% is an ideal scenario, not a typical throughput claim.
Can a disk limit the transfer?
Yes. With disk caps enabled the slowest of effective network, source read and destination write throughput determines the estimate.
Why can my upload take longer?
Congestion, latency, protocol overhead, retransmissions, setup and many small files can reduce throughput or add time.

Sources

Last reviewed 2026-11-14. The method is written out above so you can check our math.