Calculate upload time

Enter the file size and actual upload rate

For a useful result you need two numbers: the size of the file you want to send and the speed at which your connection sends data. The direction is crucial. When uploading, you're limited by the upload rate. The download rate describes receiving data and can't simply be used instead, even if it is more prominent in your contract or test result.

Where to get the upload speed

The most reliable figure is one you have measured on your own connection. A speed test that reports download and upload separately is suitable for this. Take the upload figure from it and pay attention to the unit. A plan description such as “up to …” states a contractual maximum, not a measured value. This calculator doesn't measure anything itself. It works only with the numbers you enter. The actual rate can also change during a transfer. The result therefore always describes a constant rate.

Units and number format

• File size: B, KB, MB, GB, MiB or GiB. KB, MB and GB are calculated as decimal units, so 1 MB = 1,000,000 bytes. MiB and GiB are calculated as binary units, so 1 MiB = 1,048,576 bytes.
• Speed: Kbit/s, Mbit/s, Gbit/s or MB/s. The selected unit changes the calculation and is not just a label. 2 MB/s is eight times as fast as 2 Mbit/s.
• The most precise input is the exact byte count from the file properties, entered in B. After conversion, the size must come to a whole number of bytes.
• Separate decimal places with a period; a comma is not accepted as a decimal separator and can only group thousands. A period always counts as a decimal separator, so 1.000 means 1. Write a thousand as 1000, 1,000 or 1,000.00.
• A file of 0 bytes is allowed and gives a duration of 0 seconds. The speed must be greater than 0.
• The efficiency must be above 0 and no more than 100 percent. The starting value of 90 percent is only an example of an assumption, not a recommendation.

Not sure whether a size figure is meant as decimal or binary? Then you can first convert KB, MB and MiB and then choose the appropriate unit.

From file bytes to seconds

File sizes are given in bytes, while line rates are usually given in bits per second. Before you can divide, both values must use the same base unit. The calculator works in four steps:

1. It converts the file size into bytes. 10 MB becomes 10,000,000 bytes.
2. It multiplies the bytes by 8, because one byte consists of 8 bits. That gives 80,000,000 bits.
3. It converts the upload rate into bits per second. 10 Mbit/s is 10,000,000 bit/s.
4. It divides the bits by the bits per second to get the ideal duration: 80,000,000 ÷ 10,000,000 = 8 seconds.

As a formula: ideal seconds = bytes × 8 ÷ (Mbit/s × 1,000,000). For 10 MiB instead of 10 MB, the calculator uses 10,485,760 bytes. At the same 10 Mbit/s, that gives 8.388608 seconds. The difference is small, but it shows that the correct size unit matters.

Why MB/s and Mbit/s are not the same

MB/s counts megabytes per second, while Mbit/s counts megabits per second. One byte has 8 bits, so 1 MB/s equals exactly 8 Mbit/s. A megabit is 1,000,000 bits and a megabyte is 1,000,000 bytes, not 1,000.

Here is an example with the same actual rate, calculated as the ideal duration at 100 percent efficiency: a 25 MB file is uploaded at 2 MB/s. Calculated in bytes, that gives 25 ÷ 2 = 12.5 seconds. Calculated in bits, the file has 200,000,000 bits, and 2 MB/s is 16 Mbit/s. 200,000,000 ÷ 16,000,000 also gives 12.5 seconds. If, however, you accidentally choose Mbit/s and enter 2, the calculator works with a rate eight times smaller, and the ideal duration is 100 seconds instead of 12.5 seconds. With the default efficiency of 90 percent, the adjusted duration is longer in each case: rounded, 13.888889 seconds at 2 MB/s and 111.111111 seconds at 2 Mbit/s. So check which unit your measured value is given in.

Double the rate, half the time

For the same file, the duration falls in the same proportion as the rate rises. For a 100 MB file, 5, 10 and 20 Mbit/s theoretically give 160, 80 and 40 seconds.

Ideal value and assumed efficiency

The calculator shows you two durations. The ideal duration applies if the entered rate is fully available for your file the entire time. The adjusted duration takes into account the efficiency you set. This is the share of the entered rate that you assume is actually usable. Depending on their length, both durations are shown in seconds, minutes or hours. For the adjusted duration, there is also a detail line with the number of seconds, rounded to six decimal places.

The formula is: adjusted duration = ideal duration ÷ (efficiency ÷ 100). At 100 percent, both values are the same. At 80 percent, 8 Mbit/s of 10 Mbit/s remains usable in theory, and the 8 seconds for 10 MB become 10 seconds. If you halve the efficiency, the adjusted duration doubles.

Is 10 percent loss the same as 90 percent efficiency?

In this calculator, yes, if you understand the loss as a share of the rate. You enter 10 percent less usable rate as 90 percent efficiency. Some other calculators instead add a percentage to the data volume. That is a different method with a different result, as the last row of the table shows: 80 percent efficiency gives 10 seconds, whereas a 20 percent surcharge on the file gives 9.6 seconds. So don't adopt a percentage from another tool without checking it first.

Which efficiency suits your input?

There is no universally valid value. The efficiency is your assumption, not a measurement. What matters is what the entered rate already accounts for. A plan figure or the nominal rate of a connection describes the maximum the line is supposed to deliver. In that case, a lower percentage can represent a cautious scenario. If, on the other hand, you have measured how fast data actually leaves your connection, applying an additional flat deduction may mean you're deducting twice. In that case, 100 percent may be exactly the scenario you have in mind. If you're unsure, calculate two or three variants and plan with the range.

Transfer is not the whole process

If a portal keeps working for a while after you upload, the upload isn't necessarily still running. Sending a file often involves several stages, and the calculator only covers the first of them:

1. File transfer: The bytes travel over your connection to the destination. The calculator estimates this stage.
2. Waiting time at the destination server: The recipient accepts the file and stores it. This time is not included.
3. Checking and processing of the PDF: Depending on the recipient, the file may, for example, be scanned for viruses, have its content extracted or be converted. This time is not included either.

The calculator includes no time for the last two stages, not even a flat value. How long they take depends on the individual recipient.

Why your real upload may take longer

• The connection is shared: If other devices or programs are using the line at the same time, less is left for your file.
• The measured value is out of date: A speed test captures a particular moment, not the rate during your upload.
• The recipient slows things down: The destination server may also accept data more slowly than your connection could send it.
• The direction is wrong: If you calculated with the download rate and your upload is slower, the estimate will be too short.

The calculated time is therefore a guide for the transfer alone. It does not predict when the recipient will confirm receipt. If a deadline is approaching, it's better not to start the upload at the last minute.

Planning ahead with the finished file

At the same rate and efficiency, the duration grows in exact proportion to the file size. Half as many bytes take half as long. If your PDF is large and the recipient also accepts a smaller version, you can reduce the PDF file size and then calculate with the new size.

This calculator does not predict how much smaller the file will become. That depends on the content of the PDF. So enter the size of the finished, downloaded file, ideally the exact byte count from the file properties.

A fast upload also doesn't mean that the file will be accepted. Recipients can set their own limits, for example on file size, number of files or page count. With the calculator, you can check the upload limits in advance and so test whether your PDF meets them.