I am planning to make a Full Install USB from a Windows 10 computer in order to make a Ubuntu Bootable USB Stick.

So I followed each step of the Ubuntu tutorial but I face a problem at the "6. Write the ISO" Section.

Cluster size: 4096 bytes (Default)

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While the default Cluster size in Rufus for the version 18.04.2 LTS amd64 of Ubuntu Desktop is:

Cluster size: 8192 bytes (Default)

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Which Cluster size should I chose between 4096 bytes and 8192 bytes ?

  • I don't think it makes much difference.
    – Pilot6
    Mar 9, 2019 at 17:38

1 Answer 1


Rufus developer here. Unless you know what you're doing, you should just go with the default.

The default cluster size is dependent of the size of your USB drive, which is why drives of different sizes don't always have the same default (e.g. it may be 4096 for some drives, 8192for others, etc.)

I have yet to see a single report, from the millions and millions of people who have ever used Rufus, indicating that using one cluster size compared to another could prevent a drive from booting. The only thing it may change (slightly) is how fast individual files can be read or written, but it certainly does not need to be set to a specific value for the drive to boot. Thus, unless you know what you are doing, just use the proposed default, even if it doesn't match the screenshots you see, and don't worry about it.


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