How Long Do Flash Drives Last?

Category: Gadgets , Hard-Drives

Flash drives are an increasingly popular form of portable storage. Some people predict that flash drives will replace hard drives in time, just as optical disks replaced floppy disks. But are flash drives as safe as other mass storage media for long-term archiving of irreplaceable data? Do flash drives ever wear out and have to be replaced? Are all flash drives created equal -- except for their capacities -- or are there differences in quality and durability to consider?

flash drive lifetime

Will You Outlive Your Flash Drive?

A flash drive contains a circuit board populated with transistors; usually one transistor per bit of storage capacity, although newer (and more expensive) transistors can store multiple bits. To store data on a flash drive, an electrical current changes the charge of a transistor from one state to another, representing either a zero or one, on or off bit. The design of the transistor is such that it remains in a given electrical charge state for many years. So your data stored on a flash drive won't fade away in any time frame that you're likely to worry about.

Flash drives are not as easily damaged as magnetic or optical media. There are no delicate moving parts in a flash drive such as read/write heads, spindle bearings, or disks of magnetic or optical media spinning at thousands of RPMs to collide, strike dust particles, etc. Yes, a cheaply made keychain USB flash drive's case may break if dropped or otherwise abused, and that may be the end of the flash drive's usefulness. But a digital camera's memory card is a flash drive, too, and it is so well armored and sealed you can drive a car over it or drop it in water and it will still work.

Can You Wear Out a Flash Drive?

If you just write data to a flash drive, unplug it from the computer and put it in a drawer, its memory will probably last longer than yours. The age of a flash drive isn't what's important. It turns out the crucial factor in flash drive longevity is how many times data is written to a particular storage block.

There is a limit to the number of times a flash drive's transistors can be switched from one electrical state to another; eventually, it will become impossible to write data to an exhausted transistor. In one hands-on test, this limit was found to be over 90 million write operations! Interestingly, the data already on the tested flash drive could still be read even when writing new data to it was no longer possible. Data was not lost.

I wouldn't consider that the final answer to the question of how long a flash drive will last. I've seen other people quoting an upper limit of 1 million write cycles per block, and cautioning that data loss could happen after 10 years of storage. Given that they're a pretty cheap form of storage, I'd personally err on the side of caution and move my data to a newer device every few years.

Flash Drive Quality

Flash drives can be purchased at dirt-cheap prices online. But you should take care that you get what you pay for. Look for a drive with a warranty of at least one year, as this is some indication of how much faith the manufacturer has in their own product. Some popular and well-respected brands are Sandisk, Kingston and Lexar.

Defective flash drives discarded by manufacturers are often scavenged and sold cheaply. Such a drive may be labeled as a 64 GB capacity, and your computer may even identify it as that size. But in fact, all but a handful of the bytes on the defective flash drive may be unusable. Fortunately, there is a free, easy way to determine the true capacity of any flash drive.

H2testw is a free, tiny utility that writes test data to a directory on your flash drive, reads it back, and verifies that what was written is what is read back. It's safe to use H2testw on a flash drive that already has data on it; no existing data will be overwritten or altered. But those untouched parts of the flash drive may contain defective transistors, so it's a good idea to run H2testw on an empty drive, after quick-formatting the drive. The site is in German but the "download" buttons are in plain English. Just click the first one, then the one on the next page, and your download should start. You can select English or German during the program's startup.

Do you have something to say about flash drives? Post your comment or question below...

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Most recent comments on "How Long Do Flash Drives Last?"

(See all 31 comments for this article.)

Posted by:

Lori A
12 Feb 2010

I've owned multiple flash drives and have had two name brand flash drives crash and I've lost hours of work (weeks in one case).

In both cases, each flash drive had over a year warranty -- one was a lifetime warranty although it was a first generation, but I didn't trust it a second time.

I don't abuse my flash drives, but both of them have quit without any warning. One quit in the middle of a save and the other quit when I tried to open a file.

Posted by:

12 Feb 2010

Is there a way to recover the photos on a memory card accidentally "erased"? On a Mac?

Posted by:

Stanley Reynolds
12 Feb 2010

My flash drives rarely last more than 6 months.
I use them several times a day. The most common failure is data corruption. The next most common failure is that the drive is no longer recognized by the computer.

I have tried many brands. My advice is to never use a flash drive to store data more than temporarily. Needless to say, I store data on at least 2 of them if I care about it.

Posted by:

12 Feb 2010

Does frequent unplugging of USB flashdrives without using the "Safely Remove.." windows feature shorten its life ?

Posted by:

12 Feb 2010

I have 2 2GB flash drives that have suddenly decided they are write protected. There are no external switches on them and they have only been removed using the safely remove button on XP. Any suggestions? The manufacturers have been no help at all.

Posted by:

12 Feb 2010

I also had associates and clients complain that their DOK's died on them after a short while. Sometimes I could pin it down to their having placed the DOK with their loose change. Now Nickels are made of nickel, a magnetic material. Soemtimes they've become magnetized or the carrier walked by a motor or transformer and made it history.

But sometimes, it has no obvious reason. I suspect it is a faulty USB port that zapped the DOK. This obvious when you hear a zzzzt sound or even see a spark when the DOK is plugged in. Why that occurs and which motherboards do it more often is another issue.

Posted by:

Ihor Prociuk
12 Feb 2010

One of the most important parts of a flash drive is the File Allocation Table (FAT). This is a predefined area of storage that keeps track of where files are located on the drive. It is accessed every time your read from or write to the drive so it gets the most use. If the FAT becomes corrupted, you won't be able to access the data even though it's still there. See the Wikipedia article on flash drives for more information.

There are some flash drive recovery utilities that will recover/retrieve your data. Some utilities are pretty basic: they (mostly) recover the data but not the file name. So you end up with a bunch of files with names like file001.dat file002.dat, etc. Others will recover the file name and file type. I've used with good success (disclaimer: I have no affiliation with the company and found them by searching the web). Their software is not free.

The best protection--BACK UP YOUR FLASH DRIVE REGULARLY (at least once a week or more frequently if you make heavy use of it). Today's computers have plenty of disk space. Simply copy the entire flash drive to your main hard drive.

Posted by:

Glenn P.
14 Feb 2010

"Back up your flash drives regularly"? And exactly what, pray, do you do when the flash drive IS your backup...???

EDITOR'S NOTE: Three word answer: Backup your backup.

Posted by:

Butch Grey
14 Feb 2010

I've been using Imation 512MB flash drives to backup-store financial records since 2006, on one have only used 48.6MB so far and it works flawlessly.

I also have Imation 2GB drive which stores some downloaded program files - no prob's there either.

(My PC is a Gateway with three USB ports on the

Posted by:

09 Jun 2010

Lexar's flash drives are a joke. Bought a 4 gig one yesterday..moved files onto kept shutting off while plugged in and I have just lost a file.(get the "cannot read file..corrupt.unreadable message)

I am NOT happy with Lexar at the moment.

Posted by:

20 Jun 2010

I have used a Lexar for several years now. It is not used every day and not used for backup. I don't trust flash drives yet for my "True" backups. I just recently bought a 4gig Lexar because of my experiences and my sister's experiences with them.

Posted by:

Stephanie Smith
06 Aug 2010

My 8 gb flash drive just quit working on me. I have pictures, music and documents on there and have never rewritten anything on it, but just all of a sudden, it stopped working. I went to plug it in and nothing came up. Tried plugging it into another computer and still nothing. Does this mean that it is no longer any good, or is there some other way to get my information off of this flash drive??

EDITOR'S NOTE: It's hard to tell if the problem is with the storage medium, or the USB connector. If wiggling the connector and re-inserting it doesn't fix it, then you'll have to consider a data recovery service.

Posted by:

Bent Ears Audio Laboratories
11 Mar 2011

Thank you for a very informative little article. I was fascinated to know the "hows" and "whys" concerning the life span of these amazing little devices. As to the durability of the drives, I can only say that my daughter has a SANDISK Cruiser flash which has, over time, taken no less than THREE trips through the laundry machine (a front-load unit with a 1200RPM final spin cycle!) and the drier - and still held the data stored on it! One day, when the prices drop to a level similar to that of standard internal disk drives, I'll be replacing my C drive with a solid-state flash unit. Right now, they are a bit too steep for my budget. I found mention of a 1000GB internal flash unit for $3800.

Anyway, thanks again for your great words.

Posted by:

12 Nov 2011

Tried to get the H2testw to download and work; however, I can't get it to do anything. Is this not functional for Windows 7 (64)? Sounds like a great program if I can make it work.

Posted by:

15 May 2012

I have some very nice old family photos I am scanning and want to back up. I already had one CD fail! I couldn't believe it -- none of the data was readable. But the originals on the hard disk are still there, so I'll try again. Is a memory stick safer, and longer lasting? Thanks

Posted by:

29 Jun 2012

Thanks for the article on Flash drives. However, I was looking for the answer to a related question. In thumbing through my Car Users Manual it cautions about leaving the USB Flash Drive plugged in when Starting the car and even when shutting it off. They indicate that because of the delicate nature of a Flash drive it can draw too much current and be destroyed. Is there a real danger of "Frying" the Flash Drive or is that possibility really very remote? Thanks for your comments.

EDITOR'S NOTE: If it were me, I'd err on the side of caution.

Posted by:

Future Savings
27 Dec 2013

I heard somewhere that within 10 years from now all storage devices will be done away with and everything will be paid storage on line.

Posted by:

james braselton
04 Aug 2014

hi.there I have comatose 64 with 64 kb storage still runs on flash today

Posted by:

22 Jun 2015

Okay, so if a flash drive's longevity is how many times data is written to a particular storage block, then is there a utility that can count the number of times data is written, subtracted by the planned life -- thus giving an estimate of remaining useful life of the flash drive?

Posted by:

05 Mar 2018

In reply to Kathy, the college teacher who says her students quite often say they lost their work due to their flash drives suddenly dying. It may be that "My flash drive died" is the new "My dog ate my homework".

There's more reader feedback... See all 31 comments for this article.

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