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Download time calculator

Estimate how long a list of files takes to download at a given connection speed.

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Output
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Download time calculator
Paste a list of files, one per line, as name;size — for example video.mp4;4.7 GB — and this tool calculates how long each one takes to download at your connection speed, plus the total for the whole list. It's built for planning a release, sizing a backup job, or just answering "how long will this take" before you start a transfer.
Set the line speed and its unit — Mbps and Gbps are megabits and gigabits per second, the way ISPs advertise a plan, while MB/s is megabytes per second, the way a browser's download manager reports progress. Protocol overhead knocks a percentage off the raw speed to account for TCP/IP headers and retransmits, since real transfers rarely hit the theoretical maximum. The file size units option decides how an ambiguous "GB" or "MB" in your list is read — 1000-based (decimal, the SI convention) or 1024-based (binary) — while an explicit KiB, MiB or GiB is always read as 1024-based regardless of that setting. Turn on the comparison column to see the same list at a second speed side by side, and sort by download time to put the fastest or slowest transfer first.
Sizes accept a plain number of bytes or a number with a unit (B, KB, MB, GB, TB, and their KiB/MiB/GiB/TiB counterparts), with either a dot or a comma as the decimal mark. Time is shown as h:mm:ss or spelled out in words, your choice, and a total row sums every file's size and time across the whole list.
Everything runs in your browser — the list of file names and sizes is never uploaded anywhere. Copy the result, download it as a .txt file, or send it to another tool's input to keep working with it.
FAQ
What format does the input need to be in?
One file per line, as name;size — for example video.mp4;4.7 GB. The size can be a plain number of bytes or a number with a unit like KB, MB, GB or TB.
What does protocol overhead do?
It reduces the raw line speed by a percentage before calculating time, to account for TCP/IP headers, retransmits and other real-world losses that keep a connection from ever reaching its theoretical maximum.
Why does the same "GB" give a different time depending on an option?
The file size units option decides whether a plain GB, MB or KB in your list means 1000-based (decimal) or 1024-based (binary) bytes. An explicit GiB, MiB or KiB always means 1024-based, whatever that option is set to.
Can I compare two connection speeds at once?
Yes. Turn on "Compare with a second speed" and the table adds a column showing each file's download time at that second speed too.
Is my file list uploaded anywhere?
No. The calculation runs entirely in your browser — the file names and sizes you paste never leave your device.