Transfer time

How Long Does It Take to Upload 1 TB at 100 Mbps?

Uploading or downloading a 1 TB file at 100 Mbps takes about 22 hours 13 minutes, assuming the full speed is sustained.

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

Upload or download time

22 h 13 min

100 Mbps is 12.5 MB/s. 1 TB is 1,000,000 MB, and 1,000,000 ÷ 12.5 = 80,000 seconds.

With 10% protocol overhead: about 1 day. 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 1 TB and 100 Mbps; change either value and the answer and both reference tables update.

Open the calculator: 1 TB at 100 Mbps

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

What 1 TB actually is

A terabyte is a full external drive, a multi-camera shoot's worth of ProRes footage, about 25,000 RAW frames, or a year of a small studio's deliverables. It is HeftySend's Premium per-transfer limit and the size at which people start weighing a courier and a hard drive against the internet.

Moving a terabyte online is a question of sustained throughput over many hours or days, so the practical limits are the upload speed you can actually hold, the disk the data sits on, and whether the transfer survives interruptions. On anything slower than a few hundred megabits a drive in a padded envelope is often faster; at gigabit fibre the internet wins comfortably.

4K video (55 Mbps): about 40 hours
1080p video (15 Mbps): about 148 hours
RAW photos (40 MB each): about 25,000
25 MB email attachments: about 40,000

What 100 Mbps actually is

100 Mbps is the most common advertised home broadband speed and the number most people put into a calculator. Downloading at 100 Mbps is everyday; uploading at 100 Mbps means full fibre (FTTP), a symmetric business line or a lucky 5G cell. It moves 12.5 MB of file data a second.

Is 100 Mbps a realistic upload speed? Cable plans sold as 100 Mbps typically upload at 10–20 Mbps, so if you are sending rather than receiving on cable, the 10 Mbps and 25 Mbps figures are usually closer to what you will see. On fibre, 100 Mbps up is a modest, reliably sustained speed.

1 TB at other speeds, and other sizes at 100 Mbps

The first table keeps the file at 1 TB and changes the speed; the second keeps the speed at 100 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".

1 TB at neighbouring connection speeds
Connection speed	Time for 1 TB
25 Mbps	3 d 16 h
50 Mbps	1 d 20 h
100 Mbps	22 h 13 min
500 Mbps	4 h 26 min
1 Gbps	2 h 13 min

In words

1 TB at 25 Mbps takes about 3 days 16 hours.
1 TB at 50 Mbps takes about 1 day 20 hours.
1 TB at 100 Mbps takes about 22 hours 13 minutes.
1 TB at 500 Mbps takes about 4 hours 26 minutes.
1 TB at 1 Gbps takes about 2 hours 13 minutes.

Neighbouring file sizes at 100 Mbps
File size	Time at 100 Mbps
10 GB	13 min 20 s
20 GB	26 min 40 s
50 GB	1 h 6 min
100 GB	2 h 13 min
1 TB	22 h 13 min

In words

10 GB at 100 Mbps takes about 13 minutes 20 seconds.
20 GB at 100 Mbps takes about 26 minutes 40 seconds.
50 GB at 100 Mbps takes about 1 hour 6 minutes.
100 GB at 100 Mbps takes about 2 hours 13 minutes.
1 TB at 100 Mbps takes about 22 hours 13 minutes.

Why it usually takes longer than 22 hours 13 minutes

Protocol overhead

The headline figure assumes every bit of the 100 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 1 TB at 100 Mbps is about 1 day with 10% overhead, 2 hours 13 minutes longer. Quote that figure when someone is waiting for the file.

Upload is not download

The formula gives the same 22 hours 13 minutes for an upload and a download, but the speed you should plug in is rarely the same. 100 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 10 Mbps, which turns 22 hours 13 minutes into about 9 days 6 hours for the same 1 TB. When you are the one sending, run a speed test and use the upload number.

Dropped connections

Over 22 hours 13 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 1 TB at 100 Mbps?

About 22 hours 13 minutes, the same as uploading, because the formula is file size divided by speed in both directions. The practical difference is that 100 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 1 TB on a 100 Mbps plan, this estimate is usually close; if you are uploading, measure your upload speed first.

How long does 1 TB take at 100 Mbps with protocol overhead?

About 1 day once you allow 10% for TCP/IP headers, TLS and HTTP framing, which is 2 hours 13 minutes longer than the raw 22 hours 13 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 1 TB will arrive.

What if my connection only manages half of 100 Mbps while sending 1 TB?

Transfer time scales directly with speed: at 50 Mbps the same 1 TB takes about 1 day 20 hours, and at 25 Mbps about 3 days 16 hours. 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 100 Mbps, and how does that give 22 hours 13 minutes for 1 TB?

100 Mbps is 12.5 MB/s, because there are 8 bits in a byte. 1 TB is 1,000,000 MB, and 1,000,000 ÷ 12.5 = 80,000 seconds, which is 22 hours 13 minutes. The calculator uses decimal units (1 GB = 1,000 MB); a file that Windows reports as 1 TB is about 7% larger in decimal terms and takes correspondingly longer.