How do I compare folders

Hi Raymond,

I'm Dyari. Thanks for reaching out. I will be happy to assist you in this regard.

The easiest way is to compare them manually by doing right click on the folders separately > Properties > Compare "Size , Size on Disk and Contains" on both folders. This only compares files and folders number.

However, if you want to compare the whole folders contents, you should use third-party tool like Winmerge or Free Commander.

Please let me know if you need further assistance and keep me updated.

The easy way to do this with 100% certainty is to calculate a hash value for the original set of folders, and a second hash value for the copied folders. Then compare the two hash values. If as little as 1 byte of data in the copy is different, the hash values won't match.

I use the MD5 and SHA Checksum Utility app for this. The technical name for this type of software is a checksum utility.

Comparing the space occupied on the disk doesn't tell you whether the contents of that space is the same. And it's misleading because the same files could occupy different amounts of space on two different disks, depending on how the data is laid out.

Back in the day, comparing hashes is something you would do whenever you transferred a large amount of data from one volume to another volume. However, today disk I/O has become very reliable. Today, people compare hashes mostly when they're downloading large files from the internet, and the hash is used to ensure that the file that you wanted to download and the file that you actually downloaded are the same. Microsoft used to publish the hashes for Windows ISOs, but they no longer do.

Thanks Dyari for your quick reply. I've tried as you say to compare using properties. I'm copy from old external hdd to a new external hdd.

After comparing, i see the new external hdd shows example size is 3.71GB and size on disk is 3.76GB. Old hdd shows the same for both size and size on disk. Why is that so? It's the same number of files and size as I'm just copying.

'X' number of folders and files will occupy the same amount of space on two otherwise empty disks. But once those disks have data, Windows has to work around the space occupied by the existing data, so 'X' number of folders and files may require more or less space on the disk.

Hi Raymond,

You can compare them with TreeSize tool which is safe and free tool, it also indicate which file and folder is taking space.

https://www.jam-software.com/treesize_free

Open the tool with administrator > Click Select Directory > Choose your disk.

Do the same for external hard disk. You can open the tool for both simultaneously.

Then compare and find the differences.

Please let me know if you need further assistance,

Stay safe

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