Upload time calculator

How to use the upload time calculator

The calculator needs two numbers. Both are easy to find, but each has a trap.

• File size. Your file manager shows it next to the file name. Pick MB, GB or TB to match what it says.
• Upload speed. Run a speed test on the connection you'll send from, and copy the upload number, not the download one. Speed tests report it in Mbps.
• Direction. It starts on upload. Switch it to download if you're the one receiving the file.

If your speed is in MB/s, as some apps show it, pick MB/s in the unit menu instead. The calculator then skips the conversion.

A worked example. You want to send a 4 GB video from home, and the speed test says 20 Mbps up. That's 4,000 MB, or 32,000 megabits. Divided by 20, that's 1,600 seconds: 26 minutes 40 seconds if nothing slows it down.

The upload time formula

Here's the math the calculator does, so you can check any result by hand:

Time in seconds = size in megabytes × 8 ÷ upload speed in Mbps

The 8 is the whole trick. A byte is 8 bits, and speeds are counted in bits while files are counted in bytes. Forget it and your estimate comes out eight times too short.

The calculator uses decimal units, the way speed tests and internet plans count:

• A megabyte is 1,000,000 bytes.
• A gigabyte is 1,000 MB, so multiply gigabytes by a thousand before you start.
• A megabit is 1,000,000 bits, the unit inside "Mbps".

Some software counts sizes in binary units but still writes "GB". Apple names older systems that did, such as iOS 10 and earlier and OS X Leopard and earlier. A binary gigabyte is 1,073,741,824 bytes, about 7% more than a decimal one. If your size came from software like that, allow a little extra.

If your speed is in Gbps, multiply it by a thousand to get Mbps. To turn any speed or size between bits and bytes, use the Mbps to MB/s converter.

Upload times for common file sizes

Times at a steady speed, rounded. Your real upload will usually take a little longer.

Doubling the speed halves the time, and doubling the file doubles it. That's all the table is.

Why your upload speed is lower than your download speed

On many home plans, the upload speed is far lower than the download speed. A speed test shows both, and only the upload one matters for sending.

Even the FCC's minimum benchmark for fixed broadband asks for much less upload than download. It's 100 Mbps down but only 20 Mbps up. So a connection that streams well can still crawl when you send a big video.

That's why the calculator asks for the upload number. Put in the download number by mistake and the estimate can come out several times too short.

Why real uploads take longer than the estimate

The calculator assumes your full upload speed, all the time. Real transfers lose some of it on the way:

• Packet overhead. Every chunk of data travels with addresses and checks. On a perfect 100 Mbps wired link, the IETF's guide to testing transfers (RFC 6349) puts the most a file can move at 94.9 Mbps.
• Wi-Fi. A weak signal, a wall or a busy channel cuts the speed long before your plan does. A cable usually helps.
• Everything else on the connection. A video call, a cloud backup or a game update shares the same upload.
• The other end. The service receiving the file has its own limits and can slow you down.
• A phone that sleeps. Mobile browsers often pause a page in the background, and the upload stops with it.

So treat the result as the best case. Leave some room on top before a deadline.

What the result means for sending the file

A long upload is only worth it if the file arrives in one piece. SendTheStuff will send a file up to 5 GB as a link, free, at the quality you uploaded. SendTheStuff will carry on after a dropped connection, for up to 3 days after the upload started. A SendTheStuff link will work for 14 days, so your recipient won't have to grab it the same evening.

Email is where most big uploads fail. Gmail, Yahoo and Outlook.com each stop at 25 MB of attachments. A file that needs minutes to upload is far too big for one.

Until SendTheStuff launches

You can still send a big file today:

1. Check the time with the calculator, and plug the computer into the router with a cable if you can.
2. Upload the file to a cloud drive you already use, and share it as a link instead of an attachment.
3. Keep the laptop awake and the tab open until the upload finishes.

The guide to sending files too big for email compares the usual ways. The WeTransfer file size limit page shows how far its free version stretches.