Formula
R = (S × 8) ÷ (T × η)
Convert the size to bits and divide by the usable seconds. A lower efficiency requires a faster advertised or raw rate.
Network & data
● Runs locallyRequired Transfer Speed
Work backwards from a file size and deadline to find the sustained transfer speed you need. Enter a target duration in days, hours, minutes and seconds, then account for expected efficiency without confusing bits and bytes.
Example values
Required transfer rate
Assumptions
- The result is a sustained end-to-end rate, not a burst speed.
- Efficiency is applied across the full target duration.
Connection speeds are usually advertised in Mbps or Gbps, while file tools often show MB/s. CalcFlow reports both.
Formula review
Formula v1.0.0
Reviewed 2026-08-03
CalcFlow engineering review
Required Transfer Speed: Worked example
20 GB contains 160 billion bits. Dividing by 1,800 seconds gives 88.8889 Mbps at ideal efficiency.
Frequently asked questions
Does this equal the internet plan I should buy?
Not exactly. The result is sustained application throughput; an access plan may need headroom for protocol overhead, contention and other traffic.
How should I choose efficiency?
Use 100% for a theoretical minimum. A lower value adds headroom when the path, storage or wireless link is imperfect.
Can the duration contain only zeros?
No. A zero duration would require division by zero and an unbounded transfer rate.