How to turn a 64GB flash drive into a 32GB one in one easy step …

… and how to turn it back!

Faced with reviewing, for a few more months I’d guess, new Windows notebook computers wanting to update themselves from Version 1607 to Version 1703 of Window 10, I decided to shortcut the process. But something about that left me scratching my head.

Specifically, the flash drive I used as the installation drive halved in size.

If you’re keen on updating the latest version of Windows 10 and are growing impatient with the Windows auto update’s scheduling not yet giving you access to it, you can download and install it yourself. This is particularly useful if you’re updating more than one computer. The update is around 3.5GB, which is quite the download.

Win Download Tool

The procedure’s remarkably easy. You go to the Microsoft Windows 10 download site – – and use either the “Update now” button, or create “Windows 10 installation media”. It was the second I went for. You click the “Download tool now” button. That downloads an app which you can use to manage the whole process of creating an update USB stick or DVD.

I popped in the Lexar S45 64GB USB 3.0 JumpDrive that I reviewed a while back (sad news: the Lexar JumpDrive Tough 64GB I boiled for ten minutes a couple of weeks ago never recovered from the abuse, even after I took it apart and made sure it was thoroughly dry inside) and let the download tool do its stuff. I didn’t stick around to wait. I guess the download and creation of the necessary files – more than 1800 of them, it turns out – on the USB stick took an hour or so. It’s all automatic so you don’t need to be there.

It was time to review a Dell 2-in-1 notebook (check for the review within the week), so I used the USB drive to update it. And noticed that, according to that computer, the drive was only 32GB in size. Of course I immediately doubted my memory, but my review confirmed that it was supposed to be 64GB. A quick check revealed that, yes, it was supposed to be 64GB. Time to wield Windows Disk Management to see what was going on.

Hmmm, only half the USB drive is available for use

You right click on the Windows desktop logo and choose Disk Management, or type “diskmgmt.msc” into the run box, to get it going. That showed that the disk had a total capacity of 59.62GB, but that only 32GB were in the available partition. The other 27.62GB were “Unallocated”.

(Why 59.62GB and not 64 GB? Disk capacities are normally stated on their boxes and packaging using multiples of ten as their KB, MB, GB and Terabyte multipliers. Windows reports capacities using powers of two as the multipliers. Multiply 64 by a billion, then divide by two raised to the thirtieth power and you get 59.605 – close enough. It’s a happy coincidence of the universe in which we live that two to the tenth power is similar to ten cubed: 1024 compared with 1000).

Repart windows 10
Partition deleted, the whole thing becomes “Unallocated”

For some reason Windows will only format drives up to 32GB to FAT32, even though the FAT32 format supports drives of up to two terabytes, or even more with larger sectors. I think Microsoft would prefer that for large drives we use NTFS, or failing that exFAT, but these are less broadly supported outside of Windows than FAT32. Generally one would use a USB drive smaller than 32GB for this job and, so, never notice. But that did leave me with a drive of half the capacity it was supposed to have.

So I fixed it. Here’s what to do if the same thing happens to you.

First, I copied the USB stick’s contents to another (smaller) USB drive so I wouldn’t have to download them again. Then we go back to the Disk Management app. Find the relevant drive. You can tell from the name, which will be the same as shown in Windows Explorer. If it’s a Windows installation driver, it’ll be called ESD-USB.

When creating the new partition on a drive larger than 32GB, you can only used exFAT or NTFS

The left side will be showing the Primary Partition. That’s the remaining bit that you can see in Windows. The right will show the “Unallocated” part. If you right click on the Active section, you’ll see that the “Extend Volume” option is greyed out, so it’s best just to delete it.

There’s no recovery of data from this. Anything on the stick will be gone forever, so do think again to make sure there’s nothing important on it.

And there you have it, the full capacity of the drive restored.

And having issued that warning, I should add that there’s no guarantee that the data isn’t recoverable. Just don’t rely on it. But, importantly, don’t rely on deleting a partition as a certain way of completely eliminating data that you want destroyed. There are likely tools available to recover it.

So, with all that in mind, select “Delete Partition” and click through the warning message. You’ll be rewarded with the whole 59.62GB now in one “Unallocated” block.

Right click on it and choose “New Simple Volume”. That starts up a wizard that steps you through the process. However you’ll have a choice only of exFAT or NTFS for formats, not FAT32. If your drive came formatted as FAT32, and that’s the way your applications need it, you’ll have to look to a third party tool to do the formatting. Windows won’t do it for you. Otherwise, exFAT is probably best. Even though not everything will read it, most modern devices will.