How long do external hard drives last?

Most external hard drives last longer than the 3 to 5 years usually quoted. But some fail in their first weeks, and no figure tells you which kind you own. The longest public record comes from Backblaze, a cloud storage company. About 90% of its drives lasted four years and 65% lasted past six. It puts the median at about 6 years and 9 months. A study of 3,453 failed external drives by Secure Data Recovery, a recovery lab, found a median of 4,559 power-on hours. That is about 190 days of spinning, not six months of owning the drive. Keep a second copy of everything on the drive from day one.

What "how long a drive lasts" actually measures

An external hard drive is a spinning hard disk in a case with a USB cable. Your files sit on magnetic disks called platters. A motor spins them, and read and write heads on an arm float just above them. Those moving parts are why a hard drive wears out, and why a drop can kill it.

A drive's life can be counted on two clocks. One is calendar time: the years since you bought it. The other is running time, counted in power-on hours. That is how many hours the drive has been switched on. The drive keeps this count itself, in a built in health record called SMART, as attribute 9.

The two clocks can be far apart. A drive used an hour a week adds 52 hours a year. A drive that spins day and night adds 8,760. Mixing them up causes most of the confusion.

The median is the middle value: half the drives fail before it and half after. The annualized failure rate, or AFR, is the share of drives that fail over a year of running. An AFR of 1.41% means about 1.4 drives in every 100 fail per year.

Every figure in one table

Each source counts something different. Here they are side by side.

Only Backblaze follows a whole group of drives over time, so only Backblaze can say what share survive. But its drives are not external drives.

Why "six months" is the wrong reading

Secure Data Recovery's study is the newest source, and its headline numbers are easy to misread. Its key takeaways say the median external drive "failed at 190 days". They say 49.6% "did not reach the six-month mark". Read quickly, that sounds like half of all external drives die within six months of purchase.

That is not what was measured. The lab read each drive's power-on hours at the moment it failed. Its own table counts "Year 1" as 0 to 8,759 hours, a full year of spinning without a break. So the 190 days are days of running. The same goes for the average of 15,961 hours, which the lab turns into 665 days.

The bigger issue is who was counted. Every drive had already failed and been sent in for recovery between January 2023 and June 2026. A lab that only sees broken drives cannot tell you what share of drives break. The study says its sample "will likely include more early failures than the broader population".

What the study does show well is how external drives die. The lab names drops, power surges, extreme heat and factory defects as the leading causes. 2.2% of its drives failed in under 24 hours. And 27.2% failed with a pending sector count of zero. A pending sector is a spot on the disk the drive could not read reliably. A count of zero means SMART gave no warning.

One drive, three ways

Take a portable drive used for backups, and walk it through the study's median under three habits. Suppose it is plugged in for two hours once a week. That comes to 104 power-on hours a year. Reaching 4,559 hours at that pace would take about 44 years.

Now suppose it sits on a desk, attached to a computer that runs 8 hours every working day. That is about 2,080 hours a year. The drive would reach 4,559 hours in a little over 2 years.

Last, suppose it spins day and night. At 8,760 hours a year, it gets there in 190 days. Only in this case do "six months" and "190 days" mean the same thing.

None of this predicts when that drive will fail. It shows why one figure can mean six months or four decades.

What the 3 to 5 year rule gets right

Secure Data Recovery notes that articles giving 3 to 5 years tend to cite warranty lengths, and lighter use than a desktop drive gets. Neither is a count of drives. Backblaze explains drive failure with three causes: factory defects early on, random failures at any age, and parts that wear out after much use. Its fleet showed far fewer early failures than that theory predicts. Its failure rate stayed below 2% for the first three and a half years, then rose quickly through year six. Backblaze stopped measuring at six years, where its data thinned out. It extended the trend to estimate the median of 6 years and 9 months. It says it lacks the data to be certain, but knows the median is past six years for every model it uses.

So 3 to 5 years marks about where wear starts to show. It is not when most drives die. Newer figures agree: in Q2 2026, Backblaze counted an AFR of 1.73% for the quarter and 1.41% over the lifetime of 354,415 drives.

The catch is the setting. Backblaze's 2021 study covered over 200,000 standard 3.5 inch drives, mounted in storage servers. Secure Data Recovery points out that no fleet of external drives is big enough to track failure rates this way. An external drive faces everything a server drive does, plus the drops and surges the lab sees most.

The warranty is a different promise. WD's product pages list a 3 year limited warranty for My Passport and My Book. Seagate's support page lists 2 years for most One Touch HDD models, and its warranty checker gives the term for your serial number. WD's warranty starts on the purchase date on your receipt. It makes you responsible for "the loss, corruption, deletion or alteration of data howsoever caused". It does not pay for data recovery either. A warranty replaces the box, not what was in it.

What this answer does not cover

This page is about spinning hard drives. A portable SSD has a different weak point, covered in how long an SSD keeps data without power. None of the sources here measures how long a hard drive keeps data unpowered on a shelf, so no figure is given. Nothing here rates one model either. A healthy drive also says nothing about deleted files or ransomware that encrypts a connected drive. And if a drive has been dropped or starts to fail, these averages no longer apply to it. Copy off what you need before running anything that writes to it.

What to do with your external drive

Never keep the only copy on it. Every source above agrees that some drives fail early and without warning. The fix is the 3-2-1 backup rule: three copies, on two kinds of storage, one kept elsewhere. For family photos, a photo backup system that survives a lost phone makes the drive one copy among several. A cloud copy counts too, but check how long deleted files stay recoverable in the cloud first.

Handle it like a machine with moving parts. The lab suggests keeping the drive in a well ventilated spot, away from the edge of the desk. Pad it when you travel. Plug the computer into an uninterruptible power supply, a battery box that protects against power surges.

Do not wait for a warning. A SMART tool shows power-on hours, but more than a quarter of the lab's failed drives gave no warning there.

Plan for year four. Treat a drive past four years as one to double up or replace. On a laptop with little built in storage, the external drive often holds the only copy of older files. The trade off in whether 256 GB is enough for a laptop assumes that drive is backed up too.

The same moving parts sit inside an older computer that still runs on a spinning disk. If that machine feels slow, swapping the disk for an SSD is the biggest fix in why your computer is slow.