The Fileflow method
File size, link rate,
and the wait between.
Fileflow models one combined transfer at a constant rate you supply. It makes the conversion between bytes and bits visible, then applies an optional usable-throughput allowance. It does not measure a connection or touch the files themselves.
Start with the units, not the stopwatch
A byte contains eight bits. In this calculator, an uppercase B always means bytes. The size unit MB means one million bytes, while MiB means 1,048,576 bytes. A bit rate such as Mbps uses a lowercase b and a decimal multiplier: 1 Mbps is 1,000,000 bits per second. The rate selector contains only bit-rate units, so there is no ambiguous “MBps” option.
| Decimal | Bytes | Binary | Bytes |
|---|---|---|---|
| kB | 1,000 | KiB | 1,024 |
| MB | 1,000,000 | MiB | 1,048,576 |
| GB | 1,000,000,000 | GiB | 1,073,741,824 |
| TB | 1,000,000,000,000 | TiB | 1,099,511,627,776 |
Use the label shown by the source of your size information. A display saying “GB” may not tell you how another application has counted bytes; if the distinction matters, check the byte count rather than silently treating GB and GiB as interchangeable. The optional row label is for your own organisation and does not affect the arithmetic.
Two durations from the same sizes
First, each row is converted into bytes and the rows are added. This combined byte total is multiplied by eight to give bits. The theoretical duration divides those bits by the full entered bit rate. The adjusted duration instead divides by the effective rate after applying your percentage.
Effective bits/s = entered bits/s × usable percentage ÷ 100
Estimated seconds = combined bytes × 8 ÷ effective bits/s
The default 80% is simply an example that makes the allowance visible. It is not a measurement, a typical efficiency claim or a recommendation for your network. Choose an assumption appropriate to your task, or use a measured effective rate with the percentage set to 100. Entering an effective rate and then reducing it again would apply an allowance twice.
Example 1: the eight-to-one conversion
Enter 8 MB, an entered rate of 8 Mbps, and 100% usable throughput.
8 MB = 8,000,000 bytes = 64,000,000 bits. Divide by 8,000,000 bits/s and both durations are exactly 8 seconds.
Change usable throughput to 50%. The effective rate is now 4,000,000 bits/s, and the adjusted estimate is 16 seconds. The theoretical estimate remains 8 seconds.
Example 2: mixing folder-size units
Suppose one folder is entered as 8 GB and another as 2 GiB. The first contributes 8,000,000,000 bytes; the second contributes 2,147,483,648 bytes. Their total is 10,147,483,648 bytes, rather than “10 GB” with a silently mixed definition.
At 100 Mbps with 80% usable throughput, the effective rate is 80,000,000 bits/s. The adjusted duration is exactly 1,014.7483648 seconds. The result’s whole-second breakdown rounds up to 16 min 55 sec. At the full entered rate the theoretical duration is 811.79869184 seconds, shown as 13 min 32 sec. The text export also preserves exact rational seconds, so display rounding does not become a new input.
Example 3: upload speed changes the plan
A 10 GB upload contains 80,000,000,000 bits. At an entered upload rate of 20 Mbps and 80% usable throughput, divide by 16,000,000 bits/s. The adjusted estimate is 5,000 seconds, or 1 hr 23 min 20 sec. Its theoretical estimate is 4,000 seconds, or 1 hr 6 min 40 sec. A faster download allowance would not describe that upload.
When your measured rate is in bytes per second
Convert the byte rate to a bit rate before entering it. For example, a sustained 8 MB/s in decimal units is 64 Mbps. A sustained 8 MiB/s is 67.108864 Mbps. In both cases, choose 100% if that rate already represents the usable throughput you intend to model. Fileflow does not run the measurement or validate that it is representative of the next transfer.
How decimals and rounding work
Each numeric input accepts up to six decimal places, with a leading zero for values below one. Use 0.5 rather than .5, and omit commas and scientific notation. Fileflow uses integer fractions internally for conversion and division; it does not round each row before adding it. A rounded size such as 0.1 KiB corresponds to 102.4 byte-equivalents in this model. That is an estimated input, not a claim that a physical file contains a fraction of a byte.
The combined byte display and seconds display use up to six decimals. The familiar day/hour/minute/second breakdown rounds a positive duration up to the next whole second. For a duration below one second, the result uses up to six decimal places; extremely small values are labelled below 0.000001 seconds. Exports include exact fractions when needed. Zero total size produces zero modelled duration; it is not evidence of an actual completed transfer.
Where this simple model stops
All rows form one combined data amount. Fileflow does not simulate parallel streams, pauses, compression, retry schedules, server limits, changing wireless conditions or per-file setup time. Small-file transfers can spend substantial time on work that a constant-throughput model does not represent. The usable percentage provides one overall assumption; it cannot recreate every bottleneck.
There is no start-time entry or guaranteed finish time. Compare scenarios by changing the rate or allowance and recalculating, rather than treating the result as a service promise. Avoid entering confidential file names in labels if you plan to share the exported plan.
Return to the calculator to build an estimate. For arithmetic corrections, use the shared contact inbox and include the exact values, units and expected result.