Transfer time

How Long Does It Take to Upload 20 GB at 10 Mbps?

Uploading or downloading a 20 GB file at 10 Mbps takes about 4 hours 26 minutes, assuming the full speed is sustained.

By the HeftySend team Last updated 8 October 2026 Free, no sign-up

Upload or download time

4 h 26 min

10 Mbps is 1.25 MB/s. 20 GB is 20,000 MB, and 20,000 ÷ 1.25 = 16,000 seconds.

With 10% protocol overhead: about 4 hours 53 minutes. Assumes the speed holds for the whole transfer.

Calculate your own

Different file size, a speed in MB/s or Gbps, or the 10% overhead switched on? The calculator opens pre-filled with 20 GB and 10 Mbps; change either value and the answer and both reference tables update.

Open the calculator: 20 GB at 10 Mbps

Works without JavaScript; the result is in the page when it loads.

What 20 GB actually is

Twenty gigabytes is a 500-frame RAW photo shoot at about 40 MB a frame, a full afternoon of 4K from a phone or mirrorless camera, a modern indie game, or a quarter's worth of client deliverables zipped together. It is the size of a typical wedding or event photography hand-over.

A 20 GB transfer is long enough that something will interrupt it on a slow link: a laptop lid closing, a Wi-Fi roam, a mobile hand-off between cells. Splitting it into several transfers does not make it faster, but a resumable upload makes an interruption cost seconds instead of a restart from zero.

4K video (55 Mbps): about 48 minutes
1080p video (15 Mbps): about 3 hours
RAW photos (40 MB each): about 500
25 MB email attachments: about 800

What 10 Mbps actually is

10 Mbps is what the upload side of many cable and FTTC/VDSL plans actually delivers, a typical 4G upload indoors, and about the download speed of a good ADSL2+ line. It moves 1.25 MB of file data a second, so a megabyte takes a little under a second and a gigabyte a little over thirteen minutes.

Is 10 Mbps a realistic upload speed? As an upload speed it is realistic, even common: run a speed test on a plan sold as "100 Mbps" cable and 10 Mbps up is a normal result. As a download speed it is slow by today's standards; if that is all you measure, you are on ADSL, a congested mobile cell or Wi-Fi at the edge of its range.

20 GB at other speeds, and other sizes at 10 Mbps

The first table keeps the file at 20 GB and changes the speed; the second keeps the speed at 10 Mbps and changes the file. Rows with their own write-up are linked. Every row is also written out as a sentence under "In words".

20 GB at neighbouring connection speeds
Connection speed	Time for 20 GB
10 Mbps	4 h 26 min
25 Mbps	1 h 46 min
50 Mbps	53 min 20 s
100 Mbps	26 min 40 s
500 Mbps	5 min 20 s

In words

20 GB at 10 Mbps takes about 4 hours 26 minutes.
20 GB at 25 Mbps takes about 1 hour 46 minutes.
20 GB at 50 Mbps takes about 53 minutes 20 seconds.
20 GB at 100 Mbps takes about 26 minutes 40 seconds.
20 GB at 500 Mbps takes about 5 minutes 20 seconds.

Neighbouring file sizes at 10 Mbps
File size	Time at 10 Mbps
5 GB	1 h 6 min
10 GB	2 h 13 min
20 GB	4 h 26 min
50 GB	11 h 6 min
100 GB	22 h 13 min

In words

5 GB at 10 Mbps takes about 1 hour 6 minutes.
10 GB at 10 Mbps takes about 2 hours 13 minutes.
20 GB at 10 Mbps takes about 4 hours 26 minutes.
50 GB at 10 Mbps takes about 11 hours 6 minutes.
100 GB at 10 Mbps takes about 22 hours 13 minutes.

Why it usually takes longer than 4 hours 26 minutes

Protocol overhead

The headline figure assumes every bit of the 10 Mbps carries file data. In practice TCP/IP headers, TLS and HTTP framing take 5–10% of the link, so a more realistic estimate for 20 GB at 10 Mbps is about 4 hours 53 minutes with 10% overhead, 26 minutes 40 seconds longer. Quote that figure when someone is waiting for the file.

Upload is not download

The formula gives the same 4 hours 26 minutes for an upload and a download, but the speed you should plug in is rarely the same. 10 Mbps is usually the download speed of a plan; on an asymmetric cable, 4G or satellite link the upload side of that plan is often around 1 Mbps, which turns 4 hours 26 minutes into about 1 day 20 hours for the same 20 GB. When you are the one sending, run a speed test and use the upload number.

Dropped connections

Over 4 hours 26 minutes something can interrupt the transfer: a Wi-Fi roam, a laptop lid, a mobile hand-off between masts. A plain browser upload starts again from zero; a transfer that uploads in parts and resumes from the last confirmed part loses seconds. HeftySend uploads are resumable by default; the single button below takes you to the uploader.

Sending something big? Let it survive a dropped connection.

HeftySend uploads in parts and resumes from the last confirmed part, so a Wi-Fi blip or a sleeping laptop costs seconds, not the whole transfer. No account needed for transfers up to 100 GB.

Send up to 100 GB free

Frequently asked questions

How long does it take to download 20 GB at 10 Mbps?

About 4 hours 26 minutes, the same as uploading, because the formula is file size divided by speed in both directions. The practical difference is that 10 Mbps is far more likely to be a real download speed than a real upload speed: plans advertise the download figure, and on cable, 4G and satellite the upload side is a fraction of it. If you are downloading 20 GB on a 10 Mbps plan, this estimate is usually close; if you are uploading, measure your upload speed first.

How long does 20 GB take at 10 Mbps with protocol overhead?

About 4 hours 53 minutes once you allow 10% for TCP/IP headers, TLS and HTTP framing, which is 26 minutes 40 seconds longer than the raw 4 hours 26 minutes. Real transfers lose 5–10% of the link rate to that framing, so the overhead figure is the better one to quote when someone asks when 20 GB will arrive.

What if my connection only manages half of 10 Mbps while sending 20 GB?

Transfer time scales directly with speed: at 5 Mbps the same 20 GB takes about 8 hours 53 minutes, and at 2.5 Mbps about 17 hours 46 minutes. Wi-Fi, other devices on the network, a busy receiving server or a laptop on battery can each take a connection well below its headline figure, so a speed test taken right before you send is the only reliable input.

How many megabytes per second is 10 Mbps, and how does that give 4 hours 26 minutes for 20 GB?

10 Mbps is 1.25 MB/s, because there are 8 bits in a byte. 20 GB is 20,000 MB, and 20,000 ÷ 1.25 = 16,000 seconds, which is 4 hours 26 minutes. The calculator uses decimal units (1 GB = 1,000 MB); a file that Windows reports as 20 GB is about 7% larger in decimal terms and takes correspondingly longer.