See size of Windows 10 updates

Solution 1:

You can download this third party software which will let you see the update size: https://winaero.com/blog/how-to-see-size-of-windows-10-updates/

Solution 2:

With the Windows 10TP you have little control over the updates. Since it is a test version, Microsoft updates it automatically so that everybody is on the same page.

The size of updates will depend on what it is. For 'normal' updates the sizes are similar to Windows 7 - meaning an update of the Defender definition files is a few KBs and an update of e.g. Silverlight or Net Framework may be 100 or more MBs.

But the real biggies are the new builds. The last build 10074 was 2.5GBs for the ESD (the installation file) and the prior builds were in that same order of magnitude. And those you get too on a regular appr. monthly basis

Solution 3:

Set your connection as a metered connection.

To do this Click on the wifi icon in taskbar and choose your connection. There's a link named "properties" . Click on it .Then your connection properties will appear. There's a button named as "Set as metered connection". Turn it on and your connection will be a metered connection. 

Go to Windows Update setting and check for updates.  This won't probably download the update but tells you what is the size of the update: