Result
This page has no server side at all. The table you paste is parsed by JavaScript inside your own browser, the chart is drawn on a canvas element on your machine, and the export file is assembled locally. Nothing is uploaded, stored or written to any log. You can disconnect from the network after the page has loaded and everything will still work — which is the simplest way to verify the claim yourself.
Facts and limits of this method
| Time formula | time = volume / speed |
|---|---|
| Volume formula | volume = speed × time |
| Speed formula | speed = volume / time |
| Three fields, three modes | In each mode, the field currently being solved for is hidden |
When it misleads you
- As with other network calculations, data volume uses binary units (1 GB = 1024³ bytes) while connection speed uses decimal units (1 Mbps = 1,000,000 bit/s, as stated by ISPs) — this is the standard combination for network calculations, not a mistake.
- The calculation assumes a constant connection speed throughout the transfer — real internet connection speed typically fluctuates, so actual time may differ from the calculated value.
- The calculator doesn't account for transfer-protocol overhead (TCP/TLS headers, retransmissions) — for a more accurate real-world time estimate, add a 5–15% margin.
- In speed-calculation mode, the result is shown in megabits per second (Mbps) — the standard unit ISPs typically use for stating plan speeds.
How it is calculated
Depending on the selected mode, the form hides the field that needs to be calculated, leaving two fields for the known values.
All entered values are converted to internal base units: data volume to bytes, speed to bytes per second, time to seconds.
The missing quantity is computed using one of three interrelated formulas: time = volume / speed, volume = speed × time, speed = volume / time.
The result is formatted in a convenient unit (minutes for time, gigabytes for volume, megabits per second for speed) and updates instantly whenever any parameter changes.
Questions and answers
How is this different from the file download time calculator?
The download time calculator always computes only time from volume and speed, while this calculator can solve for any of the three directions — including finding the connection speed needed to transfer a known amount of data within a given time.
How do I find out what internet speed I need to transfer a file within a certain time?
Choose the "Connection speed" mode, enter the data volume and the desired transfer time — the calculator shows the minimum required connection speed in megabits per second.
Why is real transfer time usually longer than the calculated value?
The calculation doesn't account for protocol overhead, fluctuations in real connection speed, or sharing the connection with other devices — actual time is usually 5–20% longer than the theoretical minimum.
Is my data sent anywhere?
No, the whole calculation runs in your browser.