Upload time calculator

Transfer time is file size divided by speed. The trap is that the two are quoted in different units, eight bits apart. Enter a size and a connection speed and this handles the conversion, then shows what compressing the file first would save you.

Speed is measured in

Leave this empty to see the single transfer only.

500 MB at 20 Mbps takes 3 min 30 s. At 100 MB it takes 42 s.

Compressing first removes 2 min 48 s of transfer, so it pays for itself if the encode finishes inside that.

MB here means 1,048,576 bytes, the way your operating system counts. Mbps means 1,000,000 bits per second, the way your ISP counts. Times are the theoretical floor.

The arithmetic and the unit trap

One division, and one conversion that catches almost everyone. File sizes are counted in bytes and connections are sold in bits, so a 100 Mbps line does not move 100 MB per second. It moves an eighth of that, about 12.5 million bytes, which your file manager will round down to roughly 11.9 MB/s because it counts a megabyte as 1,048,576 bytes rather than a million. 

bytes_per_second = Mbps × 1,000,000 / 8
seconds          = size_MB × 1,048,576 / bytes_per_second

Those two definitions of a megabyte differ by about 4.9 percent, which is enough to notice on a long transfer and not enough to change any decision. The factor of eight is the one that matters.

Use your upload speed, not your plan

The number on your bill is the download figure. On cable and DSL the upstream is a small fraction of it, often somewhere between a tenth and a twentieth, because the spectrum was allocated on the assumption that households consume more than they send. Fibre is typically symmetric and is the one case where the advertised number applies in both directions.

This is why uploading a video always feels disproportionately slow. A file that downloads in forty seconds can take fifteen minutes to send back.

Typical connections, both directions

Connection Down Up
Cable, typical plan 100–500 Mbps 10–35 Mbps
Fibre to the home 300–1,000 Mbps 300–1,000 Mbps
VDSL 30–80 Mbps 5–20 Mbps
Mobile, 4G 20–60 Mbps 5–20 Mbps
Mobile, 5G 100–500 Mbps 20–80 Mbps
Hotel or café wifi 5–30 Mbps 1–10 Mbps
  • Cable, typical plan: Upload is a small fraction of download by design.
  • Fibre to the home: Usually symmetric, which changes the arithmetic completely.
  • VDSL: Falls off with distance from the cabinet.
  • Mobile, 4G: Varies hour to hour with how busy the cell is.
  • Mobile, 5G: Good when you have it, and you often do not.
  • Hotel or café wifi: Shared, throttled and the reason this page exists.

Ranges, not promises. Run a speed test and read the upload figure if you want the real number for your line at this hour of the day.

Transfer time by size and speed

Theoretical minimum at each combination, with no overhead and no contention. Real transfers land 10 to 20 percent above these.

File 5 Mbps10 Mbps25 Mbps50 Mbps100 Mbps500 Mbps
25 MB 42 s21 s8 s4 s2 sunder a second
100 MB 2 min 48 s1 min 24 s34 s17 s8 s2 s
500 MB 13 min 59 s6 min 59 s2 min 48 s1 min 24 s42 s8 s
1 GB 28 min 38 s14 min 19 s5 min 44 s2 min 52 s1 min 26 s17 s
5 GB 2 h 23 min1 h 12 min28 min 38 s14 min 19 s7 min 9 s1 min 26 s

1 GB is taken as 1,024 MB. Read the 5 and 10 Mbps columns as upload speeds, which is what most cable connections give you.

Whether compressing first is worth it

The comparison people never run is the one that matters. Uploading a 2 GB phone video on a 10 Mbps upstream takes about 28 minutes. Compressing it to 200 MB first takes a few minutes in a browser tab and leaves you with under 3 minutes of upload. You finish sooner, and you did not have to keep the laptop lid open for half an hour.

The break-even is simple: compressing wins if the encode takes less time than the transfer it removes. On a slow upstream with a large file that is nearly always true. On symmetric fibre with a small file it is nearly always false, and you should just send the original.

It is worth noticing what the standard advice gets backwards here. Most online compressors ask you to upload the full original to their server, wait for them to encode, then download the result. That is the large transfer you were trying to avoid, plus a second one. Compressing locally is faster because the biggest file never crosses the network at all, which is the entire argument for doing it in the browser.

Why the real time is always longer

TCP, TLS and HTTP each add framing bytes that are not your file. The server on the other end has its own limits and may be slower than you are. Anything else on your network is competing for the same upstream, and on wifi you are also competing with your neighbours. A phone that goes to sleep pauses the upload entirely.

Add 10 to 20 percent to anything this page tells you. If the gap is much larger than that, the bottleneck is not your connection.

Questions

How long does it take to upload a 1 GB video?

At 20 Mbps of upload, about 7 minutes. At 5 Mbps, closer to 29 minutes. At 100 Mbps, around 86 seconds. Use your upload speed rather than the number on your bill, because on most cable and DSL connections the upload figure is a fraction of the download figure.

Why is my upload so much slower than my download?

Most consumer connections are deliberately asymmetric. Cable and DSL allocate the majority of the available spectrum to downstream traffic because that is what households mostly do. A 500 Mbps cable plan often carries 20 or 30 Mbps upstream, which is a ratio of about 20 to 1. Fibre is usually symmetric, so it is the one case where the advertised number applies in both directions.

Is Mbps the same as MB/s?

No, and the difference is a factor of eight. Mbps is megabits per second and is what internet plans are sold in. MB/s is megabytes per second and is what a transfer progress bar usually shows. A 100 Mbps connection moves about 12.5 million bytes per second, which a file manager will display as roughly 11.9 MB/s.

Is it faster to compress a video before uploading it?

For a large file on a slow upstream, almost always. Compressing a 2 GB file down to 200 MB removes about 90 percent of the transfer, and a browser encode finishes long before an hour of uploading would. For a 20 MB file on fibre it is not worth the trouble. The break-even is whether the encode takes less time than the upload it removes.

Why does my transfer never hit the speed I pay for?

Protocol overhead takes a few percent, the far end may be slower than you are, and any other device on the network is competing for the same link. Treat the calculated time as a floor and add 10 to 20 percent for anything real.

Related tools

Compress it before you send it