How can I compare big files under Windows? [closed]

I'd like to compare two files under Windows, each about 1Gb in size. I tried Total Commander and WinMerge, but both ended with Out of memory errors.

I'm running Vista Home Premium 64bit with 8GB of RAM so memory should not be an issue.

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11 Answers

What about just using fc or comp?

Both are included in Windows and should have no problems handling large files. In fact, 1 GiB is actually a pretty small file.

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My (ASCII) files were each about 1.2 GB.

I tried:

• NotePad++
• MultiEdit
• Beyond Compare 3
• ExamDiff Pro
• DiffMerge
• WinMerge and they all failed (couldn't load the file or crashed)

The one that worked for me at the end was ... PilotEdit x64 6.2.0.

It took some time to load each file and even more to do the comparison, but once it was done, it worked perfectly fine and just the way I had seen it in MultiEdit and NotePad++ before. Jumped between diff blocks, etc.

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If you want to find the differences rather than simply find out if the files are the same (via a checksum) then you could split the files first and then try a file comparison.
7-Zip File Manager will split files into 650Mb chunks (File > Split file...) which should then open in DiffMerge

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I use HashTab, worked fine for 1 GB files the last time I needed them and it's free.

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I use Beyond Compare for this. It is a very good tool for file comparison and directory synchronization (although it is not free :-(

2

Try ExamDiff (Pro).

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KDiff3 now has a 64 bit version which works for large files.

This is an old question, but I had the same problem when attempting to use KDiff3.

I was looking for a free option that wasn't a trial or only for non-commercial use. I discovered that I was using the 32 bit version of KDiff3 and it now has a 64 bit version. Installing it allowed me to diff much larger files.

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You could try a command line diff tool or DiffUtils for Windows. Textpad also has a comparison tool integrated it the files are text.

If you just need to detmine if the files are different (not what the differences are) use a checksum comparison tool that uses MD5 or SHA1. I use digestIT 2004.

I use Hex Workshop for comparing large files at hex level. Sure, it's not free, but it's worth every penny. There's plenty of hex editors, hex calculators, file comparison, etc. but this is one of those cases where the whole is much more than the sum of its parts

It looks like they are both 32-bit apps, so even on a 64-bit platform they are bound to a 2GB max memory usage limit. Though, you would think they would have another way of handling this, such as paging the extra data.

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I use ExamDiff but I am not sure if it will work for ~1GB files.