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How many passes does Defrag.exe take in Windows 10?

New laptop, and I started a while ago and it's now up to Pass 14

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  • I have seen some systems do 15 passes before completion. Depends on how bad the fragmentation is. Consolidating free space seems to take the most time. Your 24 passes is a record breaker!
    – Moab
    Aug 29, 2015 at 16:35

3 Answers 3

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Disk Defragmenter might take from several minutes to a few hours to finish, depending on the size and degree of fragmentation of your hard disk. You can still use your computer during the defragmentation process.

Microsoft never specifically says, because Windows auto-detects the needed settings. The amount and time is different for every situation.

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    Blimey, I'm used to the old 2 or 3 passes, not this new stuff. Thanks for the info.
    – SteveC
    Aug 29, 2015 at 15:44
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    No problem. I should probably point out that Windows 10 manages files in a way that greatly reduces the need for defragmentation.
    – Ulincsys
    Aug 29, 2015 at 15:49
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    And in the end, it did 24 passes !!
    – SteveC
    Aug 29, 2015 at 16:11
  • "few hours" my foot ... here I'm at step 4 and time spent so far "only" 30 hours, but I needed it, surface test of the hdd and overall speed test GOOD but transfer speed both write and read was becoming really poor (3-5M/s down from the initially over 100M/s) so, defrag was the only idea I was thinking it may be the problem and first analyse was 75% fragmented (which I google and seems to be ... CRITICAL) and disk is (a laptop - 2.5") 1T with 50G free so I guess it may be right but still ... "few hours" my foot :P Feb 11, 2016 at 14:30
  • @TheSourcerer You should clean up at least 100 gigs free - ideally 200 gigs - Windows takes a performance hit when your filesystem is > 80% full, which gets exponentially worse as it approaches 100%
    – davidgo
    Feb 17, 2016 at 7:02
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Windows 8 and up auto-detects the number of passes required depending on the SMART status, number of errors, size of disk, time since last inspection, etc. You can keep it running in background and does not affect your performance much on a decently speced device. It can take anywhere from 1-2 passes to 40 passes and more to complete. There is no set amount of defrag. You can also manually set the passes required if you use third party tools. Ho much fragmented was your drive?

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  • Can't remember the exact numbers, but it was a fresh installation on a new drive, so I'd assume not very fragmented
    – SteveC
    Oct 25, 2015 at 19:38
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Took me about 14 hours, at least 4 passes (each subsequent pass was significantly faster, might've been more than 4 passes but if so I missed seeing any passes above the 4th).

(1TB HDD, Windows 10, i5-8250U, laptop about 4 years old)

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